Genetic alterations that increase the risk of developing leprosy following infection with the bacterium Mycobacterium leprae are reported in a paper published online this week in Nature Genetics.

Leprosy, if left untreated, leads to inflammation of the skin, nerves, eyes and respiratory tract, which can result in severe injuries because of a loss of pain perception. Most people possess a natural, genetic immunity to M. leprae. Eleven genetic variants, mostly in immunity-related genes, are known to contribute to susceptibility to leprosy, but these do not explain all of the genetic risk factors.

Furen Zhang and colleagues conducted a study of 8,313 people with leprosy and 16,017 healthy controls in China. They found six genetic variants, near eight genes associated with increased susceptibility to leprosy. In addition, the authors confirmed all known risk variants. The authors also observed that some of the leprosy risk variants are also known to decrease the risk of certain auto-immune disorders, which may indicate a trade-off between these disorders.