A Malaysian Case of Glycogen Storage Disease Type Vl

Glycogen storage disease (GSD) type VI is one of the rare GSD variants characterised by PYGL mutation. It leads to liver phosphorylase deficiency, thus causing glycogenolysis disorder. Classic manifestations are mild hypoglycaemia, abdominal distension, growth retardation, hepatomegaly, elevated liver transaminases, hyperlipidaemia, and normal lactate and uric acid. This proband is a 14-year-old Malay girl who was the second child of non-consanguineous parents. At four years old, she was referred for the incidental finding of hepatomegaly with deranged liver enzymes. Clinically, there was hepatomegaly (4 cm below the right costal margin) without any growth retardation. Subsequently, at 11 and 13 years old, she experienced a twisted left ovarian cyst and acute colitis, respectively. Biochemically, there was significantly increased transaminases, hypertriglyceridaemia, and mild hypoglycaemia. The liver biopsy result was consistent with GSD. Next-gene sequence analysis test revealed compound heterozygous mutations identified on the PYGL gene: splice site c.772+2_772+3del and missense c.2071G>C (p.Gly691Arg). Biochemical parameters were normalised except for persistent hypertriglyceridemia after treatment with uncooked corn starch four times daily. Family screening of mother and younger brother exhibits both are carriers of a missense mutation at c.2071G>C(p.Gly691Arg). Genetic testing helps patients better understand their conditions and serve as a guide for future pregnancy planning.