Genetic Basis Of Tropical Foot And Leg Lymphedema Identified

Farmers in the highlands of southern Ethiopia scratch out a subsistence living from the region's volcanic red clay. The soil supports the farms, but fine-grained, volcanic rock particles in the dirt threaten the farmers and their families. Continual exposure of bare feet to the volcanic soil causes 1 in 20 people to develop a painful inflammation of the lower extremities that, over time, leads to foot disfigurement. Doctors call it podoconiosis. The locals call it mossy foot. And those affected suffer social stigma as well as debilitating discomfort.

Now, researchers think they know why some 4 million people in at least 10 countries worldwide develop this incapacitating condition. One-fifth carry genetic variants that cause their immune system to react to the volcanic dust. This disease-producing response, triggered by exposure from the lack of shoes, provides a dramatic example of the interaction between genes and the environment.

Writing in the March 29, 2012 New England Journal of Medicine, an international team that includes researchers from the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, describes the genetic link that turns dirt into a toxin.

"This study draws attention to a neglected tropical disease with a devastating impact on poor people and their communities," said NHGRI Scientific Director Dan Kastner, M.D., Ph.D. "It demonstrates the global reach of genomics research into the lives of people in parts of the world where endemic diseases very often go unchecked." ...

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