Congenital Myopathy Due to RyR1 Gene Mutation in a Newborn Masquerading as a Consequence of Hypoxic-ischemic Encephalopathy

Abstract

Background: Congenital myopathies may be a cause of prolonged and persistent hypotonia and weakness in a newborn, which may be overlooked as a neurological consequence of hypoxic-ischemic encephalopathy. We report such a neonate which turned out to be a case of central core myopathy. Clinical Description: A female neonate born at 38 weeks of gestation suffered birth asphyxia and was referred at 25 days of life due to a persistent need for respiratory support. A review of history revealed that the mother had decreased fetal movements during the third trimester and polyhydramnios. On examination, the baby had a frog-like posture with a paucity of proximal movements with preserved distal movements. Considering the possibility of a congenital myopathy, investigations were carried out. The whole-exome sequencing revealed heterozygous nonsense variation in exon 20 of the RyR1 gene, thus diagnosing the infant as a case of congenital core myopathy. Management and Outcome: The baby was managed with supportive care including ventilatory and nutritional support. Baby remained ventilator dependent, but ultimately succumbed to complications by 2 months of age. Conclusions: A high index of suspicion is required in a newborn with birth asphyxia having unusually persistent hypotonia, thorough clinical examination and appropriate genetic testing can help in identifying an underlying congenital myopathy.

Keywords

• birth asphyxia
• central core myopathy
• floppy infant
• hypotonia