Abstract: SA-PO0101
Familial Cystic Kidney Disease Due to a Likely Pathogenic BICC1 Variant: Expanding Clinical Recognition
Session Information
- ADPKD and Cystic Kidney Disease - 3
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1201 Genetic Diseases of the Kidneys: Cystic (Monogenic)
Authors
- Michael, Hany Tobia, Dubai Academic Health Corporation, Dubai, United Arab Emirates
- Alalawi, Fakhriya Juma Abdulla, Dubai Academic Health Corporation, Dubai, United Arab Emirates
- Alhadari, Amna Khalifa, Dubai Academic Health Corporation, Dubai, United Arab Emirates
Introduction
Cystic kidney diseases are a heterogeneous group of disorders with variable clinical, radiologic, and genetic features. While Autosomal Dominant Polycystic Kidney Disease (ADPKD) is most commonly linked to PKD1 and PKD2 mutations, atypical phenotypes associated with non-classical genes are increasingly recognised with expanded genetic testing. Variants in BICC1, a gene implicated in renal development and cystogenesis, though its clinical significance remains incompletely defined.
Case Description
A 42-year-old man with hypertension and preserved renal function (eGFR 96 ml/min/1.73 m2) was evaluated for incidental bilateral renal cysts and intermittent microscopic haematuria. Imaging demonstrated normal-sized kidneys with multiple bilateral cortical renal cysts of varying size and density, including haemorrhagic cysts classified as Bosniak IIF. The largest cyst measures 5.5 × 6 × 6 cm. No extra-renal cysts were identified. Genetic testing using a 243-gene cystic kidney disease panel identified a heterozygous BICC1 variant (c.2016-12C>T), classified as a variant of uncertain significance (VUS). No other pathogenic gene variants were detected. Family screening revealed that the patient’s mother harbored the same gene variant and exhibited bilateral renal cortical cysts with preserved renal function. In contrast, the patient’s brother lacked both the gene variant and any cystic phenotype. This pattern demonstrates co-segregation across two generations, supporting autosomal dominant inheritance with phenotypic concordance.
Discussion
This case highlights an atypical cystic kidney phenotype characterised by preserved renal function, absence of kidney enlargement, and lack of extra-renal manifestations, distinguishing it from classical ADPKD. BICC1 encodes RNA-binding protein involved in ciliary signalling and in regulation of PKD2, supporting its biological plausibility in cystogenesis.
Although currently classified as a VUS, the observed familial co-segregation in this case strengthens the argument for clinical relevance and potential reclassification toward likely pathogenic. Similar reports suggest incomplete penetrance and variable expressivity in BICC1-associated disease.
Differentiating atypical cystic diseases from classical ADPKD is crucial to avoid overestimation of disease severity and inappropriate interventions.