What is the underlying cause of Bardet-Biedl syndrome?

Bardet-Biedl syndrome is primarily caused by defects in cellular cilia. This condition is a ciliopathy, meaning it arises from abnormalities in the structure or function of cilia, which are hair-like projections on the surface of cells that play a critical role in cell signaling and transport. In Bardet-Biedl syndrome, the defective cilia lead to various developmental and physiological issues, including obesity, retinal degeneration, renal abnormalities, and polydactyly, among others.

The genetic basis of Bardet-Biedl syndrome is linked to mutations in several genes (at least 21 identified) that are involved in the formation and maintenance of cilia. These mutations disrupt ciliary function and the signaling pathways that rely on proper cilia structure, resulting in the clinical manifestations seen in the syndrome.

The other options describe different conditions or mechanisms that do not accurately represent the pathophysiology of Bardet-Biedl syndrome. For example, chromosomal deletions and mutations in mitochondrial DNA are not recognized as the fundamental causes of this disorder, nor is autosomal dominant inheritance, as Bardet-Biedl syndrome is typically inherited in an autosomal recessive manner. This highlights the specificity of ciliary dysfunction in the etiology of this syndrome