Homozygotes at DQ loci can change risk for disease. In mice for instance, mice with 2 copies of the DQ-like Iab haplotype are more likely to progress toward fatal disease compared to mice that are heterozygotes only for the beta allele (MHC IAαb / IAαb, IAβb / IAβbm12). In humans, celiac disease DQ2.5/DQ2 homozygotes are several times more likely to have celiac disease versus DQ2.5/DQX individuals. DQ2/DQ2 homozygotes are at elevated risk for severe complications of disease. For an explanation of the risk association see: