Genetic Structure of the HL‐A System in a Nahua Indian Population in Mexico

Abstract

HL–A phenotype and gene frequencies are presented for a population sample of Nahua Indians from Mexico. These Indians showed restricted variability in the first and second segregant HL–A series as compared to Caucasian, Black and Mongoloid populations, thus resembling other American Indian populations. Determinants for HL–A2, HL–A9, W28 and W31 accounted for 95% of first series alleles. For the second series W16, W5 and W10 comprised 75% of all genetic determinants. This population sample is the only American Indian group so far studied with W16 as the most frequently occuring second series antigen. Disturbances in the Hardy‐Weinberg equilibrium for the second series may reflect racial admisture and an antigen which cross reacts with W5 and W15. When adjustments were made for sample size and selection of the extreme deviate delta value, no evidence of linkage disequilibrium was noted in this population. Thus far, all American Indian groups studied show restricted variability of the HL–A system; this may reflect the effects of natural selection.

HLA Frequencies in a Mexican American Population

“…In agreement with the results of Albert et al (1972), we found A2 and Bw35 to be the most frequent HLA-A and HLA-B alleles in Mexican Americans from San Antonio, In fact, A2 has characteristically been the most frequent HLA-A allele in Caucasian as well as American Indian, Mexican and Mexican American populations (Albert et al 1972, Dausset & Colombani 1972, Cann et al, 1973Gorodezky et al 1979Gorodezky et al , 1972. In contrast to the results of previous studies of Mexican Americans (Albert et al 1972, Murray et al 1978 but in agreement with a recent study of Mexican Mestizos (Gorodezky et al 1979 meyer-Nielsen 1975, Spees et al 1975, Ward 1975), suggesting a Negroid component in the ancestry of Mexican Americans.…”

“…Similar differences in expression of these antigens between Mexican Americans and Caucasians were apparent in the results of Albert et al (1972). In the largest Mexican Indian population, the Nachuas, frequencies of A l , B7 and Bw35 were .067,135 and ,393, respectively (Cann et al 1973), while studies of other American Indian groups have similary revealed relatively low (or absent) frequencies of A1 and B7, and a preponderance of Bw35 (Dausset & Colombani 1972). These data together with ours, support the prevalent American Indian admixture in Mexican Americans.…”

“…The distribution of HLA antigens among various Mexican subgroups (i.e., Mexican Mestizos, Mexican Indians, Mexican Americans) has been the subject of previous reports by others (Gorodezky et al 1972, 1979, Escobar-GutiCrrez et al 1973, Cann et al 1973, Albert et al 1972, Murray et al 1978, Terasaki et al 1978. With the exception of the recent study by Gorodezky and co-workers (Gorodezky et al 1979), previous reports on HLA typing of Mexican subgroups were hampered either by the restricted range of reagent sera (Gorodezky et al 1972, Escobar-Gutierrez et al 1973.…”

“…With the exception of the recent study by Gorodezky and co-workers (Gorodezky et al 1979), previous reports on HLA typing of Mexican subgroups were hampered either by the restricted range of reagent sera (Gorodezky et al 1972, Escobar-Gutierrez et al 1973. C a m et al 1973 This is publication 27 from the Division of Urology, University of Texas Health Science Center at San Antonio, Texas, U.S.A. Albert et al 1972) or by the limited population size (Gorodezky et al 1972, Escobar-GutiCrrez et al 1973, Cann et al 1973, Albert et al 1972, Murray et al 1978). Here we have assessed HLA antigen representation in 300 unrelated Mexican Americans and, for comparison, 300 unrelated Causasians, all of whom reside in the San Antonio area.…”

HLA Antigens in South American Indians

“…These factors make the identification of endogenous types on the northern continent more difficult. In general, however, all the antigens which we have found in South America as well as types Bw21 and B27 occur in North American Indians in higher frequencies than in Europeans (Cann et al 1973, 1974, Perkins et al 1974, Troup et al 1974, Corley et A. 1974, Grofton et al 1975.…”