HLA-DR3-DQ2 is found in HLA A1-B8-DR3-DQ2 haplotype in Northern Europeans (including the British Ilse, Ireland, Iceland).

DQB1*0202 is not genetically linked to DQA1*0501 and its cis-haplotype isoform infrequently mediates coeliac disease or type 1 diabetes.

It has a substantially higher frequency in the western world, except indigenous Native American (see tables).

[Note some population test DR3 or DQA1:DQB1, the DR3-DQ2 serotype is generally synonymous in frequency with DQ2.5] DR3-DQ2 probably originated from Central or West Africa.

There is the possibility it spread to Arabia, but through stepwise expansion of small groups was lost from the DQ genetic repertoire.

Other evidence for a west African origin/expansion is seen with the probable origin of DQA1*0501 from DQA1*0505, which is at relatively high frequencies in west-central Africa.

European DR3-DQ2 is ancestrally derived from Africa, probably from Southwestern Europe or the Levant (in which DQ2.5 may have undergone negative, coeliac disease, selection during the holocene).

DR3-DQ2 was probably the predominant HLA haplotype in the early holocene Western and Central Europe, archaeological studies of France, particularly of the Paris Basin region indicate a cultural shift that occurs as a result of the neolithic revolution.

Because of the central location of the anti-node, the center of expansion of DR3-DQ2 with the recolonization of western Europe after the last glacial maximum has been obscured.

Despite its high frequency Ireland is not likely the source of the haplotype in European, but a region that has been least disturbed by the negative selection of wheat culture and migrations.

Ironically, there is no convincing route of travel between West Africa and Central Asia suggested by gene frequencies in the peoples between the two.

One eastern haplotype is "A33-B58" and has some punctuated distribution in Western Europe at relatively low levels, and is also in extreme disequilibrium where it is found, elsewhere.

DR3-DQ2 presence in the Koreans and lack thereof in the Japanese suggest a recent spread into Western Pacific Rim of Asia.

The knowledge of frequencies in populations, particularly among ancestors of immigrants can aid patient and physician as to the potential risks.

[53] An example, one publication states that the western regions of Ireland have the highest coeliac disease rate in the world.

The DQA1*0501:DQB1*0201 (DQ2.5) locus confers susceptibility to Gluten Sensitive Enteropathy (GSE)and (Type 1 Diabetes) but has also been linked to other rarer autoimmune diseases like myasthenia gravis.