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.

Updated clinical and glycomic features of mannosyl-oligosaccharide glucosidase deficiency:Two case reports

BACKGROUND Mannosyl-oligosaccharide glucosidase(MOGS)deficiency is an extremely rare type of congenital disorder of glycosylation(CDG),with only 12 reported cases.Its clinical,genetic,and glycomic features are still expanding.Our aim is to update the novel clinical and glycosylation features of 2 previously reported patients with MOGS-CDG.CASE SUMMARY We collected comprehensive clinical information,and conducted the immunoglobulin G1 glycosylation assay using nano-electrospray ionization source quadruple time-of-flight mass spectrometry.Novel dysmorphic features included an enlarged tongue,forwardly rotated earlobes,a birth mark,overlapped toes,and abnormal fat distribution.Novel imaging findings included pericardial effusion,a deep interarytenoid groove,mild congenital subglottic stenosis,and laryngomalacia.Novel laboratory findings included peripheral leukocytosis with neutrophil predominance,elevated C-reactive protein and creatine kinase,dyslipidemia,coagulopathy,complement 3 and complement 4 deficiencies,decreased proportions of T lymphocytes and natural killer cells,and increased serum interleukin 6.Glycosylation studies showed a significant increase of hypermannosylated glycopeptides(Glc3Man7GlcNAc2/N2H10 and Man5GlcNAc2/N2H5)and hypersialylated glycopeptides.A compensatory glycosylation pathway leading to an increase in Man5GlcNAc2/N2H5 was indicated with the glycosylation profile.CONCLUSION We confirmed abnormal glycomics in 1 patient,expanding the clinical and glycomic spectrum of MOGS-CDG.We also postulated a compensatory glycosylation pathway,leading to a possible serum biomarker for future diagnosis.