Novel compound heterozygous COG5 mutations in a Chinese male patient with severe clinical symptoms and type IIi congenital disorder of glycosylation: A case report

In the current study, one case of COG5-CDG involving a Chinese male patient with severe neurological symptoms, who had previously been misdiagnosed with congenital gyrus malformation, is described. A clinical investigation was performed and targeted next-generation sequencing (NGS) was used to identify COG5 variants in the patient and his family. PCR and Sanger sequencing were performed for the verification of NGS results. The patient showed severe central and peripheral neurological symptoms, while only mild symptoms were reported in a previous reported case, in which different mutations were involved. The reported patient carried the frameshift mutation c.330delT (p.V111Lfs*22), and a missense mutation c.2324 C>T (p.P775L) in the COG5 gene. The c.330delT (p.V111Lfs*22) variant is a novel mutation, while c.2324 C>T (p.P775L) has previously been reported. Inheriting one variant from each of his parents, the current case report furthers the understanding of genotype-phenotype correlations in COG5-CDG.