Given that TB is the main cause of death in HIV-positive people, it was found that those infected with recurrent TB had lower Mtb-specific IgG3 titres; these were preserved in control individuals who did not suffer frequent infection, while the amounts of the other IgG or IgA subclasses were equal in both groups (Fischinger et al. 2021). This evidence concerns the gene IGHG3 and tuberculosis.