ESX1 and tuberculosis: Our study showed that five SNPs [espA(Rv3616c:4055801), espK(Rv3879c:4357597), espE(Rv3864:4340330), espl(Rv3876:4353557) and eccE1(Rv3882c:4362807)] in ESX-1 gene region were associated with clustering which could improve the TB transmission.