 Most people with coeliac bear a two-gene HLA-DQ2 haplotype referred to as DQ2.5 haplotype.This haplotype is composed of two adjacent gene alleles, DQA1*0501 and DQB1*0201, which encode the two subunits, DQ α5 and DQ β2.In most individuals, this DQ2.5 isoform is encoded by one of two chromosomes 6 inherited from parents (DQ2.5cis).