Cystic Fibrosis and Glycogen Storage Disease: A Case Report of a Rare Association

Background and aims: Glycogen storage diseases (GSD) are inborn error of the glucose and glycogen metabolism resulting from mutations in genes responsible for glycogen synthesis, degradation or regulation. Abnormal glycogen is stored in various tissues, especially liver and muscle. Cystic fibrosis (CF) is caused by the mutations in the CFTR gene. These mutations cause thick and viscous secretions in all exocrine tissues. The co-existence of two inherited liver diseases in the same patient has not been reported before. We reported the first case of cystic fibrosis with glycogen storage disease on a 17 month-old boy.

Methods: Case report

Results: A 17 month-old boy who was diagnosed as cystic fibrosis during neonatal screening (serum immunoreactive trypsinogen was positive. Sweat chloride testing was abnormal (104 mEq/L). CF mutation analysis revealed p.E92K G>A homozygosity. The parents are second degree cousins. He was referred to our hospital due to hepatomegaly and elevated transaminases levels. Since he had massive hepatomegaly and a history of older brother who died of GSD type 3, GSDs were suspected. Laboratory findings were also suggestive for GSD type 3 such as high serum levels of triglycerides and creatine kinase. Liver biopsy was performed and histopathological findings were consistent with GSD. Hepatic glycogen content was high (9 g/100g liver tissue; normal 5-7 g/100g liver tissue).

Conclusion: This is the first report of co-existence of CF and GSD in a child. Cystic fibrosis and GSD are rare inherited diseases and co-existence is unusual. However it may not be surprising in countries where parental consanguinity rate is high.