Genetic and clinical analysis of Chinese pediatric patients with cystinuria

This study aimed to investigate the genotypic and phenotypic characteristics of Chinese pediatric patients with cystinuria. This was a retrospective study of 14 Chinese pediatric patients with cystine stones. All published studies of the Chinese pediatric cystinuria population were searched and enrolled based on the inclusive standard. Among the 14 pediatric patients with cystinuria, 8 were males and 6 were females. The mean age of first stone onset was 4.0 ± 3.3 years (4 months–9 years). All of the patients had multiple stones, and 57.1% (8/14) had bilateral stones. The mean maximum stone diameter was 1.7 ± 0.6 (range 0.5–2.6) cm. A total of 13 SLC3A1 gene mutations and 9 SLC7A9 gene mutations were detected, of which 41% (9/22) of mutations were novel. Patients with SLC7A9 mutations were more likely to develop bilateral stones than those with SLC3A1 mutations (100% vs. 33.3%, p = 0.03). Thirty-four SLC3A1 gene mutations and twenty-eight SLC7A9 gene mutations were found in a total of fifty-five Chinese children with cystinuria. The SLC7A9 gene mutation distribution was more dispersed, while the SLC3A1 mutation was clustered in exons 6–8. The c.647C > T (p. T216M) (4/53) and c.1113C > A (p. Y371Ter) (4/53) mutations in the SLC3A1 gene and the c.1399 + 2_3insT (3/36) mutation in the SLC7A9 gene represent potential hotspots in cystinuria. Our results present a comprehensive genetic spectrum for pediatric cystinuria patients in China. Patients with SLC7A9 mutations were more likely to develop bilateral stones than those with SLC3A1 mutations. A wide mutation spectrum and the potential mutation hotspots associated with cystinuria were also identified.