DIRECT ROLE OF HLA-B5 IN INFLUENCING SUSCEPTIBILITY TO TAKAYASU AORTOARTERITIS

To investigate genetic factors involved in the pathogenesis of Takayas u arteritis (TA), North Indian patients belonging to the states of Pun jab, Haryana, Uttar Pradesh and Delhi were examined for HLA-class I an d class II antigens and the data compared with healthy controls from t he same ethnic group. Additionally, DNA typing was performed using pol ymerase chain reaction/sequence specific oligonucleotide probe (PCR-SS OP) technique to evaluate the distribution of molecular alleles in the healthy Indian population as compared to orientals and Western caucas oids. The frequency of HLA-BS was significantly increased in patients as compared to controls (chi(2) = 32.5, corrected P value, P-c = 3 x 1 0(-6), relative risk = 4.3). serological splitting of B5 into B51 and B52 did not reveal an association with any of the two subtypes, Weak a ssociation was also noticed with DR8 in the patient group (chi(2) = 8. 2, P-c = 0.05). Distribution of the molecular subtypes of various HLA- B and DR alleles indicated that although the Indian population is esse ntially caucasoid, it comprises of an admixture of both caucasoid as w ell as oriental alleles/haplotypes. The observations clearly suggest t hat (a) HLA-linked genes are involved in the development of Takayasu a rteritis, and (b) rather than a subtype of B5, the whole molecule or i ts closely linked gene(s) influence susceptibility to TA.