PDSS1 (decaprenyl diphosphate synthase subunit 1) is a heterotetrameric enzyme that catalyzes sequential condensation of farnesyl diphosphate with isopentenyl diphosphate molecules to generate prenyl diphosphates with trans stereochemistry 1. It supplies nona- and decaprenyl diphosphate precursors for ubiquinone-9 and ubiquinone-10 side chains, respectively 1. This function is critical for coenzyme Q10 (CoQ10) biosynthesis and mitochondrial respiratory chain function. Biallelic PDSS1 mutations cause primary CoQ10 deficiency type 2, presenting with diverse clinical phenotypes including infantile multisystemic disease, cerebellar ataxia, encephalomyopathy, and retinitis pigmentosa 23. Intronic variants causing cryptic splicing represent important pathogenic mechanisms 3. CoQ10 therapy effectiveness varies, showing limited benefit in advanced disease stages 4. Beyond its canonical biosynthetic role, PDSS1 regulates oncogenic signaling through a non-enzymatic mechanism. In triple-negative breast cancer, PDSS1 upregulation promotes metastasis via CoQ10-dependent activation of CAMK2A-STAT3 signaling, and catalytic activity is essential for this pathological function 5. Similarly, PDSS1 acts as an oncogene in hepatocellular carcinoma through STAT3 pathway activation 67.