Association of CARD8 Gene Polymorphism and the Development of Extrapulmonary Tuberculosis

Mycobacterium tuberculosis, a species of pathogenic bacteria in the Mycobacteriaceae family, is the infectious agent that causes tuberculosis (TB), one of the most progressive bacterial pathogens in human history. The pathogen is the first cause of mortality linked to a single pathogen worldwide, especially in poor and developing countries. There are two clinical manifestations of disease caused by this bacterium: pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB). A single nucleotide polymorphism (SNP) in the human caspase recruitment domain-containing protein 8 (CARD8) gene of TB infection plays a critical role in the disease progression. Combining this SNP with the CARD8 polymorphism increased the effect, indicating a new link between the CARD8 gene and TB infection. The present study was conducted to determine the association between the polymorphism of the CARD8 gene and EPTB infection in humans. The study included patients (males and females) infected with PTB (n = 50), and EPTB (n = 50), as well as 50 healthy individuals as a control group. Blood samples were collected from all the participants and used to isolate DNA. Using a self-designed nested tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS PCR) assay, the genotypes in CARD8 A/T SNPs were identified. The results showed that there were no significant differences between the types of patients themselves and no significant differences between patients and healthy individuals in the results of ARMS-PCR. The findings of the present study revealed a correlation between patients with EPTB and polymorphisms in CARD8 (rs2043211).