Native American myopathy

Native American myopathy (NAM), also known as congenital myopathy type 16 (CMYP16), is a rare inherited muscle disorder that has been primarily described in the Lumbee Native American population of North Carolina, though it has since been identified in other ethnic groups. The condition is caused by mutations in the STAC3 gene, which encodes a protein involved in excitation-contraction coupling in skeletal muscle. This process is essential for muscles to contract properly in response to nerve signals. Native American myopathy typically presents at birth or in early childhood with muscle weakness (myopathy), distinctive facial features including a round face and ptosis (drooping eyelids), short stature, cleft palate or high-arched palate, scoliosis (curvature of the spine), joint contractures, and susceptibility to malignant hyperthermia — a potentially life-threatening reaction to certain anesthetics. Affected individuals may have feeding difficulties in infancy and delayed motor milestones. The skeletal muscle is the primary system affected, though craniofacial and skeletal abnormalities are also prominent features. There is currently no cure for Native American myopathy. Management is supportive and multidisciplinary, focusing on physical therapy, orthopedic interventions for scoliosis and contractures, and careful anesthetic precautions to avoid triggering malignant hyperthermia. Awareness of the malignant hyperthermia susceptibility is critically important for surgical planning. Genetic counseling is recommended for affected families.

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