Neonatal myasthenia gravis. Anti-acetylcholine receptor antibodies in the amniotic fluid.

Neonatal myasthenia gravis (NMG) with mild arthrogryposis was observed at birth in the newborn infant of a myasthenic mother. Anti-acetylcholine receptor (anti-AChR) antibodies were present in the serum of both mother and child, in umbilical cord serum and in the amniotic fluid. The presence of anti-AChR antibodies in the amniotic fluid may be one of the causes of the NMG.