HLA and Disease Susceptibility in Tamil Nadu, S. India.

ABSTRACT

Result on HLA polymorphism in the populations of Tamil Nadu, South India are analysed for HLA association with various diseases like pulmonary tuberculosis, leprosy, psoriasis, rheumatoid arthritis, iridocyclitis and Eale's disearse. These studies revealed i) association of psoriasis with HLA B17 and DR7 is highly significant in Vellala related group and this is attributed to founder effect-hitch hiking of a disease producing gene linked to these alleles, as the population migrated, ii) different castes differ from one another in their HLA allelic and haplotype polymorphism, iii) HLA DR2 predispose for more severe from of pulmonary tuberculosis which transcends ethnic barrier, the susceptibility presumably being due to a generalized MHC dependent immunogenetic and pathological mechanism, iv) HLA B27 and DR4 are associated with iridocyclitis, rheumatoid arthritis and low back pain; the susceptibility may be a HLA dependent molecular mimicry process, v) HLA alleles DR2 and DR4 predispose for severe forms of the respective diseases, though not for initial susceptibility.