Case Report: Congenital Myasthenic Syndrome Presenting with Bilateral Vocal Cord Paralysis Caused by De-Novel Compound Heterozygous MUSK Mutation

Abstract

Background: We report the genetic etiology of a case of bilateral vocal cord paralysis in a female infant. Case Description: The female infant developed dyspnea after birth, which improved with treatment, allowing her to be discharged from the local hospital. At 2 months of age, the child experienced a recurrence of dyspnea and was treated in a local hospital with interventions such as tracheal intubation and mechanical ventilation. However, as the child continued to suffer from dyspnea, she was transferred to the neonatal intensive care unit of the Children’s Hospital affiliated to Zhengzhou University for further treatment. A second electronic nasopharyngoscopy examination revealed bilateral vocal cord paralysis. The child underwent a tracheostomy due to a failure to wean from mechanical ventilation; after surgery, the respirator was effectively removed, and oxygen delivery ceased. The child and her parents underwent genetic testing with next-generation sequencing technology, which revealed that the child had two heterozygous variants in the MUSK gene, namely the c.2287G>A heterozygous mutation (p.Ala763Thr) and the c.790C>T heterozygous mutation. In addition, Sanger sequencing was performed, which confirmed that these two mutations were, respectively, inherited from the mother and father. Conclusion: Congenital myasthenic syndrome caused by MUSK gene mutations can present clinically as bilateral vocal cord paralysis in neonates.