ART3 (ADP-ribosyltransferase 3) is a mono-ADP-ribosyltransferase with glycosyltransferase activity that localizes to the plasma membrane and extracellular exosomes 1. The gene undergoes complex tissue-specific regulation through alternative splicing and differential promoter usage, with two promoters (palpha and pbeta) showing distinct activation patterns across cell types; notably, heart and skeletal muscle rely exclusively on the pbeta promoter 1. ART3 is expressed in testis specifically on spermatocytes during spermatogenesis 2, and genetic variants in ART3 are associated with non-obstructive azoospermia susceptibility, with protective haplotypes correlating with elevated testosterone levels 3. In cancer biology, ART3 is significantly overexpressed in triple-negative breast cancer (TNBC) and promotes cell proliferation, invasion, and survival through Akt and ERK pathway activation 4. Recent proteomic studies identify ART3 as a disease biomarker with clinical relevance. Plasma ART3 levels are reduced in amyotrophic lateral sclerosis patients and correlate with disease progression 5, while ART3 associations with functional decline and clinical milestones in Duchenne muscular dystrophy suggest prognostic utility 6. Additionally, maternal folate depletion associates with Art3 hypomethylation in adult mouse brain, implicating epigenetic regulation in neurocognitive health 7.