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Kidney Week

Abstract: TH-PO472

ADCK4 Nephropathy in Identical Siblings

Session Information

Category: Genetic Diseases of the Kidneys

  • 1202 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Manabe, Shun, Tokyo Rosai Hospital, Ota-ku, Tokyo, Japan
  • Kawashima, Moe, Tokyo Rosai Hospital, Ota-ku, Tokyo, Japan
  • Keiko, Kawachi, Tokyo Rosai Hospital, Ota-ku, Tokyo, Japan
  • Kanai, Koji, Tokyo Rosai Hospital, Ota-ku, Tokyo, Japan
  • Mori, Takayasu, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
  • Taneda, Sekiko, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
  • Moriyama, Takahito, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan
  • Hoshino, Junichi, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan
Introduction

ADCK mutations are recently documented cause of coenzyme Q10 (CoQ10) nephropathy, which emerges during adolescence and progresses to end-stage renal disease in early adulthood. Here, we present the identical twin sisters who were diagnosed with ADCK nephropathy, exhibiting divergent clinical severity.

Case Description

The elder twin displayed proteinuria (0.5 g/day), and kidney biopsy revealed focal segmental glomerulosclerosis (FSGS) during her mid-10s. During initial pregnancy, urinary qualitative tests yielded results ranging from 0 to 2+. During subsequent pregnancy, in late 20s, proteinuria gradually escalated to 3 to 4+. Six months post-delivery, the lab results were as follows: albumin 4.3 g/dL, estimated glomerular filtration rate (eGFR) 126 ml/min/1.73, and urine protein-to-creatinine ratio (UPCR) 3.0 g/gCr. Kidney biopsy demonstrated FSGS (NOS variant) along with mitochondrial accumulation within the podocyte. Despite the initiation of steroid, including pulse steroid therapy, and cyclosporine, proteinuria persisted. Four years later, immunosuppression was discontinued. In late 30s, UPCR increased to 3.6 g/gCr, prompting the reintroduction of steroid, cyclosporine, and rituximab. Although UPCR gradually declined to 1.0 g/gCr, eGFR decreased to 50 ml/min/1.73. Due to steroid-resistant proteinuria, progressive renal dysfunction, pathological findings, and a familial history of FSGS, genetic analysis was conducted, revealing a homozygous pathogenic mutation in ADCK4. Administration of CoQ10 resulted in complete remission of proteinuria (UPCR < 0.3 g/gCr) and restoration of renal function (eGFR 71 ml/min/1.73).
The younger twin also exhibited proteinuria (0.4 g/day), and kidney biopsy demonstrated FSGS during her mid-10s. She had no history of pregnancy, delivery, or comorbidities. At the age of 39, her renal function remained preserved, with an eGFR of 92 ml/min/1.73 and UPCR of 0.23 g/gCr.

Discussion

ADCK4 nephropathy represents a renal-limited subtype of CoQ10 nephropathy, exhibiting a favorable response to CoQ10 supplementation. Therefore, it is crucial to comprehend the clinical characteristics to facilitate genetic testing in appropriate instances. Our case study vividly illustrates a wide spectrum of clinical severity, even in identical twins, thus emphasizing the influence of environmental factors on the exacerbation of ADCK4 nephropathy.