Normolipidemic lipoprotein glomerulopathy with IgA nephropathy - ApoE Kyoto mutation: a case report.

Background: Lipoprotein glomerulopathy (LPG), a rare genetic metabolic kidney disease with poor prognosis, is caused by mutations in the apolipoprotein E (ApoE) gene and is usually accompanied by hyperlipidemia. Lipoprotein glomerulopathy can be complicated by other glomerulopathies, such as membranous nephropathy, lupus nephritis, and immunoglobulin A nephropathy (IgAN), which have been mainly reported in Japan. Herein, we present the first case of a patient with LPG with IgAN from Chongqing, China. In contrast to previous cases, this patient lacked hyperlipidemia and ApoE was a Kyoto mutation.

Case presentation: A 38-year-old man was admitted to our hospital due to proteinuria and hematuria, which was found during urine examination. Renal function and blood lipid and lipoprotein levels were normal. After renal biopsy, the patient was diagnosed of LPG with IgAN. Analysis of the ApoE gene showed a heterozygous C→T transition in exon 3, resulting in a change in the 25th amino acid from arginine to cysteine (Kyoto mutation). Genetic analysis of the family showed that this mutation was inherited from his father and passed on to his daughter. Serum ApoE was 14.4 mg/dL. Combined with the above findings, the patient was diagnosed with LPG accompanied by IgAN. After 18 months of enalapril treatment without lipid-lowering therapy, the patient's renal function and blood lipid levels were stable and urine protein levels were significantly ameliorated.

Conclusion: We presented a rare case of LPG (Kyoto) with IgAN without abnormal blood lipids and other typical clinical manifestations. Therefore, for patients with unremarkable clinical manifestations, renal biopsy is of great value for definite diagnosis of disease.