Apolipoprotein E polymorphism and serum concentrations in patients with glycogen storage disease type Ia

In patients with glycogen storage disease type Ia (glucose-6-phosphatase de ficiency), serum triglyceride concentrations are markedly raised, whereas p hospholipids and cholesterol levels are only moderately elevated. In additi on, both VLDL and LDL lipoprotein fractions are raised. Despite these abnor malities, endothelial vascular dysfunction and atherosclerosis seem to be r are in such patients. In view of the crucial role of apolipoprotein E (apoE ) in lipid metabolism, we studied both apoE polymorphism (40 patients) and serum concentration (20 patients) in patients with glycogen storage disease type Ia. The distribution of each allele at the apoE locus was similar to that reported in the general population, whereas serum apoE concentrations were raised in our patients. Raised apoE levels in the serum could play an important role in counterbalancing the at-risk-for-atherosclerosis lipid pr ofile of patients with glycogen storage disease type Ia. Moreover, E3 and E 4 polymorphisms, predominant in our patients, have a high triglyceride bind ing capacity and are thus able to increase triglyceride clearance. However, the origin of raised concentrations of apoE is not completely clear though , bearing in mind previous reports regarding serum protein concentrations i n such patients, increased hepatic synthesis is likely.