[Analysis of clinical characteristics in 4 pediatric cases of glycogen storage disease type Ⅸa]

Objective: To investigate the clinical manifestations, pathological features, and genetic variant characteristics of children with glycogen storage disease type Ⅸa (GSD Ⅸa). Methods: A retrospective case series analysis was conducted to collected and analyzed the medical history, biochemical markers, liver ultrasound results, liver histopathological findings, genotypes, treatment regimens, and follow-up data of 4 pediatric patients diagnosed with GSD IXa in the Department of Infectious Diseases at Xiamen Children's Hospital from January 2018 to May 2024. All patients were confirmed by genetic testing. Results: All 4 pediatric patients diagnosed with GSD Ⅸa were male. The ages of onset were 8 months, 2 years, 3 years and 3 months, 1 year and 5 months, respectively, with initial presentations including chronic diarrhea (Case 1), incidentally detected transaminase elevation during routine examinations (Cases 2 and 3), and delayed motor development (Case 4). Diagnosis was confirmed at ages 10 months, 3 years, 3 years 4 months and 1 year 6 months, respectively.At diagnosis, anthropometric parameters and biochemical profiles revealed:Height: 68 cm (<P₃), 96 cm (P_25-50), 94 cm (P_3-10), and 94 cm (P_3-10).Weight: 7 kg (<P₃), 17 kg (P_90-97), 14.4 kg (P_25-50), and 10.5 kg (P_25-50).Alanine aminotransferase: 299, 500, 271, and 313 U/L (reference range 0-40 U/L).Aspartate aminotransferase: 285, 543, 337 and 357 U/L (reference range 0-40 U/L).Fasting glucose: 2.80, 3.67, 2.98, and 3.66 mmol/L (reference range 3.90-6.10 mmol/L).Lactate: 4.3, 2.1, 1.3, and 2.6 mmol/L (reference range 0.5-2.2 mmol/L).Triglycerides: 5.22, 1.38, 1.32, and 1.88 mmol/L (reference range 0.56-1.70 mmol/L).Case 1 exhibited poor adherence to uncooked cornstarch therapy during initial treatment, with no significant improvement in biochemical parameters. Follow-up imaging at age 4 revealed hepatic adenoma. Subsequent improvement in therapeutic compliance led to biochemical normalization, reduced hepatic adenoma size, and growth parameters of 113 cm (P_10-25) and 26 kg (P_90-97) at 6 years 2 months. Cases 2-4 demonstrated biochemical improvement with regular uncooked cornstarch therapy and no evidence of hepatic adenoma.Liver histopathology in Cases 1-3 confirmed glycogen accumulation consistent with GSD, without cirrhotic changes. Genetic analysis identified PHKA2 variations in all cases: 2 missense variants, 1 frameshift variant and 1 nonsense variant. The c.2839dup and c.3267G>A variants represent novel pathogenic mutations. Conclusions: GSD Ⅸa in pediatric patients is predominantly characterized by hepatomegaly, hepatic dysfunction, and hypoglycemia. While uncooked cornstarch therapy typically yields favorable prognoses, a subset of patients may develop hepatic adenomas. Notably, children with hepatic adenoma exhibited younger age of onset, significant growth retardation, and more severe metabolic disturbances, suggesting that hepatic adenoma development may be closely linked to the severity of metabolic dysregulation.