EMD

Emery-Dreifuss muscular dystrophy

More than 100 mutations in the EMD gene have been reported in people with Emery-Dreifuss muscular dystrophy. This condition affects skeletal and cardiac muscle, causing joint deformities called contractures, which restrict the movement of certain joints; muscle weakness and wasting that worsen over time; and heart problems, including an increased risk of sudden death.

Almost all of the EMD gene mutations prevent cells from producing any emerin protein. Researchers have not determined how a lack of this protein leads to the skeletal and cardiac muscle abnormalities characteristic of Emery-Dreifuss muscular dystrophy. Studies suggest, however, that an absence of emerin could disrupt the functions of other proteins in the nuclear envelope. These changes may alter the activity of certain genes or weaken the structure of the nucleus, making cells more fragile.

In rare cases, Emery-Dreifuss muscular dystrophy results from EMD mutations that change a single building block (amino acid) in the emerin protein. These mutations lead to the production of an abnormal version of emerin that is unable to interact with other proteins or cannot be correctly inserted into the nuclear envelope. This type of mutation may be responsible for some cases of Emery-Dreifuss muscular dystrophy with unusually mild signs and symptoms.