Kidney outcomes of coenzyme Q10 supplementation in patients with genetically confirmed CoQ10 nephropathy in Japan.

BACKGROUND

Coenzyme Q10 (CoQ10) nephropathy is a rare mitochondrial kidney disease caused by defects in CoQ10 biosynthesis and represents a unique form of steroid-resistant nephrotic syndrome with a disease-specific therapy. However, data on treatment outcomes of this disease in Japanese patients remain limited.

METHODS

We conducted a retrospective observational study of Japanese patients. Patients with a genetically confirmed diagnosis of CoQ10 nephropathy who received CoQ10 supplementation and had available longitudinal clinical data were included. Changes in the urinary protein-to-creatinine ratio (UPCR) and estimated glomerular filtration rate before and after treatment were evaluated, and adverse events were assessed.

RESULTS

Twelve patients were included in the analysis. The median age at treatment initiation was 9.0 years, and COQ8B was the predominant causative gene (n = 11). One patient harbored a COQ6 variant. CoQ10 supplementation was initiated at a median dose of 10.0 mg/kg/day. The median UPCR decreased from 1.66 g/gCr at baseline to 0.19 g/gCr at 12 months, and 6/7 (86%) patients with available 12-month data achieved a ≥ 50% reduction in proteinuria. Kidney function remained stable, and no patients progressed to end-stage kidney disease during a median follow-up of 28.8 months. Adverse events were mild and did not lead to treatment discontinuation.

CONCLUSIONS

In Japanese patients with CoQ10 nephropathy, CoQ10 supplementation was associated with a substantial reduction in proteinuria and stabilization of kidney function. These findings indicate the importance of early genetic diagnosis and prompt initiation of targeted therapy for this treatable hereditary kidney disease.