chondroitin-sulfates and Heart-Defects--Congenital

Proteoglycans are a major component of extracellular matrix and contribute to normal embryonic and postnatal development by ensuring tissue stability and signaling functions. We studied five patients with recessive joint dislocations and congenital heart defects, including bicuspid aortic valve (BAV) and aortic root dilatation. We identified linkage to chromosome 11 and detected a mutation (c.830G>A, p.Arg277Gln) in B3GAT3, the gene coding for glucuronosyltransferase-I (GlcAT-I). The enzyme catalyzes an initial step in the synthesis of glycosaminoglycan side chains of proteoglycans. Patients' cells as well as recombinant mutant protein showed reduced glucuronyltransferase activity. Patient fibroblasts demonstrated decreased levels of dermatan sulfate, chondroitin sulfate, and heparan sulfate proteoglycans, indicating that the defect in linker synthesis affected all three lines of O-glycanated proteoglycans. Further studies demonstrated that GlcAT-I resides in the cis and cis-medial Golgi apparatus and is expressed in the affected tissues, i.e., heart, aorta, and bone. The study shows that reduced GlcAT-I activity impairs skeletal as well as heart development and results in variable combinations of heart malformations, including mitral valve prolapse, ventricular septal defect, and bicuspid aortic valve. The described family constitutes a syndrome characterized by heart defects and joint dislocations resulting from altered initiation of proteoglycan synthesis (Larsen-like syndrome, B3GAT3 type).

Topics: Adolescent; Amino Acid Sequence; Aortic Valve; Case-Control Studies; Child; Chondroitin Sulfates; Chromosomes, Human, Pair 11; Consanguinity; Dermatan Sulfate; Electrophoresis, Polyacrylamide Gel; Fibroblasts; Fluorescent Antibody Technique; Glucuronosyltransferase; Heart Defects, Congenital; Heparan Sulfate Proteoglycans; Humans; Immunoblotting; Male; Mitral Valve; Models, Molecular; Molecular Sequence Data; Pedigree; Proteoglycans

Topics: Abnormalities, Multiple; Chondroitin Sulfates; Craniofacial Abnormalities; Enzyme Inhibitors; Farnesyltranstransferase; Genes, ras; Genotype; Germ-Line Mutation; Heart Defects, Congenital; Human Growth Hormone; Humans; Neoplasms; Phenotype; Syndrome

Heparin-induced thrombocytopenia is a rare and serious complication of anticoagulation therapy. There remains a paucity of information pertaining to alternative anticoagulation strategies for use during cardiopulmonary bypass concomitant with heparin-induced thrombocytopenia, especially in children. We report the successful treatment of heparin-induced thrombocytopenia and subsequent hemorrhagic complications postoperatively in a 2-year-old child with Danaparoid (orgaran). Emergent conduit revision with cardiopulmonary bypass was required for a thrombosed systemic-venous to pulmonary-arterial connection (completion modified Fontan procedure). Required doses of Danaparoid were consistently twofold that previously reported for adults.

Topics: Anticoagulants; Cardiopulmonary Bypass; Child, Preschool; Chondroitin Sulfates; Dermatan Sulfate; Drug Combinations; Female; Heart Defects, Congenital; Hemorrhage; Heparin; Heparitin Sulfate; Humans; Thrombocytopenia; Thrombosis