CSGALNACT1 encodes chondroitin sulfate N-acetylgalactosaminyltransferase 1, a key glycosyltransferase that catalyzes the transfer of N-acetylgalactosamine (GalNAc) to glucuronic acid residues 1. This enzymatic activity is essential for initiating and elongating chondroitin sulfate (CS) chains, critical components of the extracellular matrix in cartilage and bone 1. CSGALNACT1 plays important roles in chondroitin chain biosynthesis, cartilage formation, and endochondral ossification 1. Beyond skeletal development, CSGALNACT1 regulates CS in perineuronal nets, which modulate synaptic plasticity and axon regeneration; knockout mice demonstrate enhanced spinal cord axon regeneration and altered ocular dominance plasticity 2. CSGALNACT1 is subject to androgen receptor control in prostate cancer, contributing to altered glycosylation patterns associated with cancer progression 3. Clinically, biallelic loss-of-function CSGALNACT1 mutations cause CSGALNACT1-congenital disorder of glycosylation, presenting as mild skeletal dysplasia with advanced bone age, joint laxity, short stature, and facial dysmorphism 14. Recent evidence suggests CSGALNACT1 acts as a proliferation driver and independent prognostic biomarker in papillary thyroid carcinoma 5. Dysregulated CSGALNACT1 expression also occurs in COPD-derived mesenchymal stromal cells, reflecting abnormal extracellular matrix modulation 6.