More on the mutation shared by the Vikings and the Jews.
Laura Spinney. "HIV protection via the Vikings?" BioMedNet News (July 23, 2003). Excerpts:
"A common genetic mutation that confers protection against HIV and possibly also multiple sclerosis and type 1 diabetes may have arisen over 1000 years ago in a lost kingdom in what is now Russia, according to an Australian geneticist. Marc Buhler of the Institute for Immunology and Allergy Research at the University of Sydney thinks that the delta32 deletion mutation in the CCR5 gene is now a target for selection because it protects against certain strains of HIV, but that initially it may have been selected for because carriers survived small pox... The CCR5-delta32 mutation is particularly common among Ashkenazi Jews... among Ashkenazis from Western Europe, for instance, it occurs with the same frequency as in Caucasian non-Jews... He then genotyped the 26 Ashkenazi Jewish individuals who turned out to be homozygous for the mutation, and measured the degree of recombination that had taken place in the region in which the mutation occurs to come up with an estimate of when the mutation first arose. To his surprise, his calculations generated an age of 50 generations, or just over 1000 years. The Ashkenazi Jews left Israel around 2000 years ago... Since the mutation is not common among the Sephardic Jews who stayed in the Middle East, and since it appears to be older than the Ashkenazis' Germanic period - the last time they were concentrated as a population - Buhler surmises that it had its origins elsewhere [other than Germany]. There were several other pieces to fit into the jigsaw: for instance, the incidence of CCR5-delta32 is relatively high among Scandinavians... When he gathered information about his Ashkenazi volunteers' forebears, he found that the frequency of the mutation leapt to 20% in a subgroup whose grandparents came from Russia or Eastern Europe - almost 10% higher than the frequency among Western European Ashkenazis... Since small pox kills around one third to a half of its untreated victims, Buhler says selection would have been very strong for CCR5-delta32 if heterozygotes did indeed avoid death... [U]pper class Khazars adopted Judaism in the mid-10th century... 'The Jewish Khazars had the main block of the mutation,' says Buhler, 'But a few [Khazar] slaves kidnapped by the Vikings would have been enough for them to take it away as a souvenir.' Khazaria ceased to exist around the 13th century, when it was absorbed by Russia, and from then on the Khazar Jews would have blended with the Ashkenazi ancestors of Buhler's Australian volunteers.""Geneticist finds Ashkenazi immunity." Australian Jewish News (August 22, 2003). Excerpts:
"...In a study of 1400 subjects, Marc Buhler found that Jews originating from Austria, Hungary, Czechoslovakia, Poland and Russia are prone to carry CCRS-delta 32 - a gene modifier that alters the immune system. ...Buhler said that the gene modifier fends off the symptoms of HIV/AIDS for anywhere between four years and a lifetime. ... Presented in Melbourne at the International Congress of Genetics, the study found CCRS-delta 32 in as many as 35 per cent of Jewish subjects originating from Austria, Hungary, Czechoslovakia, Poland and Russia. The proportion for non-Jewish subjects hailing from that part of the world was around 25 per cent. However, Jews from other parts of Europe, Asia and the Middle East are no more likely to carry the gene modifier than their non-Jewish counterparts from the same region, he said. CCRS-delta 32 was also discovered in nearly 30 per cent of subjects from Iceland - an observation that prompted Buhler to speculate that the mutation first emerged among medieval Russian Jewish communities and was spread to Northern Europe by the Vikings. Buhler believes that the first carrier of the gene mutation was probably born in Khazaria (in Southern Russia) between 800 and 1000AD. ... Buhler said that CCRS-delta 32 may have also protected Jews against the smallpox. The gene modifier has thrived, he said, because it can ward off adverse symptoms and keep carriers alive long enough to procreate."