genetics of tuberculosis genetics of tuberculosis tuberculosis is a disease caused by the bacterium mycobacterium tuberculosis. the nature of the host-pathogen interaction between humans and m. tuberculosis is considered to have a genetic component. a group of rare disorders called mendelian susceptibility to mycobacterial diseases (msmd) was observed in a subset of individuals with a genetic defect that results in increased susceptibility to mycobacterial infection. genome-wide association studies early case and twin studies have indicated that genetic component are important in host susceptibility to m. tuberculosis. recent genome-wide association studies (gwas) have identified three genetic risk loci, including at positions 3q23, 11p13 and 18q11. as is common in gwas, the variants discovered have moderate effect sizes - but have shown that tb has high polygenic heritability. these studies suggest that while only a handful of alleles have been found, larger well designed studies may find more.