HLA-DQ8 : distribution map, subtypes, SNPs and associated medical conditions

Maciamo

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Here is a map showing the allele frequency of HLA-DQ8. The world's highest frequencies are observed in Central and South America (up to 80%), then in Siberia (11-22%).

It has been suggested that a migration from people east of the Urals is responsible for DQ8. The strongest association with Y-chromosomal haplogroups appears to be with haplogroup Q, but it is possible that the Indo-Europeans (carrying haplogroups R1a and R1b) also spread this HLA type. In fact, I have checked ancient genomes from Haak et al 2015 for you, and while Mesolithic (Samara, Karelia) and Neolithic (LBK, Spain) samples are all negative for DQ8, one of the two Yamna and Corded Ware samples I checked each carried one copy of DQ8 allele.

In Europe, DQ8 peaks in the Sardinian population (22%), followed by Sweden (18.5%) and Finland (16.5%), then Norway, Denmark and Germany (all 13%). While Siberian ancestry (e.g. Y-haplogroups N1c, Q, and more distantly R1a and R1b) is noticeable in Germanic countries, it is extremely low in Sardinia. Sardinians may have acquired DQ8 from an intermediate source, and the allele could subsequently have propagated quickly due to the resistance it conferred to some local pathogens or diseases. Other Italians and the Basques (who are relatively close to the Sardinians genetically) have some of the lowest levels of DQ8 in Europe.

Levantine people also have high frequencies of DQ8. This is true for (both Ashkenazi and non-Ashkenazi) Jewish (18-22%), Jordanian (18%) and Lebanese (12%) people. All of these people have between 2 and 5% of Y-haplogroup Q1b, ultimately of Siberian origin. The Phoenicians are an ideal candidate for having brought DQ8 to Sardinia.


HLA-DQ8.png



SNP's


DQ8 is determined by the antibody recognition of β8 and this generally detects the gene product of DQB1*0302. This allele is encoded by the SNP rs7454108 (C means carrier). It is tested by 23andMe and FTDNA's Family Finder).

Medical conditions

Like DQ2, DQ8 is linked to coeliac disease. 12% of all people with coeliac have HLA-DQ8. It is also one of the main genetic risk factors for juvenile diabetes.
 
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