A 20-year-old woman from a consanguineous Moroccan marriage, with progressive muscle weakness noted from 2 years of age and evaluated at the University of Bonn, Germany, was found to have congenital myasthenic syndrome (CMS) due to homozygosity of the 1293insG e-acetylcholine receptor subunit mutation. Compared to the original case report of a CMS with end-plate acetylcholine receptor deficiency, heteroallelic for two e-AChR subunit mutations, and affected with mild muscle weakness, in this homozygous case, the weakness was profound and was associated with muscle wasting. [1]
COMMENT. Differences in the acetylcholine receptor mutation haplotype can markedly influence the severity of congenital myasthenic syndrome. This profoundly affected patient is wheel-chair bound, and has almost complete external ophthalmoplegia and progressive kyphoscoliosis. Therapy with 60 to 120 mg of pyridostigmine daily was of limited benefit.