Novel Treatment for Congenital Disorder of Glycosylation in a Patient with Novel Homozygote Mutation of PMM2: A Case Report and Review Literature

Background: In Congenital Disorder of Glycosylation (CDG) type Ia, homozygous mutations of the PMM2 gene cause phosphomannomutase 2 dysfunction. Case presentation: Herein, a 10-month-old girl is presented with severe hypotonia along with inappropriately normal mental status and normal facies. High 2-ketoglutaric acid was detected in her urine; therefore the diagnosis of 2-Ketoglutarate dehydrogenase complex (KDHC) deficiency was made for this patient. High dose of vitamin B1 was administered, because thiamine is considered as a co-factor in this inborn error of metabolism. She responded very well to daily administration of 500 mg/day vitamin B1 and stood up without help 5 months later. She had experienced seizure, which responded well to pyridoxine. Now, she is a 3.5-years-old child, who could talk and walk normally. Recently, whole exome sequencing was performed for her, which showed homozygote mutation of PMM2; therefore the diagnosis was changed from KDHC deficiency to PMM2-CDG. Conclusion: Attention to the pathophysiology of inborn errors of metabolism is necessary, while considering the defective enzymes co-factor may help us to find an option for treatment of such rare diseases.