LINKAGE OF ESSENTIAL-HYPERTENSION TO THE ANGIOTENSINOGEN LOCUS IN MEXICAN-AMERICANS

Essential hypertension has been linked to a highly polymorphic marker at the angiotensinogen locus, and association with a polymorphism in t his locus has been found in some populations. We tested the hypothesis that these same polymorphic markers are linked to essential hypertens ion in Mexican Americans. The data comprised all the affected relative pairs in 46 extended families chosen at random from a low-income barr io in San Antonio. Specifically, we searched for linkage by testing fo r excessive marker alleles shared identical by descent (LED) among hyp ertensive relative pairs. When women taking oral contraceptives or hor mones were excluded, the affected relative pairs shared a significant excess of alleles IBD for the highly heterozygous GT repeat polymorphi sm (P=.038) and were marginally significant for the M235T variant (P=. 079), which has a much lower heterozygosity (0.43 versus 0.85 for the GT repeat). We also assayed plasma levels of angiotensinogen and, usin g likelihood methods, found no significant association (P=.43) between plasma levels of angiotensinogen and M235T genotypes. These results s upport the linkage of essential hypertension to the angiotensinogen lo cus but do not indicate a specific role for the M235T variant.