Beginning in adolescence, which condition is associated with progressive instability, ataxia, and inability to walk?

The condition associated with progressive instability, ataxia, and inability to walk that begins in adolescence is olivopontocerebellar atrophy. This neurodegenerative disorder primarily affects the cerebellum and the brainstem. As it progresses, individuals experience increased difficulty with coordination and balance, leading to ataxia, which is characterized by unsteady and uncoordinated movements.

The onset in adolescence typically indicates a hereditary pattern of the disorder, often linked to genetic factors that result in the degeneration of specific nerve cells in the olivopontocerebellar regions of the brain. This degeneration manifests clinically as instability while walking, loss of fine motor skills, and overall impaired movement control.

Other conditions listed do not share the same pattern of symptoms or onset age. Cystic fibrosis primarily affects the lungs and digestive system, retinitis pigmentosa involves progressive vision loss, and rheumatic fever is an inflammatory disease that can occur as a complication of untreated streptococcal infection and does not lead to ataxia or instability.