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.
Visual defects, extra fingers and toes, obesity, learning impairment, reproductive system malformations/infertility and kidney abnormalities are considered the cardinal features. Secondary features include fused/short digits, diabetes mellitus, behavioural abnormalities, poor coordination, absence of smell, abnormalities of mouth/teeth, stomach/intestine, endocrine glands, thorax and abdomen.
Primary diagnostic features
• Retinal degeneration
• Obesity
• Extra fingers and toes
• Renal anomalies
• Learning disabilities
• Reproductive system and genitourinary abnormalities/infertility
Secondary diagnostic features
• Strabismus, cataracts and astigmatism
• Hypertension/type-II diabetes mellitus
• Metabolic/endocrine abnormalities (for example hypothyroidism and polycystic ovary syndrome)
• Fused/short digits
• Absence/reduction of the smell
• Dental anomalies (small teeth, small lower jaw, short teeth)
• Neurologic anomalies (developmental delay, speech delay, epilepsy, behavioral disturbances, poor coordination, mild body rigidity)
• Liver and other gastrointestinal diseases (Hirschsprung disease, inflammatory bowel disease, celiac disease)
• Hearth, thorax and abdomen abnormalities
Other BBS features non included in the diagnostic criteria
• Skin diseases
• Hearing loss
• Asthma
• Immune system dysfunction
• Muscle and skeleton abnormalities
BBS1