title: Comparison of multiplex ligation-dependent probe amplification and karyotyping in prenatal diagnosis.
abstract: OBJECTIVE
  To estimate whether multiplex ligation-dependent probe amplification (MLPA), a molecular technique used for detecting the most common chromosomal aneuploidies, is comparable with karyotyping for the detection of aneuploidies of chromosomes X, Y, 13, 18, and 21 in routine clinical practice and to estimate the costs differences of both techniques.
  
  
  METHODS
  In this prospective, nationwide cohort study, we consecutively included 4,585 women who had an amniocentesis because of their age (36 years or older), increased risk after prenatal screening, or maternal anxiety. Amniotic fluid samples were tested independently with both MLPA and karyotyping. The primary outcome was diagnostic accuracy of MLPA to detect aneuploidies of chromosomes X, Y, 13, 18, and 21. Secondary outcome measures were turnaround time for test results and costs. A sample size was calculated using a critical noninferiority margin of 0.002; therefore, at least 4,497 paired test results were needed (one-sided alpha 0.05, power 0.90).
  
  
  RESULTS
  Diagnostic accuracy of MLPA was 1.0 (95% confidence interval [CI] 0.99-1.0), sensitivity was 100% (95% CI 0.96-1.0) and specificity was 100% (95% CI 0.999-1.0). Diagnostic accuracy of MLPA was statistically similar (noninferior) to that of karyotyping (P<.001). In 75 cases, MLPA failed (1.6%); karyotyping failed once (0.02%). Compared with karyotyping, MLPA shortened the waiting time by 14.5 days (P<.001, 95% CI 14.3-14.6) and cost less (-47, P<.001).
  
  
  CONCLUSIONS
  In routine clinical practice, diagnostic accuracy of MLPA for detection of trisomies X, Y, 13, 18, and 21 is comparable with that of karyotyping, and it reduces waiting time at lower costs.
  
  
  METHODS
  II.
authors.affiliation: From the Academic Medical Center Amsterdam, Amsterdam; Erasmus University Medical Center, Rotterdam; Leiden University Medical Center, Leiden; and University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Elisabeth M
authors.initials: EM
authors.lastname: Boormans
authors.forename: Erwin
authors.initials: E
authors.lastname: Birnie
authors.forename: Dick
authors.initials: D
authors.lastname: Oepkes
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Galjaard
authors.forename: Gijsbertha H
authors.initials: GH
authors.lastname: Schuring-Blom
authors.forename: Jan M
authors.initials: JM
authors.lastname: van Lith
mesh_terms: D000649:Amniocentesis; D000782:Aneuploidy; D003365:Costs and Cost Analysis; D005260:Female; D006801:Humans; D007621:Karyotyping; D021141:Nucleic Acid Amplification Techniques / Q000191:economics; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012680:Sensitivity and Specificity