Leprosy-linked genes identified

Seven genes increase the susceptibility to leprosy, researchers find.

Seven genes increase the susceptibility to leprosy, researchers have found.

Leprosy is a progressive disease that left untreated can damage the skin, eyes and nerves. It is characterized by lesions on the skin, which for centuries made lepers the object of revulsion.

Scientists have long thought that leprosy was only an infectious disease caused by Mycobacterium leprae, and that genetics did not make a difference in the disease.

The mutation findings, published in Wednesday's online issue of the New England Journal of Medicine, run counter to that thinking.

"Though leprosy is not common, the discoveries have significant ramifications for chronic infectious disorders and for host-pathogen interactions in other more prevalent mycobacterial diseases such as tuberculosis," Dr. Edison Liu, executive director of the Genome Institute of Singapore, said in a release.

The researchers analyzed genes from of 706 leprosy patients and 1,225 others with the disease in China to find the seven genes.

The seven genes associated with susceptibility to leprosy are: CCDC122, C13orf31, NOD2, TNFSF15, HLA-DR, RIPK2 and LRRK2.

"A great asset is that the study underpins the genetic data with plausible functional biology experimentation, which is not often seen," said Dr. Tom Ottenhoff, an immunologist at Leiden University Medical Center in The Netherlands, who was not involved in the study.

According to the World Health Organization, 254,525 new cases of leprosy were diagnosed in 2007.

Many people are potentially exposed in regions where leprosy is common, but only a minority become infected and show symptoms, which suggests only some are susceptible to the disease, the researchers said.