BBS Global Day is observed worldwide every September 23 to educate the public about Bardet-Biedl syndrome (BBS), a rare genetic disorder affecting multiple organ systems. The day was established to support affected families and accelerate research into the condition, which is caused by mutations in genes involved in ciliogenesis. BBS, first described by physicians Georges Bardet and Arthur Biedl in the early 20th century, impacts approximately 1 in 250,000 people globally and presents with primary characteristics such as retinal abnormalities, obesity, polydactyly, hypogonadism, renal dysfunction, and learning disabilities. The observance is coordinated by BBS International (Bardet-Biedl Syndrome Foundation) and is supported by family organizations in several countries, including France, Italy, the Netherlands, the United Kingdom, and North America. Activities on this day focus on raising awareness and providing information about the syndrome's symptoms, management, and ongoing research efforts.