The Novel Apolipoprotein E Mutation ApoE Chengdu (c.518T＞C, p.L173P) in a Chinese Patient with Lipoprotein Glomerulopathy

Abstract

Aims: Lipoprotein glomerulopathy (LPG) is a rare inherited renal disease. Several apolipoprotein E (apoE) mutations have been reported to be related to LPG. Herein, we report a case of a LPG patient with a novel apoE mutation.

Methods: A 45-year-old Chinese female was diagnosed as LPG by renal biopsy. APOE gene was sequenced. Clinical and genetic studies were conducted.

Results: The patient presented with nephrotic syndrome and hypertension. A fasting lipid panel showed mild hyperlipidemia and elevated serum apoE (5.6 mg/dL). Renal biopsy revealed typical LPG lesions with whorled, mesh-like material in dilated glomerular capillary lumens that stained positive for Sudan Ⅲ and apoE. apoE gene analysis revealed a T-to-C point mutation at amino acid 173 that caused a substitution of a proline residue for a leucine residue, which has not been reported previously. We named this mutation apoE Chengdu (c.518T＞C, p.L173P). Two of five of the family members carried this mutation, including the patient's brother who was receiving hemodialysis, and her sister, whose urine protein levels were normal. All mutation carriers were heterozygotes with the apoE genotype ε3/ε3. This mutation was not found among 200 of the local people. Fenofibrate treatment for one year induced clinical improvement.

Conclusions: ApoE Chengdu (p.L173P) is a novel mutation causing LPG. This case supports the hypothesis that the substitution of proline in or near the LDL receptor-binding area contributes to the development of LPG. The detailed mechanism of action of this variant remains to be elucidated.