GFPT1-related congenital myasthenic syndrome misdiagnosed as myopathy: clinical and genetic insights.

Congenital myasthenic syndrome (CMS) is a rare genetic disorder characterized by neuromuscular junction dysfunction, presenting fluctuating muscle weakness. This study presents a 25-year-old male patient of Turkish origin with suspected CMS due to a glutamine-fructose- 6-phosphate transaminase 1 (GFPT1) mutation, along with familial implications involving his mother and uncle. Clinical, electrophysiologic, and genetic assessments were conducted over several years, revealing progressive weakness predominantly affecting proximal limb muscles. Electrophysiologic studies indicated myogenic involvement, with repetitive nerve stimulation demonstrating significant decrements. Whole-exome sequencing revealed a homozygous GFPT1 mutation in both the patient and his mother. Treatment with acetylcholinesterase inhibitors yielded modest improvement. The study underscores the importance of considering CMS in cases of fluctuating weakness, highlighting diagnostic challenges and the role of genetic testing in familial cases. Further research is warranted to elucidate phenotypic correlations and expand understanding of CMS-associated manifestations.