What Your Test Results Mean:

Carriers typically show no symptoms of MEB; however, carriers are at an increased risk of having a child with MEB. Risk for current or future pregnancies is dependent on your partner’s carrier status. Carrier testing of your partner is recommended in addition to consultation with a genetic counselor.

Disease Explained:

Muscle-eye-brain disease is a type of congenital muscular dystrophy characterized by brain malformations and eye abnormalities, muscle weakness, and developmental delay. Individuals with MEB are not able to make the proper chemical modifications to an enzyme called alpha-dystroglycan, which is essential for the development of muscle fibers and neural cells. Without the chemical modifications, alpha-dystroglycan cannot function properly, leading to the symptoms of the disease. There have been mild forms reported in recent years with onset in late childhood and minimal brain involvement. Treatment of individuals with MEB typically includes supportive care.

How the Genetics Works:

Muscle-eye-brain disease is an autosomal recessive muscular dystrophy caused by pathogenic variants the POMGNT1 gene. In general, individuals have two copies of the POMGNT1 gene. Carriers of MEB have a single variant in one copy of the POMGNT1 gene while individuals with POMGNT1-related MEB have variants in both copies of their genes, one inherited from each parent. Risk for two carriers to have a child with the disorder is 25%.