Medical Journal of Dr. D.Y. Patil Vidyapeeth

CASE REPORT
Year
: 2014  |  Volume : 7  |  Issue : 2  |  Page : 198--200

Rare cause of pediatric obesity: Bardet - Biedl Syndrome


Mitul B Kalathia, Yogesh N Parikh, Parin N Parmar, Shyamal S Verma 
 Department of Pediatrics, PDU Medical College, Rajkot, Gujarat, India

Correspondence Address:
Mitul B Kalathia
131, Chitrakutdham Society, Kalawad Road, Rajkot - 360 005, Gujarat
India

Abstract

Bardet - Biedl syndrome (BBS) is a rare autosomal recessive disorder, characterized by central obesity, retinal pigmentation, polydactyly, mental retardation, hypogonadism, and renal dysfunction. Other features may include deafness, diabetes mellitus, genitourinary abnormalities, short stature, hormonal abnormalities, developmental defects, and speech problems. We report a case of BBS who presented with night blindness, marked central obesity, polydactyly, syndactyly, hypogonadism, micropenis, and behavioral problems, along with a brief review of the literature.



How to cite this article:
Kalathia MB, Parikh YN, Parmar PN, Verma SS. Rare cause of pediatric obesity: Bardet - Biedl Syndrome.Med J DY Patil Univ 2014;7:198-200


How to cite this URL:
Kalathia MB, Parikh YN, Parmar PN, Verma SS. Rare cause of pediatric obesity: Bardet - Biedl Syndrome. Med J DY Patil Univ [serial online] 2014 [cited 2024 Mar 29 ];7:198-200
Available from: https://journals.lww.com/mjdy/pages/default.aspx/text.asp?2014/7/2/198/126341


Full Text

 Introduction



Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder, characterized by central obesity, retinal pigmentation, polydactyly, mental retardation, hypogonadism, and renal dysfunction. Other features are deafness, diabetes mellitus, genitourinary abnormalities, short stature, hormonal abnormalities, developmental defects, and speech problems. [1],[2]

We report a case of BBS who presented with night blindness, marked central obesity, polydactyly, syndactyly, hypogonadism, micropenis, and behavioral problems, along with a brief review of the literature.

 Case Report



A 12-year-old boy presented to the pediatric outpatient department with the complaint of night blindness. His height and weight were 138 cm (>97 th percentile) [3] and 71 kg (>97 th percentile), [3] respectively, with a resultant body mass index of 41 (>95 th percentile) [3] that indicated severe obesity [Figure 1]. Hexadactyly was present in both lower limbs, along with syndactyly of fifth finger in the left upper limb and malformed fifth finger in the right upper limb [Figure 2] and [Figure 3]. Our patient had low testicular volume of 2 ml (normal 10-12 ml) and micropenis (<2.5 cm) [Figure 4]. Secondary sexual characteristics (pubic hairs, facial hairs, voice change) were absent. School performance of the child was poor, and the child had behavioral problems. Developmental milestones of our case were delayed with an intelligent quotient (IQ) of 75.{Figure 1}{Figure 2}{Figure 3}{Figure 4}

On ophthalmological examination, visual acuity was 6/36 in both eyes. Fundus examination showed pallor and atrophy of the optic disk, with retinal pigmentary changes. Hearing assessment of the child was normal. Investigations such as hemogram, renal function tests, liver function tests, lipid profile, blood glucose, postprandial blood sugar, and urine sugar were normal. An ultrasound revealed normal kidney morphology.

Parents of the child were advised regarding genetic counseling and testing. Child and his parents were advised regarding probable morbidities and were also advised regular follow-up to observe for renal dysfunction, diabetes and its management, if required. Puberty is a particularly stressful time for those with BBS. We referred the patient to a counselor for behavioral problems. There is no proven effective treatment to either prevent or improve the outcome in vision. A low-calorie and low-fat diet was advised to control obesity as per the dietitian's recommendations, and physical exercises were stressed upon.

