Background

In 2007, genome-wide association studies (GWAS) using SNP arrays resulted in the near simultaneous reporting of the first common genetic variant that affects the risk of coronary heart disease (CHD; defined as inadequate circulation to cardiac muscle and surrounding tissue resulting in MI, unstable angina pectoris, coronary revascularization, or death) in Caucasians.(1-4) The SNPs commonly reported across these studies were supplemented with more SNPs with similar estimates of CHD risk in the same and additional studies. These SNPs were confirmed in case control replication studies in a variety of study populations, showing that the identified SNPs were associated with CHD and even more specifically with MI.(5) All of the SNPs were found within a locus spanning a 58-kilobase region at chromosome 9p21.3 (thus the locus is sometimes represented more specifically as 9p21.3; for simplicity, 9p21 will be used for the rest of this document), are highly correlated (r²>0.8) and thus are said to be in linkage disequilibrium (nonrandom association of alleles). In all studies, the association of any identified SNP with CHD risk was shown to be independent of traditional risk factors.(5)

Several studies have extended the 9p21 association to other vascular diseases including ischemic stroke; thus 9p21 may be reported as associated with CVD outcomes, defined as including CHD outcomes plus ischemic stroke. Associations have also been reported with AAA and with intracranial arterial aneurysm.(6)

Several genes are found at the 9p21 locus, including ANRIL, which encodes a large noncoding RNA that may have regulatory functions, and CDKN2A and CDKN2B, which encode cyclin-dependent kinase inhibitors.(6) The mechanisms by which the SNPs lead to increased CHD risk have been largely unknown. Recently, Harismendy et al identified several potential enhancer regulatory DNA sequences in the 9p21 region.(7) They reported that the SNP rs10747278, consistently associated with increased risk of CHD, occurs in one of these enhancer sequences and that the risk allele disrupts a transcription factor binding site involved in the inflammatory response (STAT1). The interaction of STAT1 with part of the inflammatory signaling pathway, interferon-gamma, is impaired in 9p21 risk carriers. Congrains et al genotyped 18 SNPs across the CVD-associated region and encompassing ANRIL and CDKN2A/B to determine the impact of 9p21 variants on gene expression. (8) The authors reported that “several SNPs in 9p21 locus affect the expression of ANRIL, which is further in control of the regulation of CDKN2A/B and cell growth. Cell proliferation mediates the progression of atherosclerosis and is also directly or indirectly involved in the pathogenesis of diseases associated with this locus.”

Commercially Available Tests Several laboratories offer 9p21 genotyping. For example, the Berkeley HeartLab (Quest Diagnostics) offers the 9p21 Genotype Test, which detects the rs10757278 A>G and rs1333049 G>C SNPs within the 9p21 locus of chromosome.(9) Baylor Miraca Genetics Laboratories offers genotyping of the rs10757278 A>G polymorphism at 9p21.

Cardiac risk genotyping panels offered by other laboratories may include and individually report 9p21 SNP results. For example, the deCODE MI™ (deCODE Genetics, Reykjavik) test genotypes 9p21.3 rs10757278 in addition to 7 other SNPs from other chromosomal loci to estimate the risk of CHD and MI.

Regulatory Status

There is no manufactured test kit for 9p21 genotyping that has been reviewed by the U.S. Food and Drug Administration. 9p21 genotyping tests are laboratory-developed tests, offered by clinical laboratories licensed under Clinical Laboratory Improvement Amendment for high-complexity testing.

Related Policies

• Measurement of Lipoprotein-Associated Phospholipase A2 (Lp-PLA2) in the Assessment of Cardiovascular Risk (Policy #014 in the Pathology Section)
• Novel Lipid Risk Factors in Risk Assessment and Management of Cardiovascular Disease (Policy #032 in the Pathology Section)

For Medicare Advantage, Medicaid and FIDE-SNP, please refer to the Coverage Sections below for coverage guidance.)

The use of genotyping for 9p21 single nucleotide polymorphisms (SNPs) is considered investigational for all clinical uses, including but not limited to identification of patients who may be at increased risk of cardiovascular disease or its manifestations (eg, myocardial infarction, , ischemic stroke, peripheral arterial disease, coronary artery calcification), or identification of patients who may be at increased risk for aneurysmal disease (aortic abdominal aneurysms, intracranial aneurysms, polypoidal choroidal vasculopathy).


Medicare Coverage:
There is no National Coverage Determination (NCD) for Genotyping for 9p21 Single Nucleotide Polymorphisms to Predict Risk of Cardiovascular Disease or Aneurysm. In the absence of an NCD, coverage decisions are left to the discretion of Local Medicare Carriers. Novitas Solutions, Inc, the Local Medicare Carrier for jurisdiction JL, has not issued a determination for this service. Therefore, Medicare Advantage Products will follow the Horizon BCBSNJ Medical Policy.

Medicaid Coverage:
For members enrolled in Medicaid and NJ FamilyCare plans, Horizon BCBSNJ applies the above medical policy.

FIDE SNP:

For members enrolled in a Fully Integrated Dual Eligible Special Needs Plan (FIDE-SNP): (1) to the extent the service is covered under the Medicare portion of the member’s benefit package, the above Medicare Coverage statement applies; and (2) to the extent the service is not covered under the Medicare portion of the member’s benefit package, the above Medicaid Coverage statement applies.

[RATIONALE:
This policy was created in 2011 and updated periodically with literature review. The most recent literature update was performed through January 2019.

Analytic Validity

In the case of 9p21 mutations, analytic validity refers to a test’s technical accuracy in detecting a mutation that is present or in excluding a mutation that is absent. Limited information is available on the analytic validity of the available 9p21 genotyping methods. The deCODE MI test is based on the Centaurus™ Assay (Nanogen Inc., San Diego, CA), which is a real-time polymerase chain reaction (PCR)‒based assay that uses fluorescence detection of PCR products by spectrometry.(3) Published literature describing the development of the Centaurus Assay reported 100% concordance with a criterion standard.(9) Real-time PCR-based methods are generally considered to have high accuracy.

