Clinical and prognostic characteristics of renal hypodysplasia in children: insights from a 10-year single-center cohort.

Renal hypodysplasia (RHD) is a common and severe form of congenital anomalies of the kidney and urinary tract (CAKUT), often leading to chronic kidney disease (CKD) in children. This study, leveraging a 10-year single-center cohort, aims to elucidate clinical and prognostic characteristics as well as genetic causes in pediatric RHD. We enrolled 322 patients diagnosed with primary RHD by ultrasound at Wuhan Children's Hospital in the past decade. Baseline and follow-up data were collected. Kidney outcomes were investigated using Kaplan-Meier curves and Cox regression model to assess risk factors for early CKD event (eGFR < 75 mL/min/1.73 m2). Whole Exome Sequencing and copy number variation analysis were performed to identify genetic causes. Among 322 RHD patients, 281 (87.3%) had unilateral kidney involvement, and 41 (12.7%) had bilateral involvement. Patients with bilateral RHD exhibited worse kidney function and CKD stage (P < 0.001), while unilateral RHD was more frequently associated with additional CAKUT. After median follow-up of 4.5 years, 72 (22.4%) patients reached the early CKD endpoint. Bilateral kidney involvement (HR = 4.40, 95% CI 2.31-8.39, P < 0.001), urine ACR levels (3-30 mg/mmol: HR = 2.24, 95% CI 1.02-4.92, P = 0.044; > 30 mg/mmol: HR = 2.55, 95% CI 1.32-4.93, P = 0.005), and extra-urogenital malformations (HR = 2.28, 95% CI 1.26-4.10, P = 0.006) were independent risk factors. Genetic testing revealed PAX2, WT1 variants, and 17q12 deletion as the most prevalent pathogenic variations. This study reveals distinct clinical and prognostic characteristics between unilateral and bilateral RHD. Bilateral kidney lesions, albuminuria, and extra-urogenital malformations are independent risk factors for kidney function decline. PAX2, WT1 variants, and 17q12 deletion are the most common genetic causes.