 Discussion



BBS is relatively rare and less than 20 cases have been reported from India. [4] Beales et al. developed the diagnostic criteria for BBS, according to which presence of four primary features or three primary features and two secondary features is considered for diagnosis of BBS. [2] The primary features include central obesity, retinopathy, polydactyly, mental retardation, hypogonadism, and renal dysfunction, while the secondary features are deafness, diabetes mellitus, genitourinary abnormalities, hormonal abnormalities, short stature, developmental defect, and speech deficits. [1],[2]

Retinopathy occurs in 90% of the patients. Maculopathy associated with disk pallor develops in late childhood. Retinal dysfunction usually becomes apparent at age 7-8 years, when night blindness gradually starts. [2] Macula is involved by second or third decade of life in all individuals, with visual acuity of 20/200 or worse. [5],[6] Other ophthalmological findings include nystagmus, strabismus, high myopia, cataract, and glaucoma. [1],[2]

Postaxial polydactyly is common, but not invariable. [2]

Brachydactyly of the fingers and toes is common. Other findings may include partial syndactyly (most usually between the second and third toes), fifth finger clinodactyly, and a prominent "sandal gap" between the first and second toes. [7]

Obesity is a common feature in almost all the patients. Birth weight is usually normal in individuals with BBS. Significant weight gain begins in infancy and becomes a lifelong issue. The distribution of adipose tissue is more prominent in the trunk and proximal limbs in adulthood. [1],[2],[8] Intellectual disability has been described as a major feature of BBS, but the difficulty of vision while assessing cognitive functions is often ignored. Most individuals have significant learning difficulties and only a minority have severe impairment on IQ testing. [2],[9]

Hypogonadism is more frequent in males than females with BBS. Hypogonadism in females results in failure of development of secondary sexual characteristics and delayed menarche. Males have micropenis at birth, with small-volume testes. Affected females may have malformations of fallopian tubes, uterus, and ovaries. Other complex anomalies of the female genitourinary tract may include complete vaginal atresia, septate vagina, duplex uterus, hematocolpos, persistent urogenital sinus, vesico-vaginal fistula, absent vaginal orifice, and absent urethral orifice. [1],[2]

Progressive renal damage occurs in BBS and can lead to end-stage renal disease necessitating renal replacement therapy or transplantation. [1],[10] Hypertension may occur in 50-66% of the affected individuals. [1],[2]

Speech development is delayed with sentence formation beyond 4 years and various problems in speech is found even in adult patients. [2],[9] Neurological abnormalities in the form of ataxia and impaired coordination are encountered. [2],[8] Psychiatric problems like anxiety, mood disorders, depression, bipolar disorder, obsessive compulsive behavior, and psychosomatic manifestations are observed. [2],[9]

Genes associated with BBS are BBS1, BBS2, ARL6 (BBS3),

BBS4, BBS5, MKKS (BBS6), BBS7, TTC8 (BBS8), BBS9, BBS10, TRIM32 (BBS11), BBS12, MKS1 (BBS13), and CEP290 (BBS14). Molecular genetic testing is available for all these BBS-related genes. [1],[9] Prenatal diagnosis for pregnancies at increased risk for BBS can be done by genetic testing of sample obtained by amniocentesis or chorionic villus sampling. [1],[9]

Prenatal diagnosis using second trimester ultrasound examination in pregnancies at risk to detect anomalies such as postaxial polydactyly and renal cysts found in BBS has been reported. [11] Prenatal appearance of big hyperechoic kidneys with no corticomedullary differentiation should be considered recurrence of BBS. [11] In pregnancies not at increased risk, presence of polydactyly along with the above-mentioned antenatal ultrasound renal anomalies is considered as having BBS syndrome. [11]

References

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10Harnett JD, Green JS, Cramer BC, Johnson G, Chafe L, McManamon P, et al. The spectrum of renal disease in Laurence Moon Biedl syndrome. N Engl J Med 1988;319:615-8.
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