Clinical Validity

9p21 polymorphisms have been associated with multiple types of cardiovascular disease (CVD). The strength of association between the polymorphisms and each disease type (ie, clinical validity) is discussed separately.

9p21 Polymorphisms and Coronary Heart Disease

Meta-analyses. Palomaki et al conducted the first formal systematic review of the 9p21 literature to estimate the strength of the association between established 9p21 single nucleotide polymorphism (SNP) variants and coronary heart disease (CHD) and to examine clinical utility.(10) This review was commissioned by the Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group (EWG). Sixteen published studies that analyzed 47 data sets and that reported 9p21 SNP genotypes in association with outcomes of CHD (including myocardial infarction [MI]) or coronary artery disease (CAD; the result of the accumulation of atheromatous plaques within the walls of the coronary arteries that supply the myocardium, and the most common cause of CHD) were included in this review. Ischemic stroke and aneurysm outcomes were excluded from this analysis; all CHD/CAD outcomes were combined. Data sets were limited to Asian and white populations.

Three publications were cohort studies, the rest case control studies (level 1 and level 2 evidence, respectively, using EWG methods).(11) Five SNPs in the 9p21 locus (rs1333049, rs10757274, rs2383207, rs2891168, and rs10757278) covered all studies/data sets. First, the review demonstrated that the choice of SNP was relatively unimportant; in combining the data from 2 studies, 4 SNPs provided nearly identical odds ratios (ORs). Thus, the results from only 1 SNP per study were used.

Across all studies, consensus genotype frequencies in controls were 27%, 50%, and 23% for 0, 1, and 2 at-risk alleles, respectively. The random-effects summary OR across all studies/data sets was 1.25 (95% confidence interval [CI], 1.21 to 1.29; p<0.001; I²=10%) for subjects with 2 at-risk SNP alleles compared with subjects with 1 at-risk allele. When the same analysis was restricted to individuals younger than 55 years of age, the summary OR increased to 1.35 (95% CI, 1.3 to 1.4). Limiting the data sets to only those with upper age cutoff levels greater than 70 years, the summary OR was 1.19 (95% CI, 1.13 to 1.25; p<0.001). For subjects (all data sets) with no at-risk alleles compared with subjects with 1 at-risk allele, the summary OR was 0.80 (95% CI, 0.77 to 0.82; p<0.001). No differences were found between Asians and whites.

Since this study, several additional meta-analyses of 9p21 genotyping have been published. Schunkert et al and the CARDIOGRAM Consortium conducted a meta-analysis of 14 genome-wide association studies of CAD.(12) The 9p21 association per risk allele with CAD, as measured by SNP rs4977574, was 1.29 (95% CI, 1.23 to 1.36; p=1.35´10⁻²²). In an earlier report of this analysis, the association was stronger among cases younger than 50 years of age at an OR of 1.45 (p<0.001).(13) The Coronary Artery Disease Genetics Consortium meta-analyzed 4 large GWASs of CAD and reported an allele risk of 1.20 (95% CI, 1.16 to 1.25; p=1.62´10⁻²⁵) for 9p21 SNP rs4977574 and CAD.(14) These results compare well with Palomaki et al.(10)

Zhou et al conducted a meta-analysis of 7 case control studies (N=7123 total) and found associations between early-onset CAD and rs2383207 (OR=0.79; 95% CI, 0.71 to 0.88; p<0.001), rs10757278 (OR=1.28; 95% CI, 1.15 to 1.42; p<0.001), rs10757274 (OR=1.17; 95% CI, 1.08 to 1.33; p=0.02), and rs2383206 (OR=1.17; 95% CI, 1.10 to 1.25; p<0.001).(15) In a meta-analysis of 21 studies that included patients with information on CAD, MI status and 9p21 genotype (N=33,673), Chan et al also found associations with CAD and the 9p21 locus and reported an OR of 1.15 (95% CI, 1.04 to 1.26) for heterozygous carriers and an OR of 1.23 (95% CI, 1.08 to 1.39) for homozygous carriers. However, when underlying CAD was present in both case subjects (n=17,791) and control subjects (n=15,882), the prevalence of MI was not significantly associated with the 9p21 risk allele (OR=0.99; 95% CI, 0.95 to 1.03).(16) In a meta-analysis of 21 case control studies evaluating the association between 9p21 SNPs and CHD in an east Asian population, including 25,945 cases and 31,777 controls, Dong et al found a significant association between the allele rs1333049 and CHD (OR=1.30; 95% CI, 1.25 to 1.35; p<0.001).(17)

Individual Studies: 9p21 polymorphisms and CHD/CAD. Several studies analyzing individual patient cohorts or case control populations for association of 9p21 and CHD/CAD have been published since the Palomaki et al review.(5,19-27) Most results again compare well with Palomaki et al. Scheffold et al(5) evaluated a population of male patients with acute MI compared with an otherwise comparable population of males without an event and reported a slightly higher allele risk for several 9p21 SNPs (approximate OR range, 1.6-1.9). The estimates increased when the population was limited to those cases with a family history of MI (approximate OR range, 1.9-2.8); the authors point out that the combination risk factor of family history plus 9p21 status is similar in value to those of traditional risk factors such as hypertension, diabetes mellitus, and current smoking.

