Tn-syndrome

• Published in: BBA - Molecular Basis of Disease 1999-10, Vol.1455 (2), p.255-268
• Main Author: Berger, Eric G
• Format: Article
• Language: English
• Subjects: Anemia, Hemolytic - immunology; Antibodies, Monoclonal; Antigens, Neoplasm - chemistry; Antigens, Neoplasm - immunology; Antigens, Tumor-Associated, Carbohydrate - chemistry; Antigens, Tumor-Associated, Carbohydrate - immunology; Azacitidine; Blood Cells - immunology; Erythrocyte Membrane - immunology; Galactosyltransferase; Galactosyltransferases - deficiency; Hematologic Diseases - enzymology; Hematologic Diseases - immunology; Hematologic Diseases - pathology; Humans; Lectins; Leukopenia - immunology; Molecular Structure; Polyagglutinability; Syndrome; Thomsen–Friedenreich antigen; Thrombocytopenia; Thrombocytopenia - immunology
• ISSN: 0925-4439; 0006-3002; 1879-260X
• DOI: 10.1016/S0925-4439(99)00069-1

The idiopathic Tn-syndrome, formerly called ‘permanent mixed-field polyagglutinability’, is a rare hematological disorder characterized by the expression of the Tn-antigen on all blood cell lineages. The immunodominant epitope of the Tn-antigen is terminal α- N-acetylgalactosamine, O-glycosidically linked to protein. Normally this residue is 3′-substituted by β-galactose thereby forming the core 1 structure known as the Thomsen–Friedenreich (TF) antigen (Galβ1⇒3GalNAcα1⇒Thr/Ser). The cause of the exposure of the Tn-antigen appears to be due to the silencing of the gene expression of β1,3galactosyltransferase, since treatment of deficient Tn(+) lymphocyte T clones with 5′azacytidine or Na butyrate leads to reexpression of enzyme activity and the sialylated TF-antigen. The Tn-syndrome is acquired and permanent and affects both sexes at any age. Its origin is unknown. Pluripotent stem cells are affected since all lineages are involved but each one to a variable extent. Therefore, normal cells co-exist with Tn-transformed cells. Clinically, patients suffering from the Tn-syndrome appear healthy. Laboratory findings usually reveal moderate thrombocyto- and leukopenia and some signs of hemolytic anemia not warranting any treatment.