Bardet-Biedl syndrome, a rare ciliopathy with a clear UK care pathway.

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive ciliopathy - a genetic condition in which the primary cilium on cells does not work properly. Because cilia are used across many organs, BBS affects the retina, kidneys, hypothalamus, digits and gonads, producing a recognisable multi-system picture.

Diagnosis uses the Beales clinical criteria - four primary features, or three primary plus two secondary features - alongside molecular testing. A BBS gene panel is the usual first genetic test, escalating to whole exome or whole genome sequencing if it is negative. Care is coordinated through the NHS Highly Specialised BBS Service.

Almost all adults with BBS develop significant sight loss from rod-cone dystrophy - typically night blindness in childhood, progressive tunnel vision, and legal blindness by the third or fourth decade. Early low-vision rehabilitation helps preserve independence, and gene therapy trials are underway.

No. The weight gain in BBS is driven by hypothalamic hyperphagia - a powerful, biological hunger signal. Lifestyle work alone rarely controls it. Setmelanotide, an MC4R agonist, is licensed in the UK for BBS-related obesity and produces meaningful weight loss and reduced hunger for many patients.

The kidneys are commonly affected - cystic change, tubulopathy and reduced ability to concentrate urine. A minority of people progress to end-stage renal failure and need dialysis or transplant. Annual monitoring of blood pressure, eGFR and urinalysis catches problems early.

Fertility is often reduced. Males may have micropenis, cryptorchidism and low testosterone; females may have irregular periods, subfertility and Müllerian anomalies. Assisted reproduction is possible, and pre-conception genetic counselling with options such as preimplantation genetic diagnosis is offered through clinical genetics.