title: Cystathionine beta-synthase deficiency: effects of betaine supplementation after methionine restriction in B6-nonresponsive homocystinuria.
abstract: OBJECTIVE
  For treatment of cystathionine beta-synthase (CbetaS) deficiency, we determined the effect of betaine (N,N,N-trimethylglycine) therapy and examined the genotype-phenotype relationships to betaine.
  
  
  METHODS
  In five patients with B6-nonresponsive homocystinuria, we defined the CbetaS genotypes and determined metabolic responses to betaine as an additive to traditional dietary methionine restriction.
  
  
  RESULTS
  After betaine therapy, tHcy declined (mean 47.4 micromol/L; range: -21.2 to -104.0 micromol/L; P=0.02), whereas total plasma cysteine and methionine did not change. Plasma methionine/tHcy ratios increased by 5.45 (range: +1.5 to 15.3; P=0.05) inpatients with B6-nonresponsive alleles.
  
  
  CONCLUSIONS
  Betaine improves metabolic control in B6-nonresponsive patients with homocystinuria after optimum dietary control.
authors.affiliation: Division of Medical Genetics, Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Rani H
authors.initials: RH
authors.lastname: Singh
authors.forename: Warren D
authors.initials: WD
authors.lastname: Kruger
authors.forename: Liqun
authors.initials: L
authors.lastname: Wang
authors.forename: Marzia
authors.initials: M
authors.lastname: Pasquali
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Elsas
mesh_terms: D000293:Adolescent; D000328:Adult; D001622:Betaine / Q000378:metabolism / Q000627:therapeutic use*; D002648:Child; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003541:Cystathionine beta-Synthase / Q000235:genetics; D003545:Cysteine / Q000097:blood; D017931:DNA Primers; D019587:Dietary Supplements; D005838:Genotype; D006710:Homocysteine / Q000097:blood* / Q000378:metabolism; D006712:Homocystinuria / Q000188:drug therapy* / Q000235:genetics; D006801:Humans; D007223:Infant; D008715:Methionine / Q000097:blood; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D006710:Homocysteine; D001622:Betaine; D008715:Methionine; D003541:Cystathionine beta-Synthase; D003545:Cysteine