HLA-DRB1 and systemic sclerosis: The HLA-DRB1*11 allele was found to be strongly associated with SSc risk in the non-familial cohort, whereas HLA-DRB1*12 was found to be protective; however, it partially explains the disease clustering in familial SSc patients, suggesting the role of many other factors such as non-HLA genes, epigenetics, and environmental factors, which needs to be further investigated.