Amanda Spurdle

The Y chromosome as a tool for studying human evolution.

The use of the Y chromosome in human evolutionary research has only recently begun to gain momentum, partly because of a paucity of polymorphism. Differences in male/female behaviour patterns and the unique mode of inheritance of the Y chromosome also complicate interpretation of the data on Y chromosome variation.

The High Frequency of the Hb B2 Variant in the Herero Population: A Founder Effect?

The beta-globin gene cluster haplotype associated with the delta-globin variant Hb B2 was determined in Herero individuals from six different families, in order to establish whether founder effect was responsible for the high frequency of this variant in the population. The electrophoretic detection of Hb B2 was confirmed at the molecular level by polymerase chain reaction, followed by Cfo I digestion. The haplotype associated with the Hb B2 chromosome was determined in two families, and was shown to be the same. In the remaining four families the haplotypes could not be established conclusively, but were consistent with the haplotype observed in the other two families. The high gene frequency of Hb B2 is thus likely to have resulted form founder effect.

The Y-Specific p21A1/Taql Polymorphism Occurs in Four Major Population Groups

The p21A1/TaqI polymorphism was studied in 904 individuals in 23 African population groups, encompassing the Caucasoid, Negroid, Khoisan and Pygmy populations. The frequency of the polymorphism was higher than previously reported, with the rarer allele occurring at frequencies ranging up to 0.41. No distinct trends in population frequency were observed, suggesting that the polymorphism is of little value in anthropological population studies. The existence of several TaqI mutations, in both time and position within the repeat unit, is indicated.

The Inverted Y-Chromosome Polymorphism in the Gujarati Muslim Indian Population of South Africa Has a Single Origin

Y-specific polymorphisms were studied in Gujarati Muslim Indians possessing a Y-chromosome pericentric inversion [inv(Y)] in an attempt to prove a common genetic origin for the inversion. The p49a/TaqI and p49a/PvuII haplotypes were determined for 9 normal and 8 inv(Y) Gujarati Muslim men. Men with the inversion possessed identical TaqI and PvuII profiles, as opposed to 7 different TaqI and 8 different PvuII haplotypes observed in the 9 normal men. These results provide conclusive evidence for a common genetic origin of the inverted Y chromosome observed in this Gujarati Muslim community.

The Y-Specific pDP31 Rearrangement Polymorphism in Southern African Populations

The pDP31 rearrangement polymorphism was studied in 353 individuals encompassing the southern African Khoisan, Negroid and Caucasoid populations. The three alleles representing the ancestral (unrearranged) DNA configuration, the duplication, and the triplication were detected in most of the populations studied. The duplication occurred at higher frequencies in Caucasoid groups than in African populations, whilst the triplication was most common in Negroids. Populations of mixed ancestry exhibited allele frequencies closer to Caucasoids than to Negroids, in accordance with their historical origins.