Gene mutation discovered that causes a rare form of Charcot-Marie-Tooth disease

A multi-national research team that includes a Saint Louis University neurologist has discovered a gene mutation that causes a rare form of Charcot-Marie-Tooth disease, an inherited progressive nerve disorder. The findings are published in an advance online issue of Nature Genetics.

Researchers have identified some 50 people from three families who live in St. Louis, Wisconsin, Belgium and Bulgaria and have this form of Charcot-Marie Tooth (CMT) disease, says Florian Thomas, M.D., Ph.D., professor of neurology, molecular virology and molecular microbiology and immunology at Saint Louis University School of Medicine, and associate chief of staff and director of the St. Louis VA Medical Center Spinal Cord Injury/Dysfunction Service.

"The discovery of every new gene advances our knowledge of the function of the organ system for which it is relevant and in which it is expressed," Thomas says. "A gene identified in a specific and rare hereditary disease allows for a better understanding of all similar hereditary diseases.

"Not only that, it also allows for a better understanding of how nerves function in general and in any acquired neuropathy. So finding a gene in a family with CMT can help us understand how neuropathy develops in its most common form, for instance, in this country, that seen in people with diabetes."

CMT is the most common inherited neurological disorder, affecting one in 2,500 people and involving the peripheral nerves, which are the structures that connect the brain and spinal cord to our muscles, skin and internal organs.

Half of those who have CMT have one type of the illness due to a mutation in one particular gene, and the other half have one of many other types of the disease. The form of CMT shared by the three families researchers have studied is known as DI-CMT C. While CMT is rare, neuropathies in general are very common, affecting some 10 million people in this country.

"Finding the gene for this disease leads to new diagnostic possibilities for CMT sufferers," Thomas says.

While three families may not seem like very many, it's enough for scientists to consider offering a commercial test to detect the genetic abnormality to diagnose the type of CMT, Thomas says.

"All of these diseases start out as being found in very few families. But once tests can easily be done, you may find many patients who have the disease," he says.

Thomas, his co-researchers and their affiliated institutions have applied for an international patent for their finding.

"Part of the justification for our international patent application is that identification of the gene can lead to a commercial application -- a gene test."

Thomas, who sees many CMT patients at the St. Louis VA Affairs Medical Center and at Saint Louis University, will present the findings at the April meeting of the American Academy of Neurology in San Diego.

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