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Kidney Week

Abstract: PO1596

Atypical Histological Abnormalities in Patients with Nephronophthisis Diagnosed with NPHP1 Deletion

Session Information

Category: Trainee Case Report

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Akira, Maiko, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Suzuki, Hitoshi, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Ikeda, Arisa, Juntendo University Faculty of Medicine, Tokyo, Japan
  • Iwasaki, Masako, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Honda, Daisuke, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Takahara, Hisatsugu, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Tomita, Shigeki, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Rinno, Hisaki, Juntendo University Urayasu Hospital, Urayasu, Japan
  • Suzuki, Yusuke, Juntendo University Faculty of Medicine, Tokyo, Japan
Introduction

Nephronophthisis (NPHP) is a chronic tubular interstitial disorder that exhibits autosomal recessive genetic forms, causing progressive renal failure in children. It is rare to show urinary abnormalities, edema and hypertension in patients with NPHP. Thus, it is often detected only when the renal failure becomes advanced. NPHP is divided into three types leading to the age of end-stage renal failure, i.e., infant type (around five years old), juvenile type (around 13-14 years old), and adolescent type (around 19 years old). In present study, we report a case of NPHP diagnosed at twenty-six years old who was detected renal dysfunction by annual medical check-up.

Case Description

A 26-year-old woman has not been recognized any growth disorder, and has never been pointed out any urinary abnormality in a school checkup. She was detected renal dysfunction (sCr 2.2mg/dL) by annual medical check-up at 26 years old. Urine test indicated low specific gravity urine, but not proteinuria and microscopic hematuria. However, urinary β2-MG was high (805μg/L), and renal biopsy was performed for definitive diagnosis. Histological findings showed no significant findings in glomeruli. However, moderate fibrosis was observed in the interstitial area, and moderate atrophy was observed in the tubules. There was no significant finding in the immunofluorescence analysis, and no electron dense deposits was detected by electron microscopy. Although cyst-like expansion of the tubules was not clear, tubular atrophy was dominantly found in the distal tubules by CK7 staining. Then, we performed genetic analysis of NPHP1 gene, and found complete deficiency of NPHP1 gene, leading to definitive diagnosis of juvenile NPHP.

Discussion


NPHP is often progress to ESRD at an average age of 13-14 years old. Thus, it is exceedingly rare to find NPHP in adult. Although present case did not show the typical histological abnormalities, such as cyst-like expansion of the tubular lesion, we could diagnose by genetic analysis of NPHP1 gene. In patients with renal failure with tubular interstitial disease dominantly in distal tubule, it is necessary to discriminate NPHP even in the adult case.