Kidney Cysts in Children with Alport Syndrome: a Report of Three Cases

Alport syndrome (AS) is a progressive hereditary kidney disease characterized by hematuria, proteinuria, and progressive kidney dysfunction accompanied by sensorineural hearing loss and ocular abnormalities. Pathogenic COL4A3-5 variants can result in different AS spectra. Further, kidney cysts have been reported in adults with AS. However, the relationship between kidney cysts and AS remains unclear. Herein, we report three cases of AS in children that occurred with kidney cysts. The patient in case 1 was initially diagnosed with IgA nephropathy at age 8 but later developed bilateral multiple kidney cysts at age 17, suggesting autosomal dominant polycystic kidney disease. Whole-exome sequencing identified a pathogenic COLA4A5 variant and confirmed the AS diagnosis. The patients in cases 2 and 3 had already been diagnosed with X-linked AS using kidney biopsy and genetic analysis. Initial kidney ultrasonography showed nephromegaly; however, kidney cyst formation was observed during their annual follow-up. Our study supports the association between AS and kidney cysts. Kidney cysts in adolescents with suspected AS should not discourage clinicians from testing for pathogenic COL4A3–COL4A5 variants. Early detection of kidney cyst is critical because it may indicate kidney disease progression.