title: Noninvasive prenatal diagnosis for single gene disorders.
abstract: OBJECTIVE
  Noninvasive prenatal diagnosis for single gene disorders is coming to fruition in its clinical utility. The presence of cell-free DNA in maternal plasma has been recognized for many years, and a number of applications have developed from this. Noninvasive prenatal diagnosis for single gene disorders has lagged behind due to complexities of technology development, lack of investment and the need for validation samples for rare disorders.
  
  
  RESULTS
  Publications are emerging demonstrating a variety of technical approaches and feasibility of clinical application. Techniques for analysis of cell-free DNA including digital PCR, next-generation sequencing and relative haplotype dosage have been used most often for assay development. Analysis of circulating fetal cells in the maternal blood is still being investigated as a viable alternative and more recently transcervical trophoblast cells. Studies exploring ethical and social issues are generally positive but raise concerns around the routinization of prenatal testing.
  
  
  CONCLUSIONS
  Further work is necessary to make testing available to all patients with a pregnancy at risk of a single gene disorder, and it remains to be seen if the development of more powerful technologies such as isolation and analysis of single cells will shift the emphasis of noninvasive prenatal diagnosis. As testing becomes possible for a wider range of conditions, more ethical questions will become relevant.
authors.affiliation: West Midlands Regional Genetics Laboratory, Birmingham Women's Hospital NHS Foundation Trust, Birmingham, UK.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Allen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Young
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bowns
mesh_terms: D000782:Aneuploidy; D002474:Cell-Free System; D005260:Female; D005796:Genes / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods* / Q000639:trends; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008403:Mass Screening / Q000379:methods* / Q000639:trends; D016133:Polymerase Chain Reaction / Q000379:methods; D017410:Practice Guidelines as Topic; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods* / Q000706:statistics & numerical data / Q000639:trends