HLA-A1

HLA-A1 (A1) is an HLA-A serotype. The serotype identifies the more common HLA-A*01 gene products. A1 is more common in Europe than elsewhere, it is part of a long haplotype that appears to have been frequent in the ancient peoples of Northwestern Europe. Part of this haplotype is A1-Cw7-B8 (its serotype name), which has a frequency mode in Ireland where it is the highest frequency A-Cw-B type in Europe.

Serotype
The serotyping capability of the A1 serotype is excellent. For the A1 group there are 24 alleles, 7 nulls, 14 protein variants. Two alleles, A*0101 and A*0102, comprise the overwhelming majority of alleles.

By allele
A*0101 appears to alter risk for type 1 diabetes. Because A*0101 is linked to DR3-DQ2.5 (see below), and because this class II haplotype has a bearing on diabetes risk (2nd most potent risk factor) some of this risk could be due to linkage with DR3.

By haplotype
A1-B58 (A1-B17 where B58 is dominant) is associated with antineutrophil cytoplasmic antibodies (ANCA)

A-B Haplotypes

 * A1-B7 Armenia, Austria, NW Europe (regional recombinant between A1-B8 and A2/A3-B7)
 * A1-B13 Uralic
 * A1-B35 (Albania, Belgium, Italy, Greece, France - Eastern mediterranian in origin)
 * A1-B37 Yakuts, Tribal-India, Iyers-India, Mongolian, Indian, Orochon, Romanian, Yugoslavia, Korean, Albania, French, German, Manchu
 * A1-B51 Yugoslavia, Germany, Iberia, Italy
 * A1-B52 Bharghavas-India, Tribal-India, Italy, Iberia, France
 * A1-B57 (See tables on discussion page)
 * A1-B58 (See tables on discussion page)

A1-Cw7-B8
A1-Cw7-B8 is the multi-serotype designation for the haplotype HLA-A*0101:C*0701:B*0801, the class I portion, of the "Super B8 Haplotype" ancetral "Ancestral Haplotype" (A1-B8-DR17(3)-DQ2.5). The full haplotype is (for relative distances see Human leukocyte antigens:

A*0101 : C*0701 : B*0801 : DRB1*0301 : DQA1*0501 : DQB1*0201

The frequency node for this haplotype is in Western Ireland. Where as the most allelic diversity (variations of A*01 or B*08 are within East Africa. The Cw7 locus carries several variants Europe (Cw*0701) Africa (Cw*0701 & Cw*0704) It suprisingling maintains DR linkage, over 2 million nt distance is still shows relative linkage disequilibrium with DR3. In NW Europe linked to DRB1*0301 and in  SE Europe DRB1*0301/*0302. It is also disequilibrated in its linkage to DQ2, and in NW Europe it is linked to DQA1*0501:DQB1*0201. Because of the incredible linkage disequilibrium this haplotype is believed to have been under positive selection in Europe's prehistoric period. When DR or DQ typing is not present for a population this haplotype can substitute as a marker for DQ2.5 abundance and coeliac disease risk, as in the case for Ireland.

The rightmost column in the table on the right shows the rank of A1-B8 in A-B haplotypes, it is the most common top ranked haplotype in Western Europe, in fact it is one of the more common A-B haplotypes in the world.