Adult-Onset Nemaline Myopathy

A rapidly progressive type of nemaline myopathy (NM) characterized by a very late onset.

Epidemiology

The annual incidence of NM has been estimated at 1/50,000 live births. Adult-onset NM represents <5% of total cases.

Clinical description

Adult onset NM occurs sporadically between 20 and 50 years of age. It presents with a generalized weakness, myalgia and rapid progression. Several cases have been associated with cardiomyopathy, dropped head syndrome and respiratory involvement. Muscle biopsy can reveal inflammatory changes. Monoclonal gammopathy and paresthesiae may be a marker of poor prognosis.

Genetic counseling

Adult onset NM is usually sporadic and no familial history of neuromuscular diseases is found.