Beckie et al studied the allelic frequencies and haplotype structure of genetic variants on chromosome 9p21 in a cohort of black and white women with early onset CHD.(24,25) The authors report interethnic diversity in the SNP risk alleles and the haplotype structure of chromosome 9p21 SNP variants, suggesting that different variants may influence CHD in whites and blacks. Shiffman also reported no association of rs10757274 and incident MI in African American men (n=228) and women (n=405) aged 65.2 or older.(27)

Wang et al studied CAD in a Chinese Han cohort with and without type 2 diabetes.(28) An adjusted (gender, hypertension, hyperlipidemia, smoking) analysis of the homozygous risk genotype for rs1333049 showed an increased risk of early-onset CAD among diabetic patients (OR=2.367; 95% CI, 1.258 to 4.453; p=0.008), but not among nondiabetic patients (OR=1.632; 95% CI, 0.995 to 2.654, p=0.057).

Individual Studies: 9p21 Allele Dosage and Disease Severity, Progression, and Risk of Death.
Dandona et al reported a strong direct association between the proportion of early onset patients with angiographically determined 3-vessel disease and increasing gene dosage of 9p21 SNP rs1333049 (per risk allele copy OR=1.45; 95% CI, 1.18 to 1.79; p=4.2610-4).(21) Patel et al also reported greater 9p21 risk allele frequency with increasing angiographically defined CAD severity (p=0.003).(22) In a case control study with a 10-year follow-up of cases (n=1508), Ardissino et al reported that rs1333040 was significantly associated with coronary atherosclerosis progression (heterozygous hazard ratio [HR], 1.5; 95% CI, 1.17 to 2.02; homozygous HR=2.2; 95% CI, 1.3 to 2.7).(29) There was no significant association with cardiovascular death or the recurrence of MI.

Szpacowicz et al evaluated the association of the 9p21 SNPs rs1333049, rs10757278, and rs4977574 with 5-year all-cause mortality in a cohort of 589 patients who underwent percutaneous coronary intervention for ST-elevation MI.(30) Results were published in 2014, after retraction of a previous publication due to reporting of an incorrect allele being associated with mortality. In the cohort as a whole, there was no significant association between genotype and mortality. Among the subgroup of 238 patients with high risk of death (GRACE risk score, ≥155), the heterozygotes or homozygotes with a high -risk genotype had higher risk of mortality (for rs10757278: HR=2.2; 95% CI, 1.15 to 4.2; for rs4977574: HR=2.7; 95% CI, 1.3 to 5.4; for rs1333049, HR=2.3; 95% CI, 1.2 to 4.5).

9p21 Polymorphisms and Ischemic Stroke

Meta-Analyses. Several studies have reported, with mixed results, on the association of 9p21 with ischemic stroke, an outcome not included in the studies discussed in the prior text. Anderson et al conducted a meta-analysis of 8 studies, focusing on 2 9p21 SNPs, s1537378 and rs10757278.(32) Inclusion of all data resulted in a high degree of heterogeneity; restriction to only those studies with sufficient information to allow stroke subtype-specific analysis (n=5) resulted in an overall OR estimate of 1.15 (95% CI, 1.08 to 1.23; p<0.001), and a large artery subtype estimate from 3 cohorts of 1.20 (95% CI, 1.08 to 1.33; p<0.001), suggesting that the risk is largely restricted to the large artery subtype.

In a meta-analysis by Traylor et al of 15 studies that included 12,389 subjects with ischemic stroke and 62,004 controls, the 9p21 locus was only associated with large-vessel stroke.(33)

Dichgans et al(34) analyzed data from the CARDIOGRAM/C4D consortium study previously described(12,13) in conjunction with data from the METASTROKE consortium(33) to evaluate whether CAD and ischemic stroke share genetic risk in respect to common genetic variants. The authors found that the 9p21 locus was significantly associated with both CAD and the phenotype of large artery stroke ( p for association with large artery stroke: 3.8510-6; p for the joint phenotype of CAD and large artery stroke: 2.9x10-35).Ni et al reported results of a meta-analysis of genetic association studies between 9p21 polymorphisms and ischemic stroke, which included 21 studies with 34,128 patients and 153,428 controls.(35) The rs10757278 polymorphism was significantly associated with increased overall ischemic stroke risk (per-allele OR for ischemic stroke: 1.11; 95% CI, 1.07 to 1.15; p<10-5) and increased large-vessel stroke risk (per-allele OR for large vessel stroke, 1.15; 95% CI, 1.10 to 1.19), but not with small vessel, cardioembolic, or other types of stroke.

Individual Studies. Since publication of the previous meta-analyses, a number of individual studies have evaluated the association between 9p21 polymorphisms and ischemic stroke. For example, in a retrospective study evaluating the association between macro- and microscopic infarcts on neuropathology, Chou et al reported that the 9p21 SNP at the CDKN2A/B locus (rs2383207) was significantly associated with the presence of macroscopic infarct on pathology (OR=1.26; 95% CI, 1.02 to 1.55; p=0.031).(36)

Other studies have focused on particular population subsets, with mixed findings. Olsson et al published a case control study of the association of 9p21 and ischemic stroke in individuals younger than 70 years.(37) In this study, the low-risk allele of 9p21 SNP rs7857345 showed significant association with decreased risk of large vessel disease after adjusting for traditional risk factors (OR=0.58; 95% CI, 0.39 to 0.86). However, not all tested 9p21 SNPs were significant. Dutta et al studied CAD mortality at older ages in association with 9p21 variants, reporting a positive association with mortality but no significant association with deaths due to stroke (HR=1.07; 95% CI, 0.81 to 1.41; p=0.63).26 Yue et al reported significant associations between the SNPs rs2383207, rs3731245, and rs1537378 were significantly associated with cerebral infarction in a Chinese Han population (OR=1.18, 95% CI, 1.01 to 1.37; OR=1.29; 95% CI, 1.06 to 1.56; OR=1.30; 95% CI, 1.05 to 1.60, respectively).(38)

9p21 Polymorphisms and Aneurysms

The 9p21 locus has been associated with risk of both intracranial and abdominal aortic aneurysms. In 2013, Alg et al reported results from a systematic review and meta-analysis of all genetic association studies of sporadic intracranial aneurysm to identify genetic risk factors for intracranial aneurysm.(39) The authors included 66 cohort or case control studies of intracranial aneurysms that examined a total of 41 SNPs, not limited to the 9p21 locus, in 29 genes. Among polymorphisms with the strongest associations with intracranial aneurysm were the 9p21 SNPs rs10757278 (OR=1.29; 95% CI, 1.21 to 1.38) and rs1333040 (OR=1.24; 95% CI, 1.20 to 1.29).

