Homocysteine metabolism in endothelial cells of a patient homozygous for cystathionine beta-synthase (CS) deficiency.

Homocysteine Metabolism in Endothelial Cells of a Patient Homozygous for Cystathionine (3-synthase (CS) Deficiency

Homocysteine metabolism.

Homocysteine is a sulfur amino acid whose metabolism stands at the intersection of two pathways: remethylation to methionine, which requires folate and vitamin B12 (or betaine in an alternative reaction); and transsulfuration to cystathionine, which requires pyridoxal-5'-phosphate. The two pathways are coordinated by S-adenosylmethionine, which acts as an allosteric inhibitor of the methylenete...

Cystathionine beta synthase modulates senescence of human endothelial cells

Availability of methionine is known to modulate the rate of aging in model organisms, best illustrated by the observation that dietary methionine restriction extends the lifespan of rodents. However, the underlying mechanisms are incompletely understood. In eukaryotic cells, methionine can be converted to cysteine through the reverse transsulfuration pathway thereby modulating intracellular met...

Severe hyperhomocysteinemia due to cystathionine β-synthase deficiency, and Factor V Leiden mutation in a patient with recurrent venous thrombosis

Homocysteine is an amino acid that is toxic to vascular endothelial cells, and plasma elevations have been associated with venous thromboembolism. Severe hyperhomocysteinemia (>100 μmol/L) may result from mutations in the genes coding for enzymes in the trans-sulfuration or the folate/vitamin B12-dependent re-methylation pathways. Here, we report the case of a young woman with severe, recurrent...

Homocystinuria due to cystathionine beta synthase deficiency.

A two year-old male child presented with cutis marmorata congenita universalis, brittle hair, mild mental retardation, and finger spasms. Biochemical findings include increased levels of homocysteine in the blood-106.62 micromol/L (normal levels: 5.90-16 micromol/L). Biochemical tests such as the silver nitroprusside and nitroprusside tests were positive suggesting homocystinuria. The patient w...