[Clinical characteristics and D-mannose treatment outcomes in 5 patients with MPI-CDG].

Objective: To analyze the clinical characteristics of mannose phosphate isomerase-congenital disorders of glycosylation (MPI-CDG) and evaluated the outcomes following D-mannose treatment. Methods: This case-series study analyzed clinical manifestations, laboratory findings, imaging results, genetic data, and outcomes after D-mannose therapy in 5 children with MPI-CDG diagnosed at the Children's Hospital of Fudan University between December 2014 and December 2024. Results: The age of onset ranged from 0.3 to 0.4 years in all 5 children, who initially presented with diarrhea and hypoglycemia. Associated manifestations included short stature (3 cases), anemia (3 cases), splenomegaly (3 cases), hepatomegaly (4 cases), elevated transaminases (4 cases), and hypoalbuminemia (4 cases). Liver pathology revealed hepatic fibrosis in 3 cases. Genetic testing identified 8 variants in the MPI gene, including 2 novel variants. Following D-mannose treatment, diarrhea and hypoglycemia resolved within 1-2 weeks in all children, with concurrent improvement in anemia. Notably except for Patient 1, who developed progressive splenomegaly, worsening hepatic fibrosis, and portal hypertension despite persistently normal transaminase and albumin levels, the other 4 children showed improvement in transaminase levels, resolution of hypoalbuminemia and amelioration of imaging abnormalities. Conclusions: MPI-CDG typically manifests in infancy with diarrhea and hypoglycemia, often accompanied by multi-system involvement. D-mannose treatment significantly improves metabolic abnormalities and most organ damages. However, close surveillance of liver status is warranted due to the risk of hepatic fibrosis progression in some cases.