There has been a greater focus on the association of 9p21 with abdominal aortic aneurysm (AAA). Several studies report 9p21 allele-specific estimates of risk in the range of 1.2 to 1.8.(40-44) Biros et al combined the results of a cohort study including 3371 men, 513 with AAA, with the results of previous studies and reported a combined estimate of about 1.3 for both 9p21 SNPs rs10757278 and rs1333049.(43) This is lower than other well-characterized risk factor estimates for AAA such as age (OR=1.7 per 7 years), family history (OR=1.9), and smoking (OR=5).(45) Wei et al reported slightly higher risk of AAA associated with homozygosity for the rs10757278 and rs1333040 risk alleles in a Chinese Han population, after controlling for other AAA risk factors (OR=2.31; 95% CI, 1.22 to 4.36; OR=2.14; 95% CI, 1.13 to 4.05, respectively).(46)

Association of 9p21 with Other Conditions

A few studies have explored the association of 9p21 variants with a variety of other conditions such as peripheral arterial disease,(47) coronary artery calcification,(48) aortic calcification,(49) polypoidal choroidal vasculopathy (characterized by aneurismal dilations at the border of the choroidal vascular network),(50) arterial stiffness in hypertensive individuals,(51) and brain arteriovenous malformation.(52,53) In contrast, Folsom et al found no association between SNPs at the 9p21 locus with arterial elasticity and retinal microvascular diameter.(54)

While some studies reported positive associations, the strength of the associations was modest and none suggested clinical use.

Section Summary

The clinical validity of the association between 9p21 polymorphisms and CHD/CAD incidence and outcomes is well-established and consistent in multiple independent populations, with evidence of increasing severity of outcomes with increasing risk allele dosage. The magnitude of increased risk is modest, with ORs for CVD generally in the 1 to 2 range. The clinical validity for the association between 9p21 polymorphisms and ischemic stroke, , and other vascular disorders is less well-studied and less certain.

Clinical Utility

Clinical utility is demonstrated when the evidence shows that using a test changes medical management for at least some patients, and these changes lead to improved outcomes. Most of the evidence related to the clinical utility of 9p21 testing is related to its role in risk-stratifying patients for CHD; a smaller body of evidence exists for its utility in other conditions.

Clinical Utility of 9p21 Genotyping for CHD
Palomaki et al addressed clinical utility of 9p21 genotyping with a reclassification analysis, evaluating whether genotyping helped reclassify individuals more accurately than traditional risk factors according to their known outcomes, which was measured by calculating the net reclassification index (NRI) with data from 3 studies/4 data sets.(10) For the 4 data sets, the proportions of cases reclassified by 9p21 genotype after initial classification by traditional risk factors were 0.5%, 0.7%, 2.5%, and -0.1%; of controls, 0.3%, 4.2%, -0.1%, and 0%; corresponding NRIs were 0.8%, 4.9%, 2.5%, and -0.2%; none of the NRIs were statistically significant. In addition, the study showing the largest NRI achieved most of the risk reclassification because of reduced risk in subjects without events, which would have less chance of improving outcomes. Moreover, in 2 individual studies the NRI actually worsened when 9p21 risk alleles were added to algorithms that also included family history as a CAD risk factor.(55,56)

Dutta et al also conducted a reclassification analysis, evaluating risk first with Framingham score, then with 9p21 SNP-determined risk added to the Framingham score.(26) In their cohort of community-dwelling elderly subjects followed for 20 years after DNA collection (N=1095), SNP risk predictors identified an additional 6% (n=5) of the 81 CAD deaths within 10 years in the high-risk group, compared with the 21% (n=17) identified by Framingham score. However, an NRI was not reported for a full evaluation of the results. In a similar analysis, Shiffman et al found that adding a 9p21 SNP risk variant to the Framingham score did not improve the area under the curve (AUC) and that the net number of subjects who were reclassified to more appropriate risk categories was 25 or fewer out of 3651 whites, with a NRI of 0.02 or less (p≥0.4).(27) Adding C-reactive protein and KIF6 (see Policy No. 2.04.67) resulted in a larger number of correctly reclassified white men (n=93, p=0.04), but did not improve risk prediction for white women. Studies have also used the OR associated with a subject’s 9p21 genotype to modify a risk assessment based on traditional risk factors. For example, based on the results of Palomaki et al,(10) a subject with a 10-year CHD risk of 10% based on traditional risk factors who has two 9p21 at-risk alleles would have his risk estimate increased to about 14% (10%1.21.2) compared with a subject with no at-risk alleles. Davies et al,(23) however, found that the addition of 9p21 to traditional risk factors was not significant as measured by AUC (0.8013 with traditional risk factors alone vs 0.8044 with traditional risk factors plus 9p21; p=0.097). Other similar attempts to add 9p21 alone as a risk factor have not demonstrated significance in addition to traditional risk factors.(55-57) An improved risk calculation, if shown, would be an intermediate outcome. The expectation is that improved risk assessment might influence patient and provider decisions about preventive interventions and behavioral change. However, as Palomaki et al(10) note, only 37% of U.S. physicians reported regular use of a heart disease risk score,(58) and the evidence that such risk scores translate into net clinical benefits is minimal.(59) Thus, the clinical utility of 9p21 genotyping cannot be assumed even if risk assessment is improved.

