An infant with multiple deformations born to a myasthenic mother.

An infant with multiple deformations born to a mother with untreated myasthenia gravis presented with arthrogryposis multiplex, craniofacial dysmorphism, kyphoscoliosis of the thoraco-lumbar spine, severe hypotonia, absence of the sucking reflex, and other neurological deficits. The neurological state of the infant supported the diagnosis of congenital myasthenia gravis, but the negative Tensilon test and the lack of clinical improvement after prolonged Mestinon treatment ruled out this diagnosis. We believe that the multiple deformations and reduced fetal movements are related to the maternal myasthenic environment associated with mild polyhydramnion.