Association of vitamin D receptor genotypes with the susceptibility to pulmonary tuberculosis in female patients & resistance in female contacts

To find out whether non-HLA genes such as vitamin D receptor (VDR) and Interleukin-l receptor antagonist (IL-1RA) are associated with the susceptibility or resistance to pulmonary tuberculosis (PTB), genotyping of VDR, and IL-1RA genes was carried out in PTB patients (n=202) and control subjects (n=109). No marked difference in the frequency of the variant VDR genotypes was seen between the PTB patients as a whole and control subjects. However, a significant (P<0.02) increase of VDR genotype tt (mutant homozygotes) was seen in the female PTB patients when compared to female contacts (spouses of male patients). Similarly, a significant (P<0.02) increase of TT genotype (wild type homozygotes) was observed in female contacts compared to female patients. An opposite picture of the VDR genotype frequencies was seen in male patients and male contacts (spouses of female patients). Moreover, an increased frequency of tt genotype was observed in quiescent male patients compared to male relapse patients while no such difference was observed in female quiescent and relapse patients. These differences were not significant. No difference in the genotype frequencies of IL-1RA genes was seen between PTB patients and control subjects. The present study suggested that the genotype tt of vitamin D receptor gene may be associated with susceptibility to pulmonary TB in female patients, and the genotype TT may be associated with resistance in female contacts.