Do et al(60) tested several 9p21 SNPs in 3820 cases and 4294 matched controls from the multiethnic INTERHEART study of risk factors for acute nonfatal MI, and also collected dietary information. As expected, the SNPs were significantly associated with MI with ORs of approximately 1.2. An analysis of interactions found no significant effect of physical activity or smoking, but a significant interaction with the prudent diet (ie, raw vegetables, fruits, green leafy vegetables, nuts, desserts, dairy products) score, the most significant interaction being with raw vegetable intake. A second, similar analysis in the prospective FINRISK study, a series of population-based CVD risk factor surveys conducted every 5 years in Finland, found a similar interaction with diet and additionally found that the effect was diminished in the high prudent diet consumption group. Thus, the risk effect of the SNP variants may be most pronounced when diet is poor. Although not yet direct evidence of clinical utility, the results suggest the modification of low-level genetic risk with diet.
Gransbo et al evaluated the incremental impact of a 9p21 SNP (rs497757) on CVD risk prediction.(61) The authors used data from the Malmo Diet and Cancer study, a prospective, population-based cohort study that included 28,449 subjects, with the primary outcome of incident CVD. NRI was calculated when the presence of the rs4977574 SNP was added to a prediction model that used traditional risk factors (age, sex, hypertension, lipid-lowering therapy, diabetes, smoking, body mass index). While there was a significant association between the rs4977574 SNP and incident CVD, the addition of the 9p21 genotype did little to improve risk prediction in additive multivariate models. Although statistically significant, the NRI was small (1.2%, p=0.043).

Gransbo et al evaluated the incremental impact of a 9p21 SNP (rs497757) on CVD risk prediction.(61) The authors used data from the Malmo Diet and Cancer study, a prospective, population-based cohort study that included 28,449 subjects, with the primary outcome of incident CVD. NRI was calculated when the presence of the rs4977574 SNP was added to a prediction model that used traditional risk factors (age, sex, hypertension, lipid-lowering therapy, diabetes, smoking, body mass index). While there was a significant association between the rs4977574 SNP and incident CVD, the addition of the 9p21 genotype did little to improve risk prediction in additive multivariate models. Although statistically significant, the NRI was small (1.2%, p=0.043).

Clinical Utility of 9p21 and Other CVD

Downing et al evaluated the impact of adding 9p21 polymorphism (rs10757269) in a risk-factor-based model predicting peripheral artery disease.(62) Among 393 subjects in the prospective Genetic Determinants of Peripheral Artery Disease study who met study inclusion criteria, the rs10757269 allele was associated with the presence of peripheral artery disease (defined as ankle–brachial index <0.9) after controlling for traditional cardiovascular risk factors and other biomarkers (OR=1.92; 95% CI, 1.29 to 2.85). The addition of 9p21 genotype to a previously-validated peripheral artery disease risk model (including age, sex, race, smoking history, body mass index, hypertension stage, diabetes status, history of CVD, heart failure, CAD) lead to improved risk classification (NRI=33.5%, p=0.001).

Section Summary

The clinical utility of 9p21 mutation testing has not been established. The contribution of 9p21 genotyping to overall cardiovascular risk assessment, above that of traditional risk factors, is small and not likely to be clinically important. Studies of risk reclassification do not report that 9p21 testing results in substantial numbers of patients being reclassified to clinically relevant categories. No studies were identified that evaluate whether the use of 9p21 genotyping is associated with changes in patient management, improvements in clinical outcomes, or both.

Ongoing and Unpublished Clinical Trials

Some currently unpublished trials that might influence this policy are listed in Table 1.

Table 1. Summary of Key Active Trials

NCT No.	Trial Name	Planned Enrollment	Completion Date
Unpublished
NCT01658137	Dietary Intervention Trial to Understand the Mechanism Underlying the 9p21 Variant Interaction With High Fruits and Vegetable Consumption	80	Jul 2013 Status is listed as Unknown
NCT01766271	GENErating Change, An Integrative Health Coaching and Genetic Risk Testing Pilot in Primary Care: A Multidisciplinary Approach to Personalized Medicine Targeting CHD Risk	31	Oct 2014 Status is listed as Completed; no results

NCT: national clinical trial.

Summary of Evidence
The association of single nucleotide polymorphisms at the 9p21 locus with coronary artery/heart disease (CAD/CHD) incidence and outcomes (clinical validity) is well-established and consistent in multiple independent populations, with evidence of increasing severity of outcomes with increasing risk allele dosage. The clinical validity for the association of 9p21 polymorphisms ischemic stroke, aneurysms, or other vascular disorders is less well-studied and less certain. Despite evidence that 9p21 polymorphisms are associated with CAD/CHD outcomes, the clinical utility of 9p21 genotyping has not been established. Studies have not conclusively demonstrated that 9p21 genotyping significantly improves risk reclassification after initial classification by traditional risk factors or that the addition of 9p21 genotyping to traditional risk factors improves risk assessment. No studies were identified that evaluate whether the use of 9p21 genotyping is associated with changes in patient management, improvements in clinical outcomes, or both. Thus, 9p21 genotyping for all applications is investigational.

