July 16, 2007

Genetic heritage of an Afrikaner

I did not have time to read this paper fully, but this may signal the shape of things to come in the field of genetic testing. Until now, people could find something about their individual ancestors in the patrilineal (for men) or matrilineal (for both men and women) line of descent, and they could also get a rough estimate of their ancestral proportions from different population groups. Eventually it may become possible to determine not only the fraction of one's ancestry that derives from some population group but also get an estimate of when and where individual ancestors along all lines of descent lived. Ultimately a mega-genealogical tree for all mankind could -in principle- be constructed.

Ann Hum Genet. 2007 May 22; [Epub ahead of print]

Deconstructing Jaco: Genetic Heritage of an Afrikaner.

Greeff JM.
Department of Genetics, University of Pretoria, Pretoria 0002, South Africa.
It is often assumed that Afrikaners stem from a small number of Dutch immigrants. As a result they should be genetically homogeneous, show founder effects and be rather inbred. By disentangling my own South African pedigree, that is on average 12 generations deep, I try to quantify the genetic heritage of an Afrikaner. As much as 6% of my genes have been contributed by slaves from Africa, Madagascar and India, and a woman from China. This figure compares well to other genetic and genealogical estimates. Seventy three percent of my lineages coalesce into common founders, and I am related in excess of 10 times to 20 founder ancestors (30 times to Willem Schalk van der Merwe). Significant founder effects are thus possible. The overrepresentation of certain founder ancestors is in part explained by the fact that they had more children. This is remarkable given that they lived more than 300 years (or 12 generations) ago. DECONSTRUCT, a new program for pedigree analysis, identified 125 common ancestors in my pedigree. However, these common ancestors are so distant from myself, paths of between 16 and 25 steps in length, that my inbreeding coefficient is not unusually high (f (approx) 0.0019).


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