HLA-DRB1 and systemic sclerosis: Additionally, DRB1*07:01 haplotypes can carry either DQB1*02:02 (+3) or DQB1*03:03 (0), and there was no suggestion of skewed paternal inheritance for these two haplotypes or an increase in DRB1*07:01–DQB1*02:02 haplotypes in the SSc population overall (Additional file 1: Table S1).