Term	Definition
Balanced translocation	Rearrangement of genetic material equally between chromosomes
Cell-free fetal DNA	Fetal DNA freely circulating in maternal blood; measured as part of aneuploidy screening for high-risk women
Combined test	First trimester measurement of hormones (beta subunit of human chorionic gonadotropin and pregnancy-associated plasma protein A) plus nuchal translucency
Fully integrated test	Combined test in first trimester plus quadruple screen in second trimester; screening report produced after both complete
Genetic mosaicism	Presence of more than one population of cells with different genotypes in a single individual
Nuchal translucency	Fluid-filled nuchal space (posterior neck) best visualized on ultrasonography between 11 and 14 weeks of gestation
Sequential contingent test	After initial screening report in first trimester, women at high risk are offered invasive diagnostic testing; women at moderate risk are offered further second trimester testing; and women at low risk have no further testing
Unbalanced translocation	Inheritance of a chromosome with extra or missing genetic material from a parent with a balanced translocation