SUPPLEMENTAL INFORMATION

Practice Guidelines and Position Statements

In 2013, the American College of Cardiology Foundation and the American Heart Association Task Force on Practice Guidelines issued guidelines on the assessment of cardiovascular risk, which did not address assessment of 9p21 polymorphisms.(63)

The Evaluation of Genomic Applications in Practice and Prevention Working Group (EWG) published a recommendation on “genomic profiling to assess cardiovascular risk to improve cardiovascular health,” which included a recommendation on 9p21 profiling alone based on Palomaki et al.10 In general, the EWG found “… insufficient evidence to recommend testing for the 9p21 genetic variant or 57 other variants in 28 genes ... to assess risk for cardiovascular disease (CVD) in the general population, specifically heart disease and stroke. The EWG found that the magnitude of net health benefit from use of any of these tests alone or in combination is negligible. The EWG discourages clinical use unless further evidence supports improved clinical outcomes. Based on the available evidence, the overall certainty of net health benefit is deemed “low.” (64)

U.S. Preventive Services Task Force Recommendations

No recommendations for 9p21 genotyping to identify risk for cardiovascular disease have been identified.]
________________________________________________________________________________________

Horizon BCBSNJ Medical Policy Development Process:

This Horizon BCBSNJ Medical Policy (the “Medical Policy”) has been developed by Horizon BCBSNJ’s Medical Policy Committee (the “Committee”) consistent with generally accepted standards of medical practice, and reflects Horizon BCBSNJ’s view of the subject health care services, supplies or procedures, and in what circumstances they are deemed to be medically necessary or experimental/ investigational in nature. This Medical Policy also considers whether and to what degree the subject health care services, supplies or procedures are clinically appropriate, in terms of type, frequency, extent, site and duration and if they are considered effective for the illnesses, injuries or diseases discussed. Where relevant, this Medical Policy considers whether the subject health care services, supplies or procedures are being requested primarily for the convenience of the covered person or the health care provider. It may also consider whether the services, supplies or procedures are more costly than an alternative service or sequence of services, supplies or procedures that are at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of the relevant illness, injury or disease. In reaching its conclusion regarding what it considers to be the generally accepted standards of medical practice, the Committee reviews and considers the following: all credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, physician and health care provider specialty society recommendations, the views of physicians and health care providers practicing in relevant clinical areas (including, but not limited to, the prevailing opinion within the appropriate specialty) and any other relevant factor as determined by applicable State and Federal laws and regulations.

___________________________________________________________________________________________________________________________

Index:
Genotyping for 9p21 Single Nucleotide Polymorphisms to Predict Risk of Cardiovascular Disease or Aneurysm
Genomic Profiling, Cardiovascular Disease Risk
EarlyMICheck Genotype Test
9p21- EarlyMICheck Genotype Test
deCODE MI

References:
1. Wellcome Trust Case Control Consortium: Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls. Nature 2007; 447(7145):661-78.

2. McPherson R, Pertsemlidis A, Kavaslar N et al. A common allele on chromosome 9 associated with coronary heart disease. Science 2007; 316(5830):1488-91.

3. Helgadottir A, Thorleifsson G, Manolescu A et al. A common variant on chromosome 9p21 affects the risk of myocardial infarction. Science 2007; 316(5830):1491-3.

4. Samani NJ, Erdmann J, Hall AS et al. Genomewide association analysis of coronary artery disease. N Engl J Med 2007; 357(5):443-53.

5. Scheffold T, Kullmann S, Huge A et al. Six sequence variants on chromosome 9p21.3 are associated with a positive family history of myocardial infarction: a multicenter registry. BMC Cardiovasc Disord 2011; 11:9.

6. Johansen CT, Lanktree MB, Hegele RA. Translating genomic analyses into improved management of coronary artery disease. Future Cardiol 2010; 6(4):507-21.

7. Harismendy O, Notani D, Song X et al. 9p21 DNA variants associated with coronary artery disease impair interferon-gamma signalling response. Nature 2011; 470(7333):264-8.

8. Congrains A, Kamide K, Oguro R et al. Genetic variants at the 9p21 locus contribute to atherosclerosis through modulation of ANRIL and CDKN2A/B. Atherosclerosis 2012; 220(2):449-55.

9. Kutyavin IV, Milesi D, Belousov Y et al. A novel endonuclease IV post-PCR genotyping system. Nucleic Acids Res 2006; 34(19):e128.

10. Palomaki GE, Melillo S, Bradley LA. Association between 9p21 genomic markers and heart disease: a meta-analysis. JAMA 2010; 303(7):648-56.

11. Teutsch SM, Bradley LA, Palomaki GE et al. The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Initiative: methods of the EGAPP Working Group. Genet Med 2009; 11(1):3-14.

12. Schunkert H, Konig IR, Kathiresan S et al. Large-scale association analysis identifies 13 new susceptibility loci for coronary artery disease. Nat Genet 2011; 43(4):333-8.

13. Preuss M, Konig IR, Thompson JR et al. Design of the Coronary ARtery DIsease Genome-Wide Replication And Meta-Analysis (CARDIoGRAM) Study: A Genome-wide association meta-analysis involving more than 22 000 cases and 60 000 controls. Circ Cardiovasc Genet 2010; 3(5):475-83.

14. A genome-wide association study in Europeans and South Asians identifies five new loci for coronary artery disease. Nat Genet 2011; 43(4):339-44.

15. Zhou LT, Qin L, Zheng DC et al. Meta-analysis of genetic association of chromosome 9p21 with early-onset coronary artery disease. Gene 2012; 510(2):185-8.

16. Chan K, Patel RS, Newcombe P et al. Association between the chromosome 9p21 locus and angiographic coronary artery disease burden: a collaborative meta-analysis. J Am Coll Cardiol 2013; 61(9):957-70.

17. Dong L, Wang H, Wang DW et al. Association of chromosome 9p21 genetic variants with risk of coronary heart disease in the East Asian population: a meta-analysis. Ann Hum Genet 2013; 77(3):183-90.

