title: Cystathionine beta synthase: gene dosage effect in trisomy 21.
abstract: The enzymatic activity of cystathionine beta synthase has been studied in fibroblasts of nine patients with regular trisomy 21. An excess of CBS activity was found in trisomy 21 with a trisomy 21/normal ratio equal to 1.66. A 1.04 ratio was found in 21q21----21 p ter monosomy; a 1.04 and 0.99 ratio was found in two 21 qter----21q22.3 monosomies; a 1.14 ratio in 21 qter----21q22 monosomy; a 0.89 ratio in a 21q21----21 pter trisomy; an excess of CBS activity was found in a 21q22.1 ----21q21 trisomy with a 1.57 ratio. These results show a gene dosage effect in human fibroblasts trisomic for chromosome 21 and suggest the assignment of human CBS locus between 21q22.1 and 21q21.
authors.forename: B
authors.initials: B
authors.lastname: Chadefaux
authors.forename: M O
authors.initials: MO
authors.lastname: Rethoré
authors.forename: O
authors.initials: O
authors.lastname: Raoul
authors.forename: I
authors.initials: I
authors.lastname: Ceballos
authors.forename: M
authors.initials: M
authors.lastname: Poissonnier
authors.forename: S
authors.initials: S
authors.lastname: Gilgenkranz
authors.forename: D
authors.initials: D
authors.lastname: Allard
mesh_terms: D000293:Adolescent; D002478:Cells, Cultured; D002871:Chromosome Banding; D002904:Chromosomes, Human, 21-22 and Y; D003541:Cystathionine beta-Synthase / Q000235:genetics*; D004303:Dosage Compensation, Genetic; D004314:Down Syndrome / Q000201:enzymology* / Q000235:genetics; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D006836:Hydro-Lyases / Q000235:genetics*; D007223:Infant; D008297:Male
chemical_list: D006836:Hydro-Lyases; D003541:Cystathionine beta-Synthase