CKD in Bardet-Biedl Syndrome: Evidence Supporting Multifactorial Etiology

Introduction: Chronic kidney disease (CKD) is a critical prognostic factor in Bardet-Biedl syndrome (BBS). Early diagnosis and intervention are essential for improving patient outcomes. The present study analyzed kidney function in patients with BBS, with the aim to explore the impact of genetic variants and common risk factors for kidney disease. Methods: A monocentric cross-sectional study was conducted. Patients underwent genetic analysis via next generation sequencing; renal function was assessed and the relationship with the following: (i) age, obesity, hypertension and (ii) genetic mutations was analyzed. Results: A total of 65 patients with BBS were enrolled in the study; renal function was variable, with 25% of patients showing an estimated glomerular filtration rate (eGFR) < 60 ml/min per 1.73 m2. Patients’ age was inversely correlated with the eGFR (P = 0.002). Reduced eGFR significantly correlated with truncating mutations in any BBS gene and hypertension; moreover, multivariate analysis using eGFR as an objective variable and multiple risk factors as explanatory variables, showed that body mass index (BMI) was independently associated with eGFR decline (β = −2.45, P < 0.0001), in addition to age. Interestingly, significant discordance in renal phenotype was revealed in 50% of subgroups of consanguineous or nonconsanguineous patients sharing the same pathogenic variants, indicating clinical variability even in this setting. Conclusion: The present study suggests that BBS is a condition of vulnerability to develop kidney disease, and that age, hypertension and obesity are associated with eGFR decline in adult patients with BBS. Whether effective interventions to treat modifiable factors will reduce CKD risk requires further studies.