HLA AND LEPROSY - SEGREGATION AND LINKAGE STUDY

Background. The presence of a genetic factor in the determination of l eprosy has long been debated. This study tests whether the HLA-linked control of susceptibility to leprosy and/or for the types of leprosy c ould be confirmed. Materials and Methods. In 15 multicase families, th e method of DeVries et al., 1976, was used to detect nonrandom segrega tion of parental HLA haplotypes in their affected and healthy siblings . Linkage analyses, for two and three alleles were performed by the co mputer program LIPED, Results. For the affected siblings, the segregat ions of the parental HLA haplotype were significantly nonrandom from t he healthy parents and random from the affected parents, indicating th at affected siblings were sharing their HLA haplotypes (segregated fro m the healthy parents) more than expected. The segregations to the hea lthy siblings from both the healthy and affected parents were random. Healthy siblings inherited the haplotypes shared among the leprosy sib lings randomly as expected. There were excess DR(2)/DR(2) homozygote i ndividuals among tuberculoid siblings. The highest rod score was achie ved when we considered our suggested three-alleles model for the susce ptibility to the different types of leprosy. Conclusions. A closely HL a-linked gene on chromosome number 6 with multiple alleles (3 or more) in recombination fraction between 0.05 and 0.1 with 70 to 100% penetr ance may be responsible for the susceptibility to the different types of leprosy, whereas the susceptibility to leprosy per se maybe the res ponsibility of non-HLA linked gene/s. DR(2)/DR(2) homozygote individua ls may be relatively at high risk of developing leprosy or tuberculoid leprosy.