Genes Discovered Influence Risk of Developing Leprosy

Leprosy, a chronic dermatological and neurological disease, is caused by infection with Mycobacterium leprae, and its manifestation, progression and prognosis are strongly associated with the proficiency of the patient's immune system.

The ability to predict the risk of contracting leprosy can help guide decisions made by public healthcare policymakers when drafting preventative measures for high-risk medical staff working in close contact with leprosy patients.

Scientists at the Genome Institute of Singapore (A*STAR, Singapore) conducted a three-stage genome-wide association studies (GWAS) of leprosy in the Chinese population. The genome-wide discovery analysis (stage 1) involved two independent data sets: a previously published GWAS data set of 706 leprosy cases, 1,225 healthy controls and 4,362 individuals with immune-related diseases as population controls from northern China of Chinese Han descent and a new unpublished data set of 842 leprosy cases and 925 controls from northern and southern China.

The second independent study was genotyped using Human 660K-Quad BeadChips (Illumina; San Diego, CA, USA). The scientists discovered six new susceptibility loci, and further gene prioritization analysis of these loci implicated Basic Leucine Zipper Transcription Factor, ATF-Like 3 (BATF3), Coiled-Coil Domain Containing 88B (CCDC88B) and Class II, major histocompatibility complex, transactivator-Suppressor of cytokine signaling 1 (CIITA-SOCS1) as new susceptibility genes for leprosy. They found the same genes linked to leprosy susceptibility also affect the level of aggression expressed by the immune system observed in autoimmune and inflammatory diseases. A person with an overly-aggressive immune system may have a good defense against infection, but stands a higher risk of developing autoimmune diseases where one's own white blood cells attack healthy cells that can lead to death in severe cases.

Jianjun Liu, PhD, a professor and lead author of the study, said, “Although commonly viewed as a medieval affliction, leprosy remains a major health problem in developing countries, claiming over 200,000 new patients worldwide annually with two to three million people permanently disabled. With the discovery of more gene variants that affect the risk of developing leprosy, we can develop better diagnostic, treatment and preventive strategies to one day eradicate leprosy permanently.” The study was published online on February 3, 2015, in the journal Nature Genetics.

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Genome Institute of Singapore
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