Objectives: We aimed to perform genetic testing and clinical data of patients with Congenital Myasthenic Syndrome, a rare disorder caused by mutations in genes encoding molecules expressed in the neuromuscular junction and constitutes fatigable muscle weakness.
Materials & methods: Sixteen patients were screened in Taban Clinic, Tehran, Iran from 2014 to 2015 for the hot spot mutations in known CMSs genes (CHRNE, CHAT, RAPSN) based on clinical data. PCR was performed and then direct DNA sequencing was done for mutation identification.
Results: Most patients represented the criteria of Congenital Myasthenic Syndrome in view of early ptosis, motor delay, normal mental development, easy fatigability, decrement in repetitive nerve stimulation test of EMG-NCV and a negative result for antibody against of acetylcholine receptor. No variations were found in the mutational analysis of the CHRNE gene. Analysis of CHAT gene revealed c.358G>A (P. A120T) variation in 9 patients. In the gene RAPSN, polymorphism c.456T>C )P.Y152Y) and polymorphism c.193-15C>T (IVS1-15C>T) were identified in 11 and one patients, respectively.
Conclusion: The common founder mutations of involved genes in CMSs could be very rare among ethnic Iranian. Screening of the entire genes would be efficient to distinguish the specific mutations in specific ethnicity.
Keywords: CHAT; CHRNE; Congenital myasthenic syndrome; Hot spot mutation; Rapsyn.