Syndrome or malformation associated with head and neck malformations Native American myopathy Native American myopathy (NAM) is a neuromuscular disorder characterized by weakness, arthrogryposis, kyphoscoliosis, short stature, cleft palate, ptosis and susceptibility to malignant hyperthermia during anesthesia. orphanet Congenital myopathy - cleft palate - malignant hyperthermia UMLS:C1850625 ICD10:G71.2 MESH:C538343 OMIM:255995 Genetic skeletal muscle disease