Bardet-Biedl syndrome (BBS) is a rare genetic disease1

A daughter and mother are walking outdoors arm-in-arm. The daughter, wearing a black cardigan and sunglasses, is holding a cane, while the mother is in a gray sweater and smiling.

BBS is a rare autosomal recessive ciliopathy affecting about 1 in 140,000-160,000 individuals in Canada.2,3 It is more prevalent in Newfoundland and Labrador, where it affects about 1 in 17,000 people.3

As a multisystemic disorder that is caused by ciliary dysfunction, BBS has highly variable clinical manifestations.4

Hallmark clinical features Additional clinical features1,10
Obesity (72%-92%)5-7

  • Typically early onset by age 5
  • Speech delay
  • Developmental delay
  • Diabetes mellitus
  • Congenital heart disease
  • Dental anomalies
  • Brachydactyly/syndactyly
  • Ataxia/poor coordination
  • Anosmia/hyposmia
Hyperphagia (insatiable hunger)8

  • Preoccupation with food
  • Excessive food-seeking behaviour
  • Presents before the age of 5
Visual impairment (93%)1,5 

  • Onset of rod-cone dystrophy presenting as atypical retinitis pigmentosa, usually between 5 and 10 years of age
Renal anomalies (53%)1,5,9

  • Generally involves cystic tubular disease and anatomical malformations
  • Renal disease is often detectable before the age of 10, and in some cases before age 1
Cognitive impairment (>50%)5
Postaxial polydactyly (63%-81%)5
Hypogonadism (59%-98%)1

 

 

BBS has a highly variable phenotype with common features that evolve over time1,11,12
Birth First years of life
(0-5 years)		 Early childhood
(>5 years)
Postaxial polydactyly1,10,13-15
(63%-81%)		 Extra digits (postaxial) Typically surgically removed
Renal anomalies1,10,16
(53%)		 Anatomical malformations Progressive kidney disease Polyuria/polydipsia
Obesity1,7,8
(72%-92%)		 Normal birth weight Rapid weight gain 
Unusual food seeking Severe obesity 
Behaviours persist
Cognitive impairment1,4
(>50%)		 Developmental delay Learning difficulties
Visual impairment1,17
(93%)		 Progressive vision loss
Night blindness

References:

1. Forsythe E, Beales PL. Eur J Hum Genet. 2013;21(1):8-13. 2. Vaisse C et al. Cold Spring Harb Perspect Biol. 2017;9(7):a028217. 3. Bardet-Biedl Syndrome. Fighting Blindness Canada. Accessed March 31, 2023. https://www.fightingblindness.ca/eyehealth/eye-diseases/bardet-biedl-syndrome/. 4. Beales PL et al. J Med Genet. 1999;36(6):437-446. 5. Forsythe E et al. Front Pediatr. 2018. doi:10.3389/fped.2018.00023. 6. Pigeyre M et al. Clin Sci (Lond). 2016;130(12):943-986.7. Pomeroy J et al. Pediatr Obes. 2021;16(2):e12703. 8. Sherafat-Kazemzadeh R et al. PediatrObes. 2013;8(5):e64-e67. 9. Forsythe E et al. J Am Soc Nephrol. 2017;28(3):963-970. 10. Forsyth R, Gunay-Aygun M. GeneReviews®. July 14, 2003. Updated July 23, 2020. Accessed May 3, 2022. https://www.ncbi.nlm.nih.gov/books/NBK1363. 11. Castro-Sanchez S et al. J Med Genet. 2015;52(8):503-513. 12. Katsanis N et al. Hum Mol Genet. 2001;10(20):2293-2299. 13. Khan OA et al. Cureus. 2019;11(2):e4114. 14. Agrawal H et al. Pediatr Rev. 2018;39(5):e21-e23. 15. Vlahovic AM, Haxhija EQ. Pediatric and Adolescent Plastic Surgery for the Clinician. Springer; 2017:89-105. 16. Putoux A et al. Pediatr Nephrol. 2012;27(1):7-15. 17. Weihbrecht K et al. Med Res Arch. 2017. doi:10.18103/mra.v5i9.1526.