Soodyall Himla, Nebel Almut, Morar Bharti, Jenkins Trefor
1MRC/NHLS/Wits Human Genomic Diversity and Disease Research Unit, Division of Human Genetics, School of Pathology, National Health Laboratory Service and University of the Witwatersrand, PO Box 1038, Johannesburg 2000, South Africa.
Eur J Hum Genet. 2003 Sep;11(9):705-9. doi: 10.1038/sj.ejhg.5201022.
The island population of Tristan da Cunha has a well-documented genealogy that dates to its first permanent settlement in 1816. The current population is thought to have descended from only seven females and eight males. Today, there are seven family names in use, corresponding to the number of founding fathers with present-day male descendents. Y chromosome polymorphisms have previously been shown to be reliable tools for tracing patrilineal genealogies. Here, we studied Y chromosome polymorphisms in a sample from Tristan da Cunha together with genealogical records to (i) infer the haplotypes of the seven founders and (ii) test if the Y chromosome transmission is consistent with the documented patrilineal history of the island community. We observed nine Y chromosome haplotypes of which seven could be traced to the known ancestors. Of the two additional lineages, one probably evolved from a founder haplotype due to a single-step microsatellite mutation, while the other had an obvious non-island origin. Its introduction, however, is not reflected in the records. Four more instances of non-paternity were identified, with the "new" chromosomes matching other island haplotypes. The Y chromosome data presented here question the validity of some of the genealogical documentation and emphasise the value of genetic studies in tracing ancestry.
特里斯坦-达库尼亚群岛的岛民有着有据可查的家族谱系，其历史可追溯到1816年的首次永久定居。据信，目前的人口仅由7名女性和8名男性繁衍而来。如今，该岛使用的姓氏有7个，与拥有现今男性后代的开国元勋人数相对应。此前已证明，Y染色体多态性是追溯父系家族谱系的可靠工具。在这里，我们研究了来自特里斯坦-达库尼亚群岛的一个样本中的Y染色体多态性，并结合家族记录来（i）推断7位奠基者的单倍型，以及（ii）检验Y染色体的传递是否与该岛社区有记录的父系历史一致。我们观察到9种Y染色体单倍型，其中7种可以追溯到已知的祖先。在另外两个谱系中，一个可能是由于单步微卫星突变从奠基者单倍型进化而来，而另一个则明显有非该岛的起源。然而，其引入并未在记录中体现。我们还发现了另外4例非父系遗传的情况，“新的”染色体与该岛的其他单倍型相匹配。这里呈现的Y染色体数据对一些家族记录的有效性提出了质疑，并强调了基因研究在追溯祖先方面的价值。
