Abstract
Nephronophthisis (NPHP) is one of the renal ciliopathies and is also a cystic renal
disorder with an autosomal recessive inheritance, which usually progresses to end-stage
renal disease (ESRD). It affects children, adolescents, and young adults. In approximately
15% of cases, the features of a ciliopathy syndrome, which include liver fibrosis,
skeletal anomalies, retinal abnormalities, and neurodevelopmental delay, will be present.
We describe a case of a 2-year-old male child with ESRD on hemodialysis and a family
record of a similar condition (his brother). The clinical features of this child are
succinctly summarized. The genetic study was conducted using whole exome sequencing.
TTC21B mutational variants were detected in our patient who exhibited nephrotic-range proteinuria,
focal segmental glomerulosclerosis, and tubulointerstitial lesions that evolved to
ESRD. Compound heterozygous mutations, c.626c > t (p.P209L) in exon 6 and c.450 g > a
(p.W150Ter) in exon 5, were uncovered. These findings are in line with the description
of autosomal recessive NPHP type 12. Both clinical and pathological diagnoses of NPHP
are critical, bearing in mind ESRD as well as its related extrarenal defining features.
Identification of the pathogenic variants in the TTC21B gene assisted in the successful proof of the clinical diagnosis NPHP12 as well as
providing information for formal suitable prenatal counseling.
Keywords
ciliopathy - ESRD - nephronophthisis -
TTC21B
- whole exome sequencing
