Early-onset of ADCK4 glomerulopathy with renal failure: a case report.

BACKGROUND: We present a rare early presentation of a ADCK4-related glomerulopathy. This case is of interest as potentially treatable if genetic results are timely obtained. CASE PRESENTATION: We report the case of a 5-year-old boy who was identified with significant proteinuria by a urinary routine screening program for school children. Physical examination revealed dysplastic ears and abnormal folded pinna. Albumin level was 41 g/L (39-53 g/L), and urine proteins/creatinine ratio was 2.6 g/g. Renal ultrasound showed enlarged kidneys and perimedullary hyperechogenicity. Treatment by angiotensin-converting-enzyme inhibitor was not beneficial. Renal biopsy showed signs of focal segmental glomerulosclerosis. After 4 years of follow-up, he developed a clinical nephrotic syndrome and no response to prednisone and other immunosuppressive agents was obtained. Within 6 months, he was in end-stage-renal-failure (ESRF) and hemodialysis was started. He was transplanted at 10 years with his mother's kidney. Genes known to be responsible in steroid-resistant nephrotic syndromes were tested. Our patient is compound heterozygous for two mutations in the aarF domain-containing-kinase 4 (ADCK4) gene. ADCK4 gene is one of the genes involved in coenzyme Q10 (CoQ10) biosynthesis, is located in chromosome 19q13.2 and expressed in podocytes. ADCK4 mutations show a largely renal-limited phenotype. The nephropathy usually presents during adolescence, fast evolves towards ESRF, and may be treatable by CoQ10 supplementation if started early in the disease. Our patient presented nephrotic range proteinuria at 5 years, and he reached ESRF at 10 years. CONCLUSION: ADCK4-related glomerulopathy is an important novel and potentially treatable cause of isolated nephropathy not only in adolescents, but also in children in their first decade of life. Discovery of important proteinuria in an asymptomatic child should prompt early genetic investigations.