INTRODUCTION

The term  congenital myasthenic syndromes (CMS) refers to a group of hereditary congentital disorders affecting the neuromuscular junction. Thus, CMS results from a variety of genetic defects associated with neuromuscular transmission. These contrast with the auto-immune causes of myasthenia gravis  and the Lambert-Eaton syndrome. More than a dozen congenital myasthenic syndromes have been classified. Symptoms are usually first evident in early childhood and include drooping eyelids, facial weakness, and limb weakness. Parents of children with congenital myasthenia frequently show no symptoms of the disorder. CMS has been classified according to the recognized site of the defect: presynaptic, postsynaptic or both.