18. Lian J, Ba Y, Dai D, et al. A replication study and a meta-analysis of the association between the CDKN2A rs1333049 polymorphism and coronary heart disease. J Atheroscler Thromb. 2014;21(11):1109-1120. PMID 24930384

19. Paynter NP, Chasman DI, Pare G, et al. Association between a literature-based genetic risk score and cardiovascular events in women. JAMA. Feb 17 2010;303(7):631-637. PMID 20159871

20. Ripatti S, Tikkanen E, Orho-Melander M, et al. A multilocus genetic risk score for coronary heart disease: case-control and prospective cohort analyses. Lancet. Oct 23 2010;376(9750):1393-1400. PMID 20971364

21. Dandona S, Stewart AF, Chen L, et al. Gene dosage of the common variant 9p21 predicts severity of coronary artery disease. J Am Coll Cardiol. Aug 3 2010;56(6):479-486. PMID 20670758

22. Patel RS, Su S, Neeland IJ, et al. The chromosome 9p21 risk locus is associated with angiographic severity and progression of coronary artery disease. Eur Heart J. Dec 2010;31(24):3017-3023. PMID 20729229

23. Davies RW, Dandona S, Stewart AF, et al. Improved prediction of cardiovascular disease based on a panel of single nucleotide polymorphisms identified through genome-wide association studies. Circ Cardiovasc Genet. Oct 1 2010;3(5):468-474. PMID 20729558

24. Beckie TM, Groer MW, Beckstead JW. The relationship between polymorphisms on chromosome 9p21 and age of onset of coronary heart disease in black and white women. Genet Test Mol Biomarkers. Jun 2011;15(6):435-442. PMID 21375403

25. Beckie TM, Beckstead JW, Groer MW. The association between variants on chromosome 9p21 and inflammatory biomarkers in ethnically diverse women with coronary heart disease: a pilot study. Biol Res Nurs. Jul 2011;13(3):306-319. PMID 21705410

26. Dutta A, Henley W, Lang IA, et al. The coronary artery disease-associated 9p21 variant and later life 20-year survival to cohort extinction. Circ Cardiovasc Genet. Oct 2011;4(5):542-548. PMID 21852414

27. Shiffman D, O'Meara ES, Rowland CM, et al. The contribution of a 9p21.3 variant, a KIF6 variant, and C-reactive protein to predicting risk of myocardial infarction in a prospective study. BMC Cardiovasc Disord. 2011;11:10. PMID 21406102

28. Wang W, Peng WH, Lu L, et al. Polymorphism on chromosome 9p21.3 contributes to early-onset and severity of coronary artery disease in non-diabetic and type 2 diabetic patients. Chin Med J (Engl). Jan 2011;124(1):66-71. PMID 21362310

29. Ardissino D, Berzuini C, Merlini PA, et al. Influence of 9p21.3 genetic variants on clinical and angiographic outcomes in early-onset myocardial infarction. J Am Coll Cardiol. Jul 19 2011;58(4):426-434. PMID 21757122

30. Szpakowicz A, Kiliszek M, Pepinski W, et al. Polymorphism of 9p21.3 locus is associated with 5-year survival in high-risk patients with myocardial infarction. PLoS One. 2014;9(8):e104635. PMID 25105296

31. Szpakowicz A, Pepinski W, Waszkiewicz E, et al. Polymorphism of 9p21.3 locus is associated with 5-year survival in high-risk patients with myocardial infarction. PLoS One. 2013;8(9):e72333. PMID 24069144

32. Anderson CD, Biffi A, Rost NS, et al. Chromosome 9p21 in ischemic stroke: population structure and meta-analysis. Stroke. Jun 2010;41(6):1123-1131. PMID 20395606

33. Traylor M, Farrall M, Holliday EG, et al. Genetic risk factors for ischaemic stroke and its subtypes (the METASTROKE collaboration): a meta-analysis of genome-wide association studies. Lancet Neurol. Nov 2012;11(11):951-962. PMID 23041239

34. Dichgans M, Malik R, Konig IR, et al. Shared genetic susceptibility to ischemic stroke and coronary artery disease: a genome-wide analysis of common variants. Stroke. Jan 2014;45(1):24-36. PMID 24262325

35. Ni X, Zhang J. Association between 9p21 genomic markers and ischemic stroke risk: evidence based on 21 studies. PLoS One. 2014;9(3):e90255. PMID 24625579

36. Chou SH, Shulman JM, Keenan BT, et al. Genetic susceptibility for ischemic infarction and arteriolosclerosis based on neuropathologic evaluations. Cerebrovasc Dis. 2013;36(3):181-188. PMID 24135527

37. Olsson S, Jood K, Blomstrand C, et al. Genetic variation on chromosome 9p21 shows association with the ischaemic stroke subtype large-vessel disease in a Swedish sample aged </= 70. Eur J Neurol. Feb 2011;18(2):365-367. PMID 20500804

38. Yue X, Tian L, Fan X, et al. Chromosome 9p21.3 Variants Are Associated with Cerebral Infarction in Chinese Population. J Mol Neurosci. Feb 11 2015. PMID 25665551

39. Alg VS, Sofat R, Houlden H, et al. Genetic risk factors for intracranial aneurysms: a meta-analysis in more than 116,000 individuals. Neurology. Jun 4 2013;80(23):2154-2165. PMID 23733552

40. Thompson AR, Golledge J, Cooper JA, et al. Sequence variant on 9p21 is associated with the presence of abdominal aortic aneurysm disease but does not have an impact on aneurysmal expansion. Eur J Hum Genet. Mar 2009;17(3):391-394. PMID 18854858

41. Helgadottir A, Thorleifsson G, Magnusson KP, et al. The same sequence variant on 9p21 associates with myocardial infarction, abdominal aortic aneurysm and intracranial aneurysm. Nat Genet. Feb 2008;40(2):217-224. PMID 18176561

42. Bown MJ, Braund PS, Thompson J, et al. Association between the coronary artery disease risk locus on chromosome 9p21.3 and abdominal aortic aneurysm. Circ Cardiovasc Genet. Oct 2008;1(1):39-42. PMID 20031540

43. Biros E, Cooper M, Palmer LJ, et al. Association of an allele on chromosome 9 and abdominal aortic aneurysm. Atherosclerosis. Oct 2010;212(2):539-542. PMID 20605023

44. Wei Y, Xiong J, Zuo S, et al. Association of polymorphisms on chromosome 9p21.3 region with increased susceptibility of abdominal aortic aneurysm in a Chinese Han population. J Vasc Surg. Dec 20 2013. PMID 24365123

