What Your Test Results Mean:

Carriers typically show no symptoms of NEB-related NM; however, carriers are at an increased risk of having a child with NEB-related NM. Risk for the current or future pregnancies is dependent on your partner’s carrier status.

Disease Explained:

NEB-related NM is an inherited muscle disorder in which inefficient muscle contraction leads to muscle weakness and the other features of the disease. Individuals with NEB-related NM are not able to properly produce the protein nebulin. Without nebulin, abnormal proteins called nemaline bodies collect in muscle fibers causing inability of skeletal muscles to contract. There are several forms of NM ranging from severe to adult onset. Most individuals with NEB-related NM have a more mild form of NM called typical congenital NM. Symptoms including hypotonia, weakness, and feeding difficulties usually present in the first year of life; however, weakness is typically very slowly progressive and most individuals are able to lead independent, active lives.

Treatment of individuals with NEB-related NM typically includes supportive therapies. Physical therapy to help with muscle weakness as well as speech and or feeding therapies may be beneficial.

How the Genetics Works:

NEB-related NM is the most common type of Nemaline myopathy and is caused by pathogenic variants in the NEB gene. In general, individuals have two copies of the NEB gene. Carriers of NEB-related NM have a single variant in one copy of the NEB gene while individuals with NEB-related NM have variants in both copies of their genes, one inherited from each parent.