title: Relationship between neonatal screening results by HPLC and the number of α-thalassaemia gene mutations; consequences for the cut-off value.
abstract: OBJECTIVE
  To evaluate the relationship between FAST peak percentage by adapted Bio-Rad Vnbs analysis using the valley-to-valley integration and genotypes with the aim to improve differentiation between severe α-thalassaemia forms (HbH disease) and the milder disease types.
  
  
  METHODS
  DNA analysis for α-thalassaemia was performed on 91 dried blood spot samples presenting normal and elevated FAST peak levels, selected during three years of Dutch national newborn screening.
  
  
  RESULTS
  Significant differences were found between samples with and without α-thalassaemia mutations, regardless of the genetic profiles. No significant difference was demonstrated between HPLC in -α/αα and -α/-α, between -α/-α and - -/αα and between - -/αα and - -/-α genotypes.
  
  
  CONCLUSIONS
  This study confirms that the percentage HbBart's, as depicted by the FAST peak, is only a relative indication for the number of α genes affected in α-thalassaemia. Based on the data obtained using the modified Bio-Rad Vnbs software, we adopted a cut-off value of 22.5% to discriminate between possible severe α-thalassaemia or HbH disease and other α-thalassaemia phenotypes. Retrospectively, if this cut-off value was utilized during this initial three-year period of neonatal screening, the positive predictive value would have been 0.030 instead of 0.014.
authors.affiliation: National Institute for Public Health and the Environment, Laboratory for Infectious Diseases and Perinatal Screening, A. van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands. marelle.bouva@rivm.nl
authors.forename: M J
authors.initials: MJ
authors.lastname: Bouva
authors.forename: C
authors.initials: C
authors.lastname: Sollaino
authors.forename: L
authors.initials: L
authors.lastname: Perseu
authors.forename: R
authors.initials: R
authors.lastname: Galanello
authors.forename: P C
authors.initials: PC
authors.lastname: Giordano
authors.forename: C L
authors.initials: CL
authors.lastname: Harteveld
authors.forename: M H
authors.initials: MH
authors.lastname: Cnossen
authors.forename: P C J I
authors.initials: PC
authors.lastname: Schielen
authors.forename: L H
authors.initials: LH
authors.lastname: Elvers
authors.forename: M
authors.initials: M
authors.lastname: Peters
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D004252:DNA Mutational Analysis; D005312:Fetal Blood / Q000737:chemistry; D005820:Genetic Testing / Q000379:methods*; D006447:Hemoglobin H / Q000032:analysis / Q000235:genetics; D006455:Hemoglobins, Abnormal / Q000032:analysis / Q000235:genetics; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007231:Infant, Newborn; D009154:Mutation; D015997:Neonatal Screening / Q000379:methods*; D009426:Netherlands; D012189:Retrospective Studies; D055542:alpha-Globins / Q000032:analysis / Q000235:genetics; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis* / Q000235:genetics*
chemical_list: D006455:Hemoglobins, Abnormal; D055542:alpha-Globins; D006447:Hemoglobin H; C030448:hemoglobin Bart's