Objective: To explore the genetic basis for a Chinese patient with congenital disorders of glycosylation-If (CDG-If).
Methods: Whole exome sequencing (WES) was carried out for the patient.
Results: The patient, a 5-year-old girl, has featured severe mental retardation. She had learned to walk at 4 years old and was only able to make sounds like "ma ma" occasionally. She was found to harbor compound heterozygous variants of the MPDU1 gene, namely c.389G>A and c.470T>C, both of which were unreported previously.
Conclusion: Above finding has enriched the mutational spectrum of CDG-If among the Chinese population, with c.218G>A being the commonest mutation, along with a more severe phenotype.