RESUMEN
BACKGROUND: Longevity can be regarded as a multifactorial trait that results from an interaction between environmental factors and sets of epistatic alleles that have pleiotropic age-dependent effects. The Hotan district in the Xin Jiang Uighur Autonomous region of China is relatively isolated and is well known for an ethnic group that displays marked longevity. METHODS: We performed a correlation study between the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene and longevity by comparing distributions of the polymorphism between three different ethnic groups in this region. We obtained data from 424 subjects comprising 227 Uighur individuals, 108 Kazakh individuals, and 89 Han individuals. All subjects in the latter two groups ranged in age from 65 to 70 years, whereas the Uighur subjects actually comprised two different age groups: those ranging in age from 59 to 70 years (Uighur older group in Hotan [UOH]) and those ranging in age from 90 to 113 years (Uighur longevity group in Hotan [ULH]). Genomic DNA was extracted from peripheral white blood cells. Polymerase chain reaction was performed to amplify the I/D polymorphic region of the ACE gene. RESULTS: Frequencies of the insertion (I) and deletion (D) alleles were 0.596 (243/408) and 0.404 (165/408) in the Uighur group, 0.606 (130/216) and 0.394 (85/216) in the Kazakh group, and 0.657 (117/178) and 0.343 (61/178) in the Han group. The overall distributions of alleles in these three groups did not differ significantly (chi(2) = 4.6, p =.33). Within the Uighur group, frequency of the D allele was significantly higher in the ULH group (0.448) than in the UOH group (0.355) (p <.04). CONCLUSIONS: This association reflects a genetic influence on differential survival and may point to pleiotropic age-dependent effects on longevity. Our data may help elucidate the relationship between natural longevity and race difference among individuals in the Xin Jiang Uighur Autonomous region of China.