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

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.