[Clinical phenotype analysis of 6 cases of TTC21B gene related nephronophthisis].

Objective: To analyze the clinical characteristics of 6 children with TTC21B-related nephronophthisis to provide reference for early clinical diagnosis. Methods: The general condition, clinical manifestations, laboratory tests and other clinical data of 6 children from 4 families diagnosed with nephronophthisis by genetic testing in Shanghai Children's Hospital from January 2015 to December 2020 were analyzed retrospectively. Results: A total of 6 children (3 males and 3 females) developed proteinuria and progressive renal dysfunction in early infancy. The onset age of proteinuria was 18 (6, 25) months. The age at the onset of renal impairment was 22 (10, 36) months. All 6 children progressed to end-stage renal disease (ESRD) within 10 (4, 65) months of onset. Five children had hypertension, 3 children with abnormal liver function, 2 children with visceral translocation and 1 child with growth retardation. The genetic results suggested that all children carried variations TTC21B gene p.C518R. Conclusions: Children with TTC21B gene p.C518R nephronophthisis had proteinuria and progressed to ESRD at the early stage of life. These nephronophthisis patients commonly presented with liver and renal dysfunction.