BACKGROUND:

Although the familial clustering of coronary heart disease has been well documented, it is unclear as to whether the familial clustering can be explained by shared environmental factors by members of a family or by clustering of risk factors having a genetic component such as blood pressure, familial hyperlipidemia and/or diabetes. Studies indicate that a family history of coronary disease may be an independent risk factor. Major histocompatibility complex genetic markers to identify individuals at risk within a family may be useful. In 1985 when the study began, there was a paucity of data dealing with the interrelationship of family history, genetic markers, immunological markers, and traditional risk factors.

DESIGN NARRATIVE:

In this case-control study, the study population consisted of incident cases who presented to the Georgia Heart Clinic in La Grange, Georgia with coronary heart disease. The majority of the subjects were from three counties in mideastern Alabama and from counties in midwestern Georgia. All subjects had undergone diagnostic coronary angiography. A determination was made in patients and controls of the association of major histocompatibility complex genetic markers HLA-A, -B, -C, -DR, C4 and BF, C3, the restriction fragment length polymorphisms (RFLP's) flanking the apolipoprotein AI and insulin genes, presence of autoantibodies, and family history of coronary disease, diabetes, or hypothyroidism. The frequency of these variables was compared with the standard coronary risk factors of family history, hypertension, lipid abnormalities, lifestyle, Type A behavior, obesity and with diseases such as diabetes and hypothyroidism. An analysis was made of the strength of these variables for predicting those individuals at risk and whether there were variables which predict severity of disease based on 1, 2, or 3 vessel involvement.