GENETIC-CHARACTERIZATION OF AMERICAN AND WESTERN SAMOANS

The Samoan islands were politically separated into American Samoa and Western Samoa in the early 1900s. Economic modernization is far more e xtensive in American Samoa. However, the Samoan archipelago has mainta ined a remarkable degree of sociocultural homogeneity, including inter marriage. The sociocultural exchanges presumably led to genetic homoge neity between the two Samoas. Detailed genetic comparisons and charact erizations of Samoans are scanty, however. As part of a multidisciplin ary study of modernization and cardiovascular risk factors in adults, we analyzed nine hypervariable nuclear DNA (HVR) and four serum protei n polymorphisms in the two Samoan groups. The average heterozygosities at both DNA and serum protein loci are comparable in the two groups. As expected, the HVR loci reveal a high degree of variability (heteroz ygosity 30-87%) compared with the serum protein loci (heterozygosity 1 -52%). A large proportion of alleles at the HVR loci, ranging from 50% to 100%, are shared between American acid Western Samoa. With the exc eptions of the D1S80 locus in American Samoa and the D13S118 locus in Western Samoa, the genotype distributions at all loci conform to their respective Hardy-Weinberg expectations. Sporadic occurrence of the F1 3B2 allele at the F13B locus in Samoans indicates a low level of Euro pean admixture because this allele is unique to Europeans. The calcula ted zero values of kinship coefficients and standard genetic distances indicate minimal population differentiation between the two Samoan gr oups.