Serogenetic studies on the inhabitants of Tristan da Cunha

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Abstract
The inhabitants of Tristan da Cunha, a remote island in the South Atlantic, number .apprx. 300 and are direct descendants of a small number of individuals who settled there in the 1st half of the 19 century. Some serogenetic studies were carried out on the islanders when they were evaculated to England [UK] in 1961, but 160 individuals have now been tested for a much wider range of gene markers. No variation was found at 15 loci while considerable variation was encountered at 12 loci. In particular, the high frequency of A1 and the complete absence of A2 in the ABO system was confirmed; the high frequency of R0 (cDe) in the Rhesus system and GdA, an allele at the G6PD [glucose-6-phosphate dehydrogenase] locus, as well as the presence of 3 haplotypes in the Gm system (Gm1,,5,6,14,17, Gm1,6,17 Gm1,5,13,14 ,17) confirm the known historical origin of the women founders who came from St. Helena. Although the degree of inbreeding is high, there is no significant deficiency of heterozygotes in the 8 informative systems.