TLR1 and HLA-DRB1/DQA1 as major leprosy susceptibility genes.

The hydrophilic serine substitution (TLR1 I602S) is result of mutation and is rare in Africa and Asia, but a significant proportion of individuals of European descent are homozygous for this knockout variant. These functional TLR1 knockout individuals have a normal immunological phenotype and are protected against leprosy, suggesting that M. leprae may have utilized TLR1 as part of its pathogenesis mechanisms.