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Genetics

Genetics of Heart Disease 

  • Since all patients with heart attack from plaque rupture have coronary atherosclerosis (heart disease), but only a few with heart disease develop heart attack, unique factors—some genetic—are likely to predispose to plaque rupture or heart attack in coronary atherosclerosis.1
  • Recent genomewide association studies indicate that genetic factors predisposing to heart attack in patients with heart disease are distinct from those that associate with the presence of heart disease.1 Having ABO blood group O may reduce the risk of heart attack by up to 20%. 
  • Reilly and colleagues compared 12,393 individuals with coronary artery disease (CAD) with 7383 controls (without any narrowing on angiography) and identified a new locus, ADAMTS7, to be a common genetic risk factor for heart disease, with a 19% increased risk for carriers.1
  • Nine genome wide studies have found 14 chromosomal loci at which one or more common single nucleotide polymorphisms (SNPs) are associated with CAD or heart attack. Almost all these studies have implicated the 9p21.3 locus, considered as the most widely and consistently replicated genetic risk factor for CAD. But still much of the genetic risk that underlies the development of CAD and heart attacks is unexplained by common risk SNPs.1 
  • Using 1200 genome-wide polymorphisms in 432 individuals from 15 Indian language groups, Riley et al have recently shown that Indians constitute a distinct population-genetic cluster. Despite the geographic and linguistic diversity of the groups they exhibit a relatively low level of genetic heterogeneity.2
  • Caution is needed when treating the Asian Indian population as a single population in genetic studies using SNPs. The overall difference in minor allele frequency of the polymorphisms investigated was small between the different language groups.2
  • The high prevalence of endogamy and relatively low admixture distinguishes South Asians from most other populations presently used in genetic studies as it represents a distinct genetic background that is largely unaffected by outside admixture.2
  • Asian Indians exhibit unique genotype as well as phenotype (see Malignant Heart Disease) characteristics that may yield new insight into the underlying causes of diseases that are not available in other populations.

Sources 

1.Reilly M P, Li M, He J, et al. Identification of ADAMTS7 as a novel locus for coronary atherosclerosis and association of ABO with myocardial infarction in the presence of coronary atherosclerosis: two genome-wide association studies. Lancet. Jan 29 2011;377(9763):383-392.

2.Pemberton T, Mehta NU, Witonsky D, et al. Prevalence of common disease-associated variants in Asian Indians. BMC Genet. 2008;9:13. 

 

 

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