Date of Award


Document Type

Thesis - Open Access

Degree Name

MS Human Genetics


Human Genetics Graduate Program


NIPT uptake in the general population has been rapidly increasing despite relatively low incidences of fetal aneuploidy in this cohort. This is further complicated by the inclusion of microdeletion syndromes, which have even lower positive predictive values (PPVs). This retrospective pilot study examines the performance and impact on patient decision making of a SNP-based NIPT in a general population cohort. A chart review was conducted of NIPT results from January 1, 2014 to August 24, 2015 at Montefiore Medical Center in the Bronx, NY. NIPT results were obtained for 3,747 samples. 1.33% of reports were high risk. One third of all high risk reports indicated a high risk for 22q11.2 deletion syndrome. 37.5% of women with high risk for 22q11.2DS elected diagnostic testing. None of the 5 whose diagnostic testing results were available were found to have an affected pregnancy. The total number of no call samples was 282 (7.53%). Cases in which the initial draw failed with low fetal fraction as a contributing factor had a redraw success rate of 28.75%. Differences in population characteristics can significantly impact the clinical utility of NIPT. The addition of conditions such as 22q11.2DS to NIPT panels will increase genetic counseling burden and complicate patient decision making. Overall, patients need to be aware that NIPT does not replace diagnostic testing, that PPVs differ significantly for microdeletion syndromes, and that redraw success is variable.