A boy and his mother with lipoprotein glomerulopathy: Two case reports and literature review

Rationale:Lipoprotein glomerulopathy (LPG) is a rare genetic kidney disorder. Here, we report a boy and his mother with LPG.Patient concerns:A 6-year-old boy was admitted to our hospital with a history of 6 months of experiencing foamy urine without apparent cause.Diagnoses:Urinalysis revealed 3+ protein and 2+ occult blood. A 24-hour urinary protein quantification measured 1110 mg. Other laboratory tests revealed that the level of serum albumin was 43.6 g/L, triglycerides 4.31 mmol/L were elevated, and high-density lipoprotein cholesterol 0.71 mmol/L were reduced, whereas total cholesterol and low-density lipoprotein cholesterol levels were normal. Renal biopsy revealed glomerular capillary loop expansion with lipoprotein thrombi on light microscopy, variable-sized vacuoles within the capillary loops on electron microscopy, positive Oil Red O staining, and positive immunofluorescence staining for ApoE. The mother of the patient had a history of uremia 5 years ago. Genetic testing confirmed a deletion of 9 nucleotides (CAAGCTGCG) in exon 4 of the ApoE gene at positions c.480-488 of the boy and his mother, resulting in a deletion of 3 amino acids (Lys143-Arg145del) in the ApoE amino acid sequence at positions 143-145, which was same variant as ApoE Tokyo/Maebashi.Interventions:The boy showed significant improvement after treatment with fenofibrate and telmisartan, with urine protein turning negative after 1 week and blood lipid levels returning to normal after 4 weeks.Outcomes:During 1 year follow-up period, the results of urine routine examination and blood lipid profile remained within normal ranges.Lessons:LPG is a rare and easily misdiagnosed kidney disease with no clinical characteristics. Early diagnosis by kidney biopsy and whole gene test is conducive to early detection and diagnosis, reducing missed diagnosis and misdiagnosis, and improving the long-term prognosis of patients.