The clinical diagnosis was proposed by Beales and colleagues in the 1999 and it is based on the presence of four primary features or three primary features plus two secondary features. Clinical phenotype is highly variable, ranging from mild and sometimes underdiagnosed forms, to severe phenotypes with multiple organ dysfunction.
Primary diagnostic features
• Retinal degeneration
• Obesity
• Postaxial polydactyly
• Renal anomalies
• Learning disabilities
• Hypogonadism and genitourinary abnormalities
Secondary diagnostic features
• Strabismus, cataracts and astigmatism
• Hypertension/type-II diabetes mellitus
• Metabolic/endocrine abnormalities (subclinical hypothyroidism, polycystic ovary syndrome)
• Brachydactyly/syndactyly
• Anosmia/olfactory dysfunction
• Dental anomalies (small teeth, small lower jaw, short teeth)
• Neurodevelopmental abnormalities (developmental delay, speech delay, epilepsy, behavioural disturbances, ataxia/poor coordination, mild spasticity)
• Liver and other gastrointestinal diseases (Hirschsprung disease, inflammatory bowel disease, celiac disease)
• Cardiovascular and thoraco-abdominal abnormalities
Described BBS features non included in the diagnostic criteria
• Cutaneous dermatoses
• Hearing loss
• Asthma
• Dysregulated immune and hematopoietic systems
• Musculoskeletal abnormalities
BBS1