[Identification of a mutation in exon 4 of apolipoprotein E gene in a family affected with lipoprotein glomerulopathy].

OBJECTIVE: To identify potential mutation of apolipoprotein E (apoE) gene in a male patient affected with lipoprotein glomerulopathy (LPG), his mother and his sister. METHODS: The patient and his mother both had histologically confirmed LPG. His sister and his father were asymptomatic. Genomic DNA was extracted from peripheral blood samples. PCR products of the coding region of exons 3 and 4 of the apoE gene were cloned into a pTA2 vector and sequenced. Genetic variations of the apoE gene were detected using PCR and restriction fragment length polymorphism (RFLP). RESULTS: An apoE gene mutation was identified in the patient's family. Sequence analysis confirmed a 9-bp deletion in the exon 4 of apoE gene from nt 484 to 492. The 9-bp deletion resulted in loss of 3 amino acids at positions 143-145. The sister of the propositus carried the same mutation, though she had neither proteinuria nor elevated plasma apoE. Sequence analysis of exon 3 showed no abnormality. No abnormalities were found in the father's apoE gene sequence. Analysis of genetic variations of the apoE gene by PCR and RFLP confirmed a 57 bp fragment consistent with the 9-bp deletion in exon 4. The father had a normal ε 3 ε 3 genotype. CONCLUSION: The 9 bp deletion of apoE may be associated with the pathogenesis of LPG.