Saudi Journal of Kidney Diseases and Transplantation

: 2009  |  Volume : 20  |  Issue : 3  |  Page : 454--457

Bardet-biedl syndrome in a child with chronic kidney disease

Ehsan Valavi1, Mohammad Javad Alemzadeh Ansari2, Ali Ahmadzadeh1,  
1 Department of Nephrology, Abuzar Pediatric Hospital, Jundishapour University of Medical Sciences, Ahvaz, Ahvaz, Iran
2 Medical Student, Faculty of Medicine, Jundishapour University of Medical Sciences, Ahvaz, Iran

Correspondence Address:
Ehsan Valavi
Pediatric Nephrologist, Abuzar Pediatric Hospital, Ahvaz Jundishapur University of Medical Science, Parastar Avenu, Ahvaz


A 4-year old boy was referred for evaluation of renal failure, posterior urethral valve (PUV) and urinary tract infection. His parents added complaints of polyuria, polydipsia, enuresis, shortness of stature, and inappropriate obesity. Serum blood urea nitrogen and creatinine levels were 45 and 3.5 mg/dL, respectively. Urine culture was positive for Pseudomonas aeruginosa, and abdominal ultrasound revealed bilateral small kidneys. The patient«SQ»s history included mild to moderate mental retardation and postaxial polydactyly of both lower limbs amputated two years ago. The combination of mental retar­dation, obesity, postaxial polydactyly, and bilateral renal hypoplasia were compatible with the diagnosis Bardet-Biedl syndrome (BBS). The combination of PUV and BBS is a rare condition that caused this early onset of renal failure and inappropriate obesity guided us to the diagnosis.

How to cite this article:
Valavi E, Alemzadeh Ansari MJ, Ahmadzadeh A. Bardet-biedl syndrome in a child with chronic kidney disease.Saudi J Kidney Dis Transpl 2009;20:454-457

How to cite this URL:
Valavi E, Alemzadeh Ansari MJ, Ahmadzadeh A. Bardet-biedl syndrome in a child with chronic kidney disease. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2022 Jan 19 ];20:454-457
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Full Text


Bardet-Biedl syndrome (BBS) is a rare disorder characterized by mental retardation, obesity, re­tinitis pigmentosa, postaxial polydactyl, short stature, developmental delay, diabetes mellitus, endocrinopathies, speech deficits, hepatic fibro­sis, hearing loss, and renal structural abnorma­lities. [1] Posterior urethral valves are obstructing membranous folds within the lumen of prostatic urethra. They are the most frequent cause of obs­tructive uropathy in boys. [2] We report a case in which we found a rare association of BBS and PUV.

 Case Report

A 4-year-old boy was referred for evaluation of renal failure, posterior urethral valve (PUV) and urinary tract infection. He is the first offspring of first degree cousins. His parents added the com­plaint of polyuria, polydipsia, enuresis, short sta­ture (89 cm, 2 , > 95 percentile), [Figure 1].

Serum blood urea nitrogen and creatinine levels were 45 and 3.5 mg/dL, respectively. Glomerular filtration rate was very low (20.8 mL/min). Other blood chemistries were within normal limits.

A chest X-ray showed decreased bone density especially in proximal homeruns bone, and a wrist X-ray revealed that bone age was compa­tible with two years.

Urinalysis revealed pyuria and microscopic he­maturia, and urine culture was positive for Pseu­domonas aeruginosa.

An abdominal ultrasound revealed bilateral small kidneys (right 59 × 25 mm, and left 54 × 24 mm) with decreased parenchymal thickness, decreased corticomedullary differentiation, and right hydronephrosis.

A voiding cystouretreogram revealed grade IV vesicoureteral reflux on the right urinary tract and grade II on left, trabeculated bladder wall, and mild to moderate dilatation of prostatic u­rethra, which all suggested diagnosis of a PUV, [Figure 2] and [Figure 3]. Diagnosis of PUV was con­firmed with a urethroscopy and then transure­thral resection of the valve's leaflets was per­formed.

Because of inappropriate obesity we reviewed the patient's medical history, which revealed mild to moderate mental retardation and posta­xial polydactyly of both lower limbs which were amputated two years ago. However, ophthalmo­logic evaluation including fundoscopy was un­remarkable.

The combination of mental retardation, obe­sity, postaxial polydactyly, and bilateral renal hypoplasia was compatible with the diagnosis of Bardet-Biedl syndrome (BBS) in addition to the PUV.


BBS was described by Bardet and Biedl in the 1920s. [3],[4] The prevalence of BBS, generally con­sidered a rare disorder, is (1:160000) in Europe. However, its prevalence is markedly increased in highly consanguineous Arab-bedouin communi­ties in the Middle East (1:13500), and in New­foundland, Canada. [5]

The average age at diagnosis is nine years, when visual problems first become apparent, but diagnosis after the age of 50 has also been re­ported. [6] Postaxial polydactyly is present in 69% of patients at birth, but obesity begins to deve­lop around two to three years, and retinal de- generation becomes apparent at a mean age of 8.5 years. [7]

Ocular abnormalities include rod-cone dystro­phy (at the end of the second decade), strabis­mus, retinitis pigmentosa, and cataracts. [8],[9]

Obesity in BBS is encountered in72-96% of the cases. It usually starts in childhood and the severity increases with age. The majority of cases exhibits symptoms within the first year of life. Distribution of adipose tissue is widespread in childhood but in adulthood, become most pro­minent in trunk and proximal limbs. The cause of obesity in these patients is unknown, but ab­normalities of both the pituitary and hypotha­lamus glands have been postulated. [10]

Postaxial polydactyly is a major feature BBS. Moreover, other limb deformities have been re­ported at varying frequencies, brachydactyly of both hands and feet, partial syndactyly, fifth finger clinodactyly, and a prominent gap bet­ween the first and second toes. [7],[10]

Mild to moderate mental retardation is an addi­tional feature of BBS. The frequency of mental retardation and its severity are variable. [11] Appro­ximately 90% of males with BBS suffer from hypogonadism, while complex genitourinary mal­formations may occur in females. [12]

Renal abnormalities have been described in up to 100% of BBS patients, and renal failure is an important cause of morbidity and early mortality. Dysplasia, calyceal and lower urinary tract mal­formations, cystic tubular disease, and defects of tubular concentrating ability have been re­ported. In some cases, this syndrome may result in renal cancers, especially renal cell carci­noma. [10]

Prenatal presentation of BBS with polydactyly and kidney anomalies may resemble that of Meckel syndrome or "Meckel-like" syndrome in the absence of encephalocele. [12]

BBS increases the risk for hypertension, dia­betes mellitus, and congenital heart disease. [8] Generally, the prognosis of patients with BBS is poor. Their survival and quality of life depend on the severity of clinical features, as well as on the quality of the medical care they receive. [14]

Chronic renal failure is rare in children. About one child per year per million population deve­lops end stage renal disease. Anatomical abnor­malities such as obstructive uropathy secondary to PUV, renal dysplasia, reflux nephropathy and cystic kidney disease, account for approximately 35 percent of the cases of chronic renal failure in children. Growth retardation and renal osteo­dystrophy are the most important complications in children with chronic kidney disease, and most of the patients have failure to thrive in mo­derate to severe renal failure. [2],[15],[16]

In our case it seems that the combination of PUV and BBS (a rare association), has caused this early onset of chronic renal failure and an increased body mass index helped us in the diagnosis of this syndrome.


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