title: MALDI-TOF-MS Assay to Detect the Hemizygous 22q11.2 Deletion in DNA from Dried Blood Spots.
abstract: BACKGROUND
  A hemizygous deletion of 1.5-3 Mb in 22q11.2 causes a distinct clinical syndrome with variable congenital defects. Current diagnostic methods use fluorescent in situ hybridization (FISH) or comparative genomic hybridization by microarray to detect the deletion. Neither method is suitable for newborn screening (NBS), since they cannot be performed on dried blood spots (DBS). We developed a MALDI-TOF-MS assay that uses DBS to measure the hemizygous deletion of UFD1L, located within the 22q11.2 region.
  
  
  METHODS
  We used DBS from 54 affected patients, previously tested by FISH or microarray, and 100 cord blood samples to evaluate the performance of the MALDI-TOF-MS assay. With a single primer pair, a 97-base oligonucleotide within UFD1L was amplified, as was a sequence on chromosome 18 that differs by 2 nucleotides. A multiplexed, single-base extension reaction created allele-specific products for MALDI-TOF-MS detection. The products were spotted onto a silicon chip, and the height of the spectral peaks identified the relative amounts of target and reference gene.
  
  
  RESULTS
  The median ratio of the spectral peak for each UFD1L target:reference base was 0.96 and 0.99 for controls, compared with 0.35 and 0.53 for 22q11 deletion syndrome patients. There was 100% concordance between FISH/microarray and MALDI-TOF-MS in all patients with 22q11.2 deletion syndrome.
  
  
  CONCLUSIONS
  This method can be reliably performed with DBS and is suitable for high sample throughput. This assay may be considered for use in population-based NBS for 22q11.2 deletion.
authors.affiliation: Department of Pediatrics, Allergy and Immunology Section, Emory University School of Medicine, Atlanta, GA; lkobryn@emory.edu.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Kobrynski
authors.affiliation: Newborn Screening Translational Research Initiative, CDC Foundation, Atlanta, GA;
authors.forename: Golriz K
authors.initials: GK
authors.lastname: Yazdanpanah
authors.affiliation: Newborn Screening and Molecular Biology Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Koontz
authors.affiliation: Newborn Screening and Molecular Biology Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Francis K
authors.initials: FK
authors.lastname: Lee
authors.affiliation: Newborn Screening and Molecular Biology Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Vogt
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport; D004247:DNA / Q000235:genetics*; D059788:Dried Blood Spot Testing; D017353:Gene Deletion; D057898:Hemizygote; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins / Q000235:genetics*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C491497:UFD1 protein, human; D004247:DNA