Gene makes African American more susceptible to TB

A mutated gene found in the immune system significantly increases the risk of developing tuberculosis for African Americans who carry the tuberculosis bacteria, according to a new study.

Researchers from the Baylor College of Medicine and the Methodist Hospital Research Institute published their findings in the open-access journal PLoS One, according to

Every year, tuberculosis kills approximately 1.8 million people worldwide, making it the second deadliest infectious disease worldwide.

Dr. Katherine King, an instructor at the department of pediatrics – infectious diseases at BCM, told that only one in 10 people infected with the tuberculosis bacteria actually end up with tuberculosis.

"We spend a lot of energy screening for tuberculosis and treating the people who test positive," King said, according to "It would be better to know who among those who test positive are most at risk of developing the disease. Then we could focus more attention on that group."

In the study, King and her colleagues determined the genetic sequence of the IRGM1 gene and the area around it for 370 African Americans and 177 caucasians with tuberculosis and compared that data with the data for 180 African Americans and 110 caucasians who did not have tuberculosis.

The scientists found that African Americans with tuberculosis were more likely to have a mutation in the IRGM1 gene, reports. The scientists believe that the mutation can cause an increased risk for developing tuberculosis.

"We still do not know how the protein associated with this gene works in humans," King said, according to "Some studies indicate it might be important in the engulfment of bacteria by macrophages." Macrophages are immune system cells that will engulf and destroy bacteria.

King said studies such as this can improve understanding about immunity to TB and may lead to new treatments.