Early studies on patients with vascular disease described elevated Hcy concentrations after methionine loading and decreased CBS activity, resembling heterozygotes for CBS deficiency.
The molecular basis of cystathionine beta-synthase deficiency in Dutch patients with homocystinuria: effect of CBS genotype on biochemical and clinical phenotype and on response to treatment.
To test this possibility, we studied cDNA derived from four well characterized patients with POAD, exhibiting hyperhomocysteinemia and reduced CBS activities, from four normal controls, and from four obligatory heterozygotes for CBS deficiency.
In order to clarify whether cystathionine beta-synthase (CBS) could differentiate groups of patients with various vascular diagnosis, CBS was studied in cultured human skin fibroblasts from 99 human subjects diagnosed as homozygotes or heterozygotes for CBS deficiency or suffering from atherosclerotic vascular disease or Down's syndrome (prone to less atherosclerosis).