HLA segregation of tuberculoid leprosy: confirmation of the DR2 marker.

Families with multiple cases of leprosy were tested for HLA (histocompatibility leukocyte antigen)-linked control of susceptibility to tuberculoid leprosy and association with HLA-DR2. Thirty-one non-HLA genetic markers were also examined for indications of non-HLA-linked genetic factors that might control susceptibility to tuberculoid leprosy. A significant (P = 0.002) preferential inheritance of HLA-DR2 by siblings affected with tuberculoid leprosy, but not by healthy siblings nor by siblings affected with lepromatous leprosy, was observed. In addition, combined family data showed a significant (P less than 0.0025) excess of identical HLA haplotypes inherited from healthy parents by siblings affected with tuberculoid leprosy. Segregation on non-HLA polymorphisms did not deviate significantly from what would have occured randomly. These data are compatible with a recessive inheritance of HLA-linked susceptibility to tuberculoid leprosy. The preferential segregation of DR2 observed in children with tuberculoid leprosy (P less than 0.001 for the combined data from India) indicates that the HLA-linked susceptibility gene is either DR2 or in linkage disequilibrium with it.