A new genetic syndrome of congenital myasthenia with distinctive ethnic clustering and associated facial malformations transmitted as an autosomal recessive disorder is reported from the Departments of Neurology and Medical Genetics, Chaim Sheba Medical Center, Tel Hashcmer, Sackler School of Medicine, Tel Aviv University, Israel. The syndrome was demonstrated in 14 Jewish patients from ten families of Iraqi or Iranian origin. All patients had bilateral ptosis and predominant facial muscle weakness, 11 had weak masticatory muscles, and 12 had easy fatiguability on prolonged speech. Very mild limb muscle involvement was present in only three cases. The facial malformations included an elongated face, mandibular prognathism with malocclusion and a high arched palate. The course was mild and nonprogressive, the electromyogram showed a decremental response on repetitive stimulation of either the accessory or the facial nerve but myopathic changes were not seen. Antibodies to acetylcholine receptor were absent and all patients had a response to cholinesterase inhibitors and a positive Tensilon test. There was clinical improvement with pyridostigmine. In seven of ten families there was close parental consanguinity. 
COMMENT. The distribution of muscle weakness in congenital myasthenia in these cases is compatible with previous reports where extraocular and facial muscle involvement have predominated . The authors postulated that the facial abnormalities were secondary to the neuromuscular defect. Congenital myasthenia has been described in association with arthrogryposis, the subject of the following article.