Table 1.

Features of Bardet-Biedl Syndrome

FeatureIncidence 1Comment
Major Features Retinal cone-rod dystrophy94%
  • Retinal dystrophy symptoms often bring persons to medical attn, typically in 1st decade of life.
  • Other eye abnormalities (e.g., strabismus, cataracts) can also be present & are considered minor features of BBS.
Central obesity89%
  • Birth weight typically normal
  • Features assoc w/obesity (incl endocrine/metabolic abnormalities & NAFLD) also common & considered minor features of BBS
Postaxial polydactyly79%Brachydactyly &/or syndactyly can be present w/or w/o polydactyly & are considered minor features of BBS.
Cognitive impairment66%Incidence may be ↓ when impairment in vision is taken into consideration (see Major Features, Cognitive impairment).
Hypogonadism & genitourinary abnormalities59%Infertility is common, but both males & females have had biological children.
Kidney disease52%Major cause of morbidity & mortality
Minor Features 2 Neurologic abnormalities
  • DD (81%)
  • Epilepsy (9.6%) 3
  • Behavior/psychiatric abnormalities (35%) 4
  • Ataxia/poor coordination may contribute to gross motor & fine motor delays.
  • Speech abnormalities are common.
Olfactory dysfunction47%-100% 5Incl anosmia & hyposmia
Oral/dental abnormalities~50% 6
Cardiovascular & other thoraco-abdominal abnormalities1.6%-29% 7Incl laterality defects such as situs inversus & situs ambiguous
Gastrointestinal abnormalities
  • Hirschsprung disease (2.8%) 3
  • Inflammatory bowel disease (1.1%) 3
  • Celiac disease (1.5%) 3
  • Liver disease (30%)
"Liver disease" is considered any abnormality on liver imaging &/or abnormal ALT level.
Endocrine/metabolic abnormalitiesMetabolic syndrome (54.3%) 8Presence of metabolic syndrome determined using IDF criteria 9
Subclinical hypothyroidism (19.4%) 8
T2DM (15.8%) 8
Polycystic ovary syndrome (14.7%) 8

ALT = alanine transaminase; DD = developmental delay; IDF = International Diabetes Federation; NAFLD = Nonalcoholic fatty liver disease; T2DM = type 2 diabetes mellitus

1.

Unless otherwise noted, incidence is based on data in meta-analysis of genotype-phenotype associations of 899 individuals with BBS by Niederlova et al [2019].

2.

In addition to those listed under comments of major features

3.

Unpublished data from the Clinical Registry Investigating Bardet-Biedl Syndrome (CRIBBS)

4.
5.
6.
7.
8.
9.

International Diabetes Federation (IDF) criteria for metabolic syndrome:
Central obesity (defined by waist circumference values that are sex and ethnicity specific) PLUS two or more of the following:
• Elevated triglyceride level (>150 mg/dL)
• Reduced high-density lipoprotein level (<40 mg/dL in males and <50 mg/dL in females)
• Hypertension (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥85 mm Hg)
• Elevated fasting plasma glucose OR a diagnosis of T2DM

From: Bardet-Biedl Syndrome Overview

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