The serum apolipoprotein profile of patients with glucose-6-phosphatase deficiency

Abnormal lipid transport is one of the more severe pathophysiological manifestations of glucose-6-phosphatase deficiency (glycogen storage disease, type I: GSD-I). To characterize further lipoprotein abnormalities in this inborn error of glycogen metabolism, we determined the levels of serum apolipoproteins (Apo) A-I, A-II, B, C-I, C-II, C-III, D, and E in 10 male and 12 female patients, 1-37 yr of age. Results showed that patients with GSD-I have a unique apolipoprotein profile characterized by normal or slightly decreased levels of ApoA-I and ApoA-II, reduced concentrations of ApoD, and significantly increased levels of ApoC-I and ApoC-II (p less than 0.01) and ApoB, ApoC-III, and ApoE (p less than 0.0001) in comparison with age- and sex-matched normolipidemic controls. However, there was some overlap of values in patients and controls for each of the lipid and apolipoprotein constituents with the exception of ApoC-III. This finding supported by the results of the logistic regression analysis showed that the concentration of ApoC-III is the best criterion for distinguishing patients with GSD-I from control subjects and the most characteristic feature of the deranged lipid transport system in this deficiency disease. It remains to be clarified, however, whether the ApoC-III concentrations in patients with GSD-I reflect the degree of other metabolic and clinical manifestations of this disease such as hyperlacticacidemia, hyperuricemia, and growth retardation.