Apolipoprotein E polymorphism and clinical course in childhood nephrotic syndrome

Numerous studies have reported on the role of apolipoprotein E (apoE) polymorphism in the progression of diseases associated with lipid abnormalities. However, few studies have been performed to date on the relationship between apoE polymorphism and childhood nephrotic syndrome (NS). In the present study, we evaluated the allelic and genotypic frequencies of the apoE gene and the possible association between the polymorphic forms of the apoE gene on the clinical course in 190 patients with childhood NS, who were further classified into frequent relapsers (FR, 92) and nonrelapsers or infrequent relapsers (IR, 98). Controls included 132 healthy Koreans. Allele-specific primers were used to detect polymorphism of the apoE gene. The allelic frequencies at the apoE locus were 5.9%, 82.6%, and 11.8% for alleles epsilon2, epsilon3, and epsilon4, respectively in the childhood NS group, while those in the control group were 6.8% for epsilon2, 88.3% for epsilon3, and 4.9% for epsilon4. The allelic frequency for epsilon4 in childhood NS was twice that of controls. Moreover, the allelic frequency of the epsilon4 allele in the FR group was 3.4 times that of the control group and 2.5 times that of the IR group. The high frequency of epsilon4 in patients with childhood NS suggests that epsilon4 may serve as a genetic marker for predisposition to childhood NS. We believe that the apoE allele type is of considerable significance in predicting the course of the disease.