HLA-DQA1 and celiac disease: Human leukocyte antigen (HLA) class II molecules on chromosome 6 are necessary factors for celiac disease where 90–95 % of all affected patients carry the HLA-DQA1*05:01-DQB1*02:01 haplotype and the remainder carry either the HLA-DQA1*03:01-DQB1*03:02 or HLA-DQA1*02:01-DQB1*02:02 haplotype [1].