HLA-DQA1 and celiac disease: In the celiac disease HLA-DQ 2.5 heterodimers—encoded by DQA1*0501 and DQB1*0201/0202 alleles both in cis or trans configuration—and DQ8 molecules—encoded by DQB1*03:02 usually in combination with DQA1*03 variant—are known to be genetic susceptibility factors.