Non-invasive prenatal detection of trisomy 21 using tandem single nucleotide polymorphisms. PLoS One 2010 Oct 08;5(10):e13184
Date
10/16/2010Pubmed ID
20949031Pubmed Central ID
PMC2951898DOI
10.1371/journal.pone.0013184Scopus ID
2-s2.0-78149464048 (requires institutional sign-in at Scopus site) 17 CitationsAbstract
BACKGROUND: Screening tests for Trisomy 21 (T21), also known as Down syndrome, are routinely performed for the majority of pregnant women. However, current tests rely on either evaluating non-specific markers, which lead to false negative and false positive results, or on invasive tests, which while highly accurate, are expensive and carry a risk of fetal loss. We outline a novel, rapid, highly sensitive, and targeted approach to non-invasively detect fetal T21 using maternal plasma DNA.
METHODS AND FINDINGS: Highly heterozygous tandem Single Nucleotide Polymorphism (SNP) sequences on chromosome 21 were analyzed using High-Fidelity PCR and Cycling Temperature Capillary Electrophoresis (CTCE). This approach was used to blindly analyze plasma DNA obtained from peripheral blood from 40 high risk pregnant women, in adherence to a Medical College of Wisconsin Institutional Review Board approved protocol. Tandem SNP sequences were informative when the mother was heterozygous and a third paternal haplotype was present, permitting a quantitative comparison between the maternally inherited haplotype and the paternally inherited haplotype to infer fetal chromosomal dosage by calculating a Haplotype Ratio (HR). 27 subjects were assessable; 13 subjects were not informative due to either low DNA yield or were not informative at the tandem SNP sequences examined. All results were confirmed by a procedure (amniocentesis/CVS) or at postnatal follow-up. Twenty subjects were identified as carrying a disomy 21 fetus (with two copies of chromosome 21) and seven subjects were identified as carrying a T21 fetus. The sensitivity and the specificity of the assay was 100% when HR values lying between 3/5 and 5/3 were used as a threshold for normal subjects.
CONCLUSIONS: In summary, a targeted approach, based on calculation of Haplotype Ratios from tandem SNP sequences combined with a sensitive and quantitative DNA measurement technology can be used to accurately detect fetal T21 in maternal plasma when sufficient fetal DNA is present in maternal plasma.
Author List
Ghanta S, Mitchell ME, Ames M, Hidestrand M, Simpson P, Goetsch M, Thilly WG, Struble CA, Tomita-Mitchell AAuthors
Aoy Tomita Mitchell PhD Professor in the Surgery department at Medical College of WisconsinPippa M. Simpson PhD Adjunct Professor in the Pediatrics department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
Down SyndromeFemale
Haplotypes
Humans
Polymerase Chain Reaction
Polymorphism, Single Nucleotide
Pregnancy
Prenatal Diagnosis
