title: Size fractionation of cell-free DNA in maternal plasma improves the detection of a paternally inherited beta-thalassemia point mutation by MALDI-TOF mass spectrometry.
abstract: OBJECTIVE
  The selective enrichment of cell-free fetal DNA in maternal plasma by size fractionation leads to the improved detection of paternally inherited fetal point mutations when using conventional, real-time PCR, or as has more recently been shown by MALDI-TOF mass spectrometry. We have now examined the use of size fractionation in conjunction with mass spectrometry for the detection of a paternally inherited codon 39 mutation of the beta-globin gene.
  
  
  METHODS
  Maternal plasma was obtained from an early second trimester pregnancy at risk for beta-thalassemia, where the father carried the codon 39 mutation and the mother was a carrier for the IVSI-110 mutation of the beta-globin gene. Cell-free DNA was analyzed by mutation-specific PCR and MALDI-TOF mass spectrometry for the presence of the codon 39 mutation. A comparison was made between total cell-free DNA and that which had been enriched for a size of 100-300 bp.
  
  
  RESULTS
  The paternally inherited codon 39 mutant allele was detectable in both cell-free DNA preparations, but the signal was much more pronounced and precise in the size-fractionated sample.
  
  
  CONCLUSIONS
  Size fractionation of cell-free DNA may lead to the improved non-invasive detection of fetal point mutations for beta-thalassemia by MALDI-TOF mass spectrometry.
authors.affiliation: University Women's Hospital, Department of Biomedicine, University Hospital Basel, Basel, Switzerland.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Edoardo
authors.initials: E
authors.lastname: Di Naro
authors.forename: Angeloantonio
authors.initials: A
authors.lastname: Vitucci
authors.forename: Simon
authors.initials: S
authors.lastname: Grill
authors.forename: Xiao Yan
authors.initials: XY
authors.lastname: Zhong
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Holzgreve
authors.forename: Sinuhe
authors.initials: S
authors.lastname: Hahn
mesh_terms: D000328:Adult; D005591:Chemical Fractionation; D004247:DNA / Q000097:blood*; D005260:Female; D005333:Fetus / Q000166:cytology*; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D008297:Male; D008431:Maternal-Fetal Exchange; D017354:Point Mutation; D011247:Pregnancy; D011296:Prenatal Diagnosis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017086:beta-Thalassemia / Q000235:genetics*
chemical_list: D004247:DNA