Nephronophthisis (NPHP) is a group of autosomal recessive tubulointerstitial cystic kidney disorders. This article reports a case of NPHP type 12 caused by TTC21B mutations. The girl had an insidious onset, with moderate proteinuria, renal dysfunction, stage 2 hypertension, situs inversus, and short phalanges when she visited the hospital for the first time at the age of 3 years and 6 months. The renal lesions progressed to end-stage renal disease (ESRD) before she was 4 years old. Urine protein electrophoresis showed glomerular proteinuria. There were significant increases in urinary β2-microglobulin and α1-microglobulin. Gene detection revealed two compound heterozygous mutations, c.1552T>C (p.C518R) and c.752T>G (p.M251R), in the TTC21B gene, which came from her father and mother respectively. The c.752T>G mutation was a novel mutation. It is concluded that besides typical tubular changes of NPHP, marked glomerular damage is also observed in patients with TTC21B gene mutations.
肾单位肾痨（NPHP）是一组常染色隐性遗传，主要累及肾小管间质的囊性肾病。该文报道1例TTC21B基因突变所致的NPHP 12型。患儿女，起病隐匿，3岁6个月首次就诊时即存在中量蛋白尿、肾功能损害、高血压2期，并伴有内脏反位、短指/趾，4岁前进展到终末期肾病。尿蛋白电泳以肾小球性蛋白尿为主。尿β2-微球蛋白、尿α1-微球蛋白等肾小管指标均明显增高。基因检测显示TTC21B基因存在c.1552T > C（p.C518R）、c.752T > G（p.M251R）复合杂合突变，前者来自父亲，后者来自母亲。c.752T > G为新发突变。TTC21B基因突变患儿的肾脏病理除了NPHP典型的肾小管改变外，多同时存在显著的肾小球损害。