A novel mutation in the Glycogen storage disease type III gene

Glycogen storage disease (GSD) III is a rare AR disease. The disease results from deficient glycogen debrancher enzyme activity. The responsible gene (AGL) is located on 1p21. The deficiency of the enzyme leads to accumulation of glycogen in liver and muscles. We report an 18 months year old male toddler who was evaluated for hepatomegaly in our department. His basic biochemical profile showed asymptomatic hepatitis. After we excluded infectious and autoimmune causes we searched for a metabolic disease. We performed a fasting challenge test to evaluate his biochemical response. He developed significant asymptomatic hypoglycemia and acidosis. The clinical findings and the biochemical profile were indicative of a carbohydrates metabolic disease. We performed full AGL gene sequence analysis by PCR of both DNA strands of the entire coding region and the highly conserved exon-intron splice junctions. We found two heterozygous mutations in the AGL gene (c.3929G>A p.W1310X and c.4474C>T p.Q1492X). Both of them have not been described in the literature so far, but create STOP codons. DNA gene sequence analysis by PCR provides an alternative safe and highly reliable method to diagnose GSD III. In addition provides essential information for genetic counseling.