Congenital Myasthenia Gravis Presenting as Refractory Seizures and Respiratory Failure: A Case Report.

Congenital myasthenia syndrome (CMS) is an inherited disorder that involves muscle weakness and fatigue. It can present at birth or late childhood and has variable presentations and severity. It consists of a heterogeneous group of disorders characterized by defective neuromuscular junction (NMJ) transmission. Muscle weakness is common in patients with CMS, but other clinical presentations depend on the genetic defect. CMS is associated with mutations of genes at NMJ, involving the acetylcholine receptors (AChR) subunits. Here, we present the case of a 14-month-old child who presented with refractory seizures and respiratory depression requiring prolonged ventilation and tracheostomy. His whole exome sequencing (WES) showed a variant in the homozygous state in the CHAT gene. Pathogenic variants in this gene are associated with autosomal recessive presynaptic congenital myasthenic syndrome type 6. He did not have any family history of myasthenia gravis and showed marked improvement after starting pyridostigmine despite being started late. This case report has been accepted for poster presentation at the Oman Genetic Society for Genetic Medicine Scientific Research Day, which was held on the 5th of December 2024.