MDA RESEARCHERS DEVELOP NEW TEST
FOR FORM OF MYOTONIC MUSCULAR DYSTROPHY

TUCSON, Ariz., Feb. 25, 2003 — Molecular biologist Laura Ranum and neurologist John Day at the University of Minnesota in Minneapolis have developed the first accurate genetic test for the type 2 form of myotonic muscular dystrophy (MMD), the Muscular Dystrophy Association announced today.

The researchers, who had MDA support, announced the new test and provided the most thorough description to date of type 2 MMD in today’s issue of Neurology. Ranum and Day first described the disease in 1998.

Day, who directs the MDA clinic at Fairview University Medical Center in Minneapolis, says the new test will likely lead to better and faster diagnosis of MMD 2.

"We're gratified that MDA's investment and the hard work of these investigators has resulted in an accurate diagnostic test for this new form of muscular dystrophy," said Sharon Hesterlee, MDA director of Research Development. "It's very important for patients to have a precise diagnosis, so they can get the right treatments in the future and estimate the risks for generations to come in their families."

The genetic flaw underlying MMD type 2 was first described in 2001 by the Minnesota investigators in collaboration with Kenneth Ricker of Wurzburg, Germany. The flaw is an expanded section of DNA on chromosome 3.

A previously recognized form of MMD, now known as type 1, was identified with MDA support in 1992. It’s caused by an expanded DNA section on chromosome 19.

Both forms of the disease are caused by unstable repetitive sequences in genetic regions that don’t contain instructions for any protein. By studying MMD, scientists hope to learn more about how elongated sections of DNA affect many genes, some a long distance away from the altered section itself.

Type 1 MMD is thought to be the most common adult form of muscular dystrophy, perhaps affecting as many as one in 6,000 people. Type 2 MMD may be as common as type 1 in certain parts of the United States and Europe, Day estimates.

Both MMDs cause gradual loss of muscle function and shrinkage (atrophy) of muscles, with myotonia (inability to relax muscles at will) and nonmuscle effects, such as diabetes, cataracts and cardiac problems.

Type 1 MMD is found in all ethnic groups, but type 2 so far has mainly been found in people of European origin, particularly Germans.

The new test uses a two-step procedure that allows technicians to see large DNA sections previously missed with standard testing. The test has been licensed to Athena Diagnostics of Worcester, Mass. (www.athenadiagnostics.com).

MDA is the nonprofit health agency dedicated to curing muscular dystrophy, ALS and related diseases by funding worldwide research. The Association also provides comprehensive health care and support services, advocacy and education.

For more information about MDA's research and services, call (800) 572-1717 or go to www.mda.org