Recent findings in genetic research have suggested that a large number of genetic disorders that were not previously identified in the medical literature as associated, may, in fact, be highly related through the primary cilia. Cilia are small, hair-like appendages attached to the surface of human cells. They act like antennae, sensing and evaluating extracellular signals to coordinate the development and stability of a wide variety of organs. Ciliopathies are a newly emerging group of genetic diseases caused by defects in the function or structure of cellular primary cilia. These diseases present with symptoms such as mental retardation, retinal blindness, obesity, polycystic kidney disease, liver fibrosis, ataxia and some forms of cancer. Thus, BBS is a ciliopathy; a rare, multi-tissue disorder linked to mutations in 14 different proteins. The pleiotropic phenotype is due to dysfunction of basal bodies and cilia [9, 10].
The variable manifestations of BBS were initially described by Bardet and Biedl in the 1920s . Renal dysfunction has been recognized only recently to be a component of the BBS clinical phenotype. Renal malformations in BBS had been reported infrequently, although a high frequency of structural abnormalities were observed post-mortem. In one study, 26 of 57 patients (46%) had renal structural abnormalities. However, only 5% had functional impairment at the time of assessment [7, 11].
Somwanshi reported on four cases (three males, one female) with polydactyly, hypogonadism, retinitis pigmentosa, obesity, and mental retardation; however, renal function was normal in all of these cases . Pal and Bhattacharyya described an 18-year-old woman with pigmentary retinopathy, hypogenitalism, dwarfism, polydactyly, obesity, and mental retardation, but without renal involvement . Cysts in the left kidney were detected in a 30-year-old patient; her renal function, however, was normal . Gupta  reported a 20-year-old woman with renal insufficiency and multiple fractures, possibly related to renal osteodystrophy; her serum creatinine level was 3.0 mg/dL and ultrasonography revealed bilateral hypoplastic kidneys. Rathi described the first case from India with ESRD who was treated with continuous ambulatory peritoneal dialysis . Hooda et al. described the case of a 12-year-old boy diagnosed as having BBS with stage III chronic kidney disease that progressed to ESRD with consistent creatinine of approximately 11 mg/dL and calculated glomerular filtration rate of 5.68 mL/minute. He underwent successful renal transplantation .
The frequency of renal involvement reported in BBS varies. A questionnaire-based evaluation  reported anatomic anomalies, renal insufficiency, and ESRD, with abnormalities including renal cysts, fetal lobulation, scarring, dysplasia, unilateral agenesis, ectopia, vesico-ureteric reflux, and calyceal clubbing or blunting. Renal insufficiency is noted in approximately 5% to 25% of patients with BBS, progressing to ESRD in 4% to 10%. Renal failure is the commonest cause of death in BBS [16–18]. Renal histology has revealed chronic interstitial nephritis, mesangial proliferative glomerulopathy, and ultrastructural changes in the glomerular basement membrane [19, 20]. Most cases of BBS are diagnosed after the first decade of life and diagnosis in early childhood is very rare unless there is a family history [7, 10].
Our patient's case was particularly interesting in that he presented with ESRD at an earlier age than the most other reported cases. The delay of diagnosis in the context of consanguinity of the parents and the existence of similar cases in the family is surprising, but could be explained by the reluctance of this family to provide sufficient data to the doctors regarding the other affected members. Also, ultrasonography during pregnancy is not compulsory in Romania and this could explain why the patient's kidneys were not assessed before birth. Even after birth, no connection was made between the hexadactily and a possible genetic disorder.
Although the BBS/ALMS APEX array improves the mutation detection possibilities of first-line mutation screening, it is clear that some mutations that contribute to these diseases remain unknown, mainly in less studied populations. It is essential that future research endeavors determine the prevalent mutations in such populations, followed by inclusion of newly identified mutations on the BBS/ALMS1 APEX chip (or other diagnostic tests), so that appropriate genetic diagnosis, counseling, and understanding of the pathogenesis and outcomes of these diseases can be achieved in all ethnic groups.
The management of renal failure in BBS does not differ from that due to any other cause and all three modalities of long-term renal replacement therapy (RRT), that is, hemodialysis, chronic peritoneal dialysis, and renal transplantation can be offered to these individuals. Nonetheless, it represents a very rare indication for kidney transplantation.