PDE7A (phosphodiesterase 7A) is a cAMP-specific phosphodiesterase that hydrolyzes the second messenger cAMP, a key regulator of physiological processes 1. PDE7A exists as multiple splice variants with high affinity for cAMP (Km = 0.1 μM) and is expressed in skeletal muscle, heart, B-lymphocytes, and the medial habenula, suggesting roles in muscle signal transduction and neurological function 2. Notably, PDE7A also hydrolyzes the cyclic pyrimidine nucleotide cCMP with higher velocity than cAMP degradation 3. PDE7A expression is upregulated by elevated intracellular cAMP through PKA-dependent mechanisms 4. In disease contexts, PDE7A is overexpressed in triple-negative breast cancer (TNBC) and correlates with poor prognosis; inhibition suppresses TNBC growth by attenuating de novo pyrimidine biosynthesis through downregulation of DHODH 5. Genetically, PDE7A variants are causally associated with increased risk of attention-deficit/hyperactivity disorder and psychiatric disorders through altered cAMP signaling 6. Additionally, PDE7A gene mutations correlate with reduced left habenula volume, implicating PDE7A in depression-related brain structural changes 7. In septic acute kidney injury, reduced PDE7A expression via miR-155-5p upregulation contributes to kidney cell injury 8. These findings identify PDE7A as a multifunctional enzyme with therapeutic potential in cancer, psychiatric, and renal diseases.