Glycogen storage disease-like phenotype with central nervous system involvement in a PGM1-CDG patient
Abstract
OBJECTIVES: A 10-year-old boy presented with cleft palate, hepatopathy, cholecystolithiasis, myopathy, coagulopathy, hyperlipidemia, hypoglycemia, hyperuricemia, short stature, obesity, hypothyroidism, microcephaly and mild intellectual disability. The multi-systemic manifestation involving certain distinct clinical features prompted us to search for a subtype of congenital disorders of glycosylation (CDG).
METHODS: The patient was screened for CDG by examining the distribution of transferrin (TRF) and apolipoprotein C-III (ApoC-III) sialylated isoforms using isoelectric focusing of serum. This was followed by spectrophotometric measurement of phosphoglucomutase 1 (PGM1) activity in fibroblasts and molecular analysis including sequencing and PCR-RFLP of PGM1 gene.
Selected bioinformatics tools were used to evaluate the data. RESULTS: Increased relative levels of di-, mono-and asialotransferrin reflected a defect of N-glycosylation in the patient.
Markedly decreased activity of PGM1 corresponding to less than 5% of control's was found. Sequencing of PGM1 gene revealed the presence of two heterozygous missense mutations c. 1010C>T (p.
T337M) and c. 1508G>A (p.R503Q), whose pathogenicity was confirmed by in silico analysis. CONCLUSION: We report the first Czech patient with a glycosylation disorder due to PGM1 deficiency.
Compared to the described cases, no dilated cardiomyopathy was noted in our patient. However, he suffered from a mild neurological impairment, which is an uncommon feature that extends the phenotype associated with PGM1-CDG.
Lactose-rich diet, which was previously reported to have ameliorated the clinical symptoms in some PGM1-CDG patients, did not result in any improvement in our patient.