Congenital disorder of glycosylation caused by mutation of ATP6AP1 gene (c.1036G>A) in a Chinese infant: A case report

BACKGROUND: The ATP6AP1 gene coding for the accessory protein Ac45 of the vacuolar-type adenosine triphosphatases (V-ATPase) is located on chromosome Xq28. Defects in certain subunits or accessory subunits of the V-ATPase can lead to congenital disorders of glycosylation (CDG). CDG is a group of metabolic disorders in which defective protein and lipid glycosylation processes affect multiple tissues and organs. Therefore, the clinical presentation of patients with ATP6AP1-CDG varies widely. In this report, we present a case of ATP6AP1-CDG in a Chinese infant, with clinical features and genotype. CASE SUMMARY: An 8-mo-old boy was admitted to our hospital because unexplained hepatosplenomegaly and elevated transaminases that had been noted while he was being treated for a cough at a local hospital. A post-admission examination at our hospital revealed abnormalities in the infant’s liver, brain, and immune system. Trio-based whole exome gene analysis identified a hemizygous pathogenic mutation c.1036G>A (p.E346K) in exon 9 of the ATP6AP1 gene. This variant of the ATP6AP1 gene has not been reported in East Asian countries until now. CONCLUSION: Based on the infant’s clinical manifestations and the results of genetic detection, he was clearly diagnosed with ATP6AP1-CDG. The clinical manifestations of children with CDG vary widely. Genetic testing analysis helps in the clinical diagnosis of children with CDG.