engleski

INBORN ERROR OF METABOLISM - RARE CASE OF GLYCOGEN STORAGE DISEASE 9C

Introduction: Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of metabolism, which are due to defects of single genes. Glycogen storage disease type IXC (GSD9C) is a condition caused by the inability to break down a complex sugar called glycogen. It is caused by homozygous and compound heterozygous mutation in the PHKG2 gene. It is inherited in an autosomal recessive pattern and is characterized by onset in childhood of hepatomegaly, hypotonia, growth retardation in childhood, and liver dysfunction. The diagnosis is first suspected from symptoms (hepatomegaly, growth delay) and abnormalities on routine laboratory tests (elevated liver transaminases, cholesterol and triglyceride levels). Specialized enzyme and genetic tests are needed to diagnose GSD9. The treatment is directed toward the specific symptoms that are apparent in each individual. Prolonged fasting should be avoided. Case report: A 5-month old girl infant was admitted to our University Hospital due to persistently elevated liver enzymes. She experienced episodes of mild irritability, but was otherwise asymptomatic. She had mildly enlarged liver and also paroxysmal episodes of hypoglycemia without elevated ketone levels. Plasma amino acids and urinary organic acids were in normal levels, as well as free fatty acids and acylcarnitine profile. Histopathologic evaluation of a liver biopsy revealed glycogen accumulation within hepatocytes. This result refered to GSD. In order to detect the type of GSD, we extracted the DNA and sent it to Blueprint Genetics, a genetic testing company in Helsinki, Finland. Blueprint Genetics performed sequence analysis using the Glycogen Storage Disorder Panel, which identified a heterozygous missense variant c.458A>T, p.(Asp153Val) and a heterozygous frameshift variant c.996_999dup, p. (Asn334Glnfs*56) in PHKG2. Conclusion:Our patient is 1 year and 7 months old now. She is fed with small meals supplemented with uncooked cornstarch. Her blood glucose levels are monitored periodically, as well as during periods of stress. Her liver enzyme levels such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase and gamma glutaryl transferase (GGT) are within normal levels now. She grows normally. Further follow-up will be needed.

glycogen storage disease, inborn errors of metabolism, phkg2 gene

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