Association of functional mutant homozygotes of the mannose binding protein gene with susceptibility to pulmonary tuberculosis in India.

Abstract Setting : Mannose binding protein gene polymorphism in pulmonary tuberculosis in India. Objective : To find out whether non-HLA genes such as mannose binding protein (MBP) genes are associated in the susceptibility to pulmonary tuberculosis. Design : Genotyping of MBP 52, 54 and 57 wild and mutant alleles was carried out in HLA-DR typed pulmonary tuberculosis patients ( n =202) and control subjects ( n =109). Since HLA-DR2 is associated with pulmonary-TB, the interaction of MBP genes on -DR2 and non-DR2 genes on the susceptibility was also studied. Results : A significantly increased genotype frequency of MBP functional mutant homozygotes (including 52, 54 and 57) was seen in pulmonary tuberculosis (PTB) patients (10.9%) than in control subjects (1.8%; P =0.008; odds ratio: 6.5). Analysis of interaction of MBP genes and HLA-DR2 on the susceptibility to PTB revealed that these genes are associated with PTB independent of each other. Conclusion : The present study shows that functional mutants of MBP are associated with PTB. Apart from HLA-DR2 association, association of non-HLA genes in the susceptibility to PTB is evident. This suggests that multigenetic factors (candidate genes) may be involved in the susceptibility/resistance to PTB.