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ID NEW FORM OF MD

Researchers at the Mayo Clinic in Rochester, Minn., have identified a previously unknown form of adult-onset muscular dystrophy.

The dystrophy arises from a mutation in a gene called ZASP, located on chromosome 10, and appears to be inherited in an autosomal dominant pattern, meaning a person need inherit only one flawed ZASP gene from either parent to show symptoms. The average age of symptom onset in the patients in this study was 54.

Fifty-four adults with symptoms of muscle disease, such as skeletal muscle weakness and cardiac abnormalities, and a general diagnosis of myofibrillar myopathy (a general category of muscle disease), were tested to see whether their illness was linked to the ZASP gene.

ZASP gene mutations were found in 11 of the 54 patients. Most had weakness in the muscles close to the center of the body (proximal) as well as those furthest away from the center (distal), but distal weakness was greater than proximal weakness in six people. Three people had cardiac abnormalities.

The ZASP protein, for which the ZASP gene carries instructions, is in a part of the muscle cell known as the Z-disk. Z disks separate contracting units of muscle cells from each other deep inside muscle fibers. Many other forms of muscular dystrophy have to do with deficiencies or abnormalities in proteins in the membrane surrounding the fiber.

Neurologist and long-time MDA grantee Andrew Engel, with neurologist Duygu Selcen, announced the findings online Jan. 24 in Annals of Neurology.

Engel has MDA funding for work in myasthenias, another type of muscle disease.