45. Lederle FA, Johnson GR, Wilson SE, et al. The aneurysm detection and management study screening program: validation cohort and final results. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators. Arch Intern Med. May 22 2000;160(10):1425-1430. PMID 10826454

46. Wei Y, Xiong J, Zuo S, et al. Association of polymorphisms on chromosome 9p21.3 region with increased susceptibility of abdominal aortic aneurysm in a Chinese Han population. J Vasc Surg. Apr 2014;59(4):879-885. PMID 24365123

47. Murabito JM, White CC, Kavousi M, et al. Association between chromosome 9p21 variants and the ankle-brachial index identified by a meta-analysis of 21 genome-wide association studies. Circ Cardiovasc Genet. Feb 1 2012;5(1):100-112. PMID 22199011

48. O'Donnell CJ, Kavousi M, Smith AV, et al. Genome-wide association study for coronary artery calcification with follow-up in myocardial infarction. Circulation. Dec 20 2011;124(25):2855-2864. PMID 22144573
49. van Setten J, Isgum I, Smolonska J, et al. Genome-wide association study of coronary and aortic calcification implicates risk loci for coronary artery disease and myocardial infarction. Atherosclerosis. Jun 2013;228(2):400-405. PMID 23561647

50. Zhang X, Wen F, Zuo C, et al. Association of genetic variation on chromosome 9p21 with polypoidal choroidal vasculopathy and neovascular age-related macular degeneration. Invest Ophthalmol Vis Sci. Oct 2011;52(11):8063-8067. PMID 21896860

51. Cesana F, Nava S, Menni C, et al. Does the 9p region affect arterial stiffness? Results from a cohort of hypertensive individuals. Blood Press. Oct 2013;22(5):302-306. PMID 23445356

52. Sturiale CL, Fontanella MM, Gatto I, et al. Association between polymorphisms rs1333040 and rs7865618 of chromosome 9p21 and sporadic brain arteriovenous malformations. Cerebrovasc Dis. 2014;37(4):290-295. PMID 24820060

53. Bendjilali N, Nelson J, Weinsheimer S, et al. Common variants on 9p21.3 are associated with brain arteriovenous malformations with accompanying arterial aneurysms. J Neurol Neurosurg Psychiatry. Nov 2014;85(11):1280-1283. PMID 24777168

54. Folsom AR, Pankow JS, Li X, et al. No association of 9p21 with arterial elasticity and retinal microvascular findings. Atherosclerosis. Oct 2013;230(2):301-303. PMID 24075760

55. Paynter NP, Chasman DI, Buring JE, et al. Cardiovascular disease risk prediction with and without knowledge of genetic variation at chromosome 9p21.3. Ann Intern Med. Jan 20 2009;150(2):65-72. PMID 19153409

56. Talmud PJ, Cooper JA, Palmen J, et al. Chromosome 9p21.3 coronary heart disease locus genotype and prospective risk of CHD in healthy middle-aged men. Clin Chem. Mar 2008;54(3):467-474. PMID 18250146

57. Brautbar A, Ballantyne CM, Lawson K, et al. Impact of adding a single allele in the 9p21 locus to traditional risk factors on reclassification of coronary heart disease risk and implications for lipid-modifying therapy in the Atherosclerosis Risk in Communities study. Circ Cardiovasc Genet. Jun 2009;2(3):279-285. PMID 20031596

58. Sposito AC, Ramires JA, Jukema JW, et al. Physicians' attitudes and adherence to use of risk scores for primary prevention of cardiovascular disease: cross-sectional survey in three world regions. Curr Med Res Opin. May 2009;25(5):1171-1178. PMID 19323611

59. Sheridan SL, Crespo E. Does the routine use of global coronary heart disease risk scores translate into clinical benefits or harms? A systematic review of the literature. BMC Health Serv Res. 2008;8:60. PMID 18366711

60. Do R, Xie C, Zhang X, et al. The effect of chromosome 9p21 variants on cardiovascular disease may be modified by dietary intake: evidence from a case/control and a prospective study. PLoS Med. Oct 2011;8(10):e1001106. PMID 22022235

61. Gransbo K, Almgren P, Sjogren M, et al. Chromosome 9p21 genetic variation explains 13% of cardiovascular disease incidence but does not improve risk prediction. J Intern Med. Sep 2013;274(3):233-240. PMID 23480785

62. Downing KP, Nead KT, Kojima Y, et al. The combination of 9p21.3 genotype and biomarker profile improves a peripheral artery disease risk prediction model. Vasc Med. Feb 2014;19(1):3-8. PMID 24323119

63. Goff DC, Jr., Lloyd-Jones DM, Bennett G, et al. 2013 ACC/AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. Jul 1 2014;63(25 Pt B):2935-2959. PMID 24239921

64. Recommendations from the EGAPP Working Group: genomic profiling to assess cardiovascular risk to improve cardiovascular health. Genet Med. Dec 2010;12(12):839-843. PMID 21042222.

65. UpToDate. Overview of the possible risk factors for cardiovascular disease. Literature review current through April 2016.

66. Wilson WF, MD, Overview of the possible risk factors for cardiovascular disease. In: UpToDate, Cannon CP, MD, Downey BP, MD (Eds), UpToDate, Waltham, MA. (Accessed on February 6. 2018.)

67. Wilson PWF. Overview of the possible risk factors for cardiovascular disease. In: UpToDate, Cannon CP, Givens J, Downey BC. (Eds), In UpToDate, Waltham, MA. (Accessed on January 29, 2019)

Codes:
(The list of codes is not intended to be all-inclusive and is included below for informational purposes only. Inclusion or exclusion of a procedure, diagnosis, drug or device code(s) does not constitute or imply authorization, certification, approval, offer of coverage or guarantee of payment.)

CPT*

81479

G0452