{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n GALNT9, which encodes one member of the UDP‐GalNAc:polypeptide N‑acetylgalactosaminyltransferase family, is involved in the initiation of mucin‐type O‑glycosylation. Notably, GALNT9 belongs to a distinct “Y subfamily” (along with GALNT8, –T17, and –T18) that carries mutations in the conserved UDP–GalNAc–binding motif and therefore displays minimal activity toward classical mucin peptides. This characteristic suggests that GALNT9 may perform specialized or regulatory roles in glycosylation rather than acting merely redundantly with other family members (see."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Expression studies have revealed that GALNT9 is predominantly active in the nervous system. Investigation of human and rodent brain tissues demonstrates that GALNT9 mRNA is largely confined to neuronal populations—including regions such as the cerebral cortex—implying a key role for this enzyme in neuronal O‑glycosylation during brain development and function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In the cancer context, analyses in neuroblastoma have indicated that GALNT9 expression is detected in primary tumor–derived neuroblasts (particularly in substrate–adherent, S–type cell lines) but is absent in metastatic cells. Importantly, patients whose tumors express GALNT9 show significantly improved overall and disease‐free survival, supporting its potential as a prognostic biomarker in this pediatric malignancy."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Additional genomic studies have also implicated GALNT9 as a candidate gene in other contexts. For example, a linkage analysis in families with mitochondrial myopathy and sideroblastic anemia highlighted a chromosomal region containing GALNT9"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": ", and a selection signature analysis in chickens identified a region containing GALNT9 as being associated with variation in abdominal fat deposition."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " These associations underscore the broader biological relevance of GALNT9 beyond the nervous system and suggest that its specialized glycosyltransferase function may contribute to diverse physiological and pathological states.\n "}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In summary, GALNT9 appears to serve as a neural‐specific glycosyltransferase with a potentially unique, regulatory role in initiating O‑glycosylation. Its expression in non‑metastatic neuroblastoma correlates with better clinical outcomes and its genomic variation may be linked to other complex traits. These multifaceted findings warrant further functional studies to elucidate the mechanistic underpinnings of GALNT9 in both health and disease.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Yoshiaki Nakayama, Naosuke Nakamura, Tamiko Kawai, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Identification and expression analysis of zebrafish polypeptide α-N-acetylgalactosaminyltransferase Y-subfamily genes during embryonic development."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Gene Expr Patterns (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.gep.2014.07.001"}], "href": "https://doi.org/10.1016/j.gep.2014.07.001"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "25026003"}], "href": "https://pubmed.ncbi.nlm.nih.gov/25026003"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Xing Li, Jing Wang, Wei Li, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Cloning and expression of a brain-specific putative UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferase gene."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biol Pharm Bull (2005)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1248/bpb.28.429"}], "href": "https://doi.org/10.1248/bpb.28.429"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15744064"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15744064"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "S Toba, M Tenno, M Konishi, et al. 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