One of the mildest form of the glycogenoses. It is characterized by hepatomegaly, growth retardation, elevation of glutamate-pyruvate transaminase and glutamate-oxaloacetate transaminase, hypercholesterolemia, hypertriglyceridemia, and fasting hyperketosis.
Hepatic Phosphorylase Kinase Deficiency; Liver Phosphorylase Kinase Deficiency; Phosphorylase Kinase Deficiency of Liver; Phosphorylase Kinase-Deficient Liver Glycogenosis; Glycogenosis Type VIII.
N.B.: Also classified as GSD Type VIa. GSD Type IX is a variant of the recessive form of defective enzyme without brain involvement.
Fewer than 10 cases have been reported, but it may be underdiagnosed because it is often asymptomatic and, when symptomatic, usually classified as a GSD VI.
X-linked recessive (GSD VIII) and autosomal recessive (GSD IX) types described. Gene map loci are Xp22.2-p22.1 (GSD VIII) and 16q12-q13 (GSD IX).
Deficiency of liver phosphorylase kinase, which is required to activate liver phosphorylase. Protein phosphorylation is a major mechanism of signal transduction.
Clinical finding of hepatomegaly. Enzyme deficiency on liver biopsy.
Massive hepatomegaly in infancy that may regress later in life. Otherwise, children are normal and prognosis is good.
Precautions before anesthesia
Anesthetic management has not been described. If hepatomegaly is significant, functional residual capacity of the lungs may be reduced. Proper preoxygenation would be recommended. Case reports exist where hepatomegaly finally progressed to liver cirrhosis and formation of a hepatocellular adenoma.
No agents specifically contraindicated.
Other condition to be considered
Other glycogen storage diseases described in this section.
MW: Phosphorylase kinase deficient liver glycogenosis: Progression to cirrhosis in infancy associated with PHKG2 mutations (H144Y and L225R). J Med Genet
et al: A female case of type VIII glycogenosis who developed cirrhosis of the liver and hepatocellular tumor. Gastroenterol Jpn