The aim of this proposal is to complete the analysis of an extensive body of data relating to the familial aggregation of diabetes, its risk factors, and association with other diseases and traits collected in the course of an epidemiological study of the Mexican-American population of Starr County, Texas. Data collection (completed June 1983) resulted in two related data bases: (1) a random sample of 1930 individuals to establisch diabetes prevalence and identify probands and (2) comprenhensive physical examinations (including ophthalmic and physical examination, evaluation of peripheral neuropathy, EKG, anthropometric measurements, historical appraisal of medication, fertility, disease experience, smoking and drinking, and laboratory determination of fasting glucose, glycohemoglobin, hemoglobin, hematocrit, cholesterol, HDL, and some 39 genetic markers) on 155 diabetic probands and 135 of their relative (largely first degree). We have shown that this population has a diabetes prevalence which is three to five times that of the U.S. population at large. Further, over 50% of the county population 35 years and above are either a diabetic or a first degree relative of one; thus being economically and psychosocially burdened and at increased risk. Our analytical objectives include evaluating the genetic and environmental contributions to the familial aggregation of diabetes by testing for the affects of polygenes, common environmental affects and major genes as well as testing for marker associations and linkage. Further, we will evaluate the role of these same factors in the coaggregation of diabetes, obesity and hypertension to determine whether they are causally related, multiple manifestations of a common underlying mechanisms, or whether they are genetically independent and environmentally related. We will also assess the role of genetic admixture with other Amerindian populations as a possible source of the increased diabetes rate in this population. Finally, the 261 diabetics for whom we have extensive data will allow assessing the natural history of diabetes and development of retinopathy in th is population. The insights so provided should aid materially in the allocation of health care resources and facilities, the recognition of specific health educational needs and the delineation of the role of population studies and family follow-up in screening programs.
