PDE5H

PDE5H is not a widely recognized or standardized gene or protein in major public databases. Within the human phosphodiesterase 5 (PDE5) family, the best-established members are PDE5A and PDE5B, with PDE5A encoding multiple splice variants (such as PDE5A1, PDE5A2, PDE5A3). As of now, there is no universally accepted human gene or protein designated PDE5H in major resources (for example, HGNC, NCBI Gene, or UniProt). When PDE5H appears in some datasets or publications, it is often unclear whether it represents a misannotation, a predicted or unpublished transcript, a species-specific paralog, or an alternate naming for an existing isoform. Consequently, there is no validated functional data, tissue distribution, or clinical relevance that can be assigned to PDE5H.

Background on the PDE5 family: PDE5 enzymes hydrolyze cyclic guanosine monophosphate (cGMP), modulating smooth muscle tone and vascular responses. Pharmacological inhibitors of PDE5, such as sildenafil, tadalafil, and vardenafil, are clinically used to treat erectile dysfunction and pulmonary arterial hypertension by preserving cGMP signaling in target tissues. If PDE5H corresponds to a distinct human protein, its biochemical properties, regulatory mechanisms, and potential roles in physiology or disease would require dedicated experimental validation, including transcript characterization, protein expression, enzymatic assays, and in vivo studies. For authoritative clarification, researchers should consult current genome and protein databases to confirm the correct symbol and associated data.