Utility of Rapid Exome Sequencing in the Diagnosis of a Rare Congenital Myasthenic Syndromes in a Preterm Infant

Congenital myasthenic syndromes (CMS) are rare and challenging diagnoses in preterm neonates. We presented in this case report a preterm infant with recurrent extubation failures. An exhaustive workup to rule out common etiologies of chronic ventilator dependence was negative including a neostigmine trial, acetylcholine receptor antibodies, and chromosomal microarray. Electromyography (EMG) showed features of a neuromuscular junction defect. After ruling out metabolic, inflammatory, and immune mediated causes, a rapid exome sequencing demonstrated CHRNB1 gene mutation diagnostic of autosomal dominant slow channel CMS. The patient was started on fluoxetine and nebulized salbutamol with a gradual improvement in her respiratory function over time with minimal ventilator support.