ABSTRACT
Congenital Myasthenic Syndromes [CMS] are characterized by fatigable weakness involving ocular, bulbar, and limb muscle with onset at or shortly after birth. CMS is a group disorders which arise from inherited structural or functional abnormalities of the neuromuscular junction. Diagnosis of CMS is based on clinical and electrophysiological findings. Several genes encoding different proteins express at the neuromuscular junction are currently known to be associated with CMS, these include the gene encoding different subunits of the acetylcholine receptor [CHRNE, EAchR-subunit; CHRNAl: aAchR-subunit; CHRNB1: 13 AchR-subunit; CHRND: oAchR-subunit] the gene encoding the collagenic tail subunit of the acethylcholinesterase [COLQ]; the gene of the choline acetyltransferase [CHAT]; and the gene encoding rapsyn [RAPSN]. A 17-Year-old presented with fluctuating ocular and generalized muscle weakness, ptosis and dysphagia which has begun a few month after birth. At the beginning she had feeding difficulty and recurrent apnea. On examination she has ptosis, external ophthalmoplagia and limb muscle weakness. Her parents are first cousin. Laboratory investigation showed normal creatine phosphokinase [CPK]. EMG revealed nonspecific neuropathic changes. Molecular investigation performing by a collaborative center in Paris has shown a EAchR subunit mutation in the AchR gene. It is the first report of mutation in the Ach receptor gene in an Iranian family. Although rapsyn mutation is a common mutation in Iranian-Jewish population