Abstract: Genetic circuits that control transgene expression in response to pre-defined transcriptional cues would enable the development of smart therapeutics. The present disclosure relates to engineered programmable single-transcript RNA sensors in which adenosine deaminases acting on RNA (ADARs) autocatalytically convert trigger hybridization into a translational output. This system amplifies the signal from editing by endogenous ADAR through a positive feedback loop. Amplification is mediated by the expression of a hyperactive, minimal ADAR variant and its recruitment to the edit site via an orthogonal RNA targeting mechanism. This topology confers high dynamic range, low background, minimal off-target effects, and a small genetic footprint. The circuits and systems disclosed herein leverage an ability to detect single nucleotide polymorphisms and modulate translation in response to endogenous transcript levels in mammalian cells.