Clinical Genetics Resources
See Also: Genetic Counselor’s Toolbox
Genetic Counseling Services
Prenatal Screening & Carrier Testing
Patient Resources
Prenatal Genetic Testing — Clinical Workflow
Step 1: Pretest Review
Family history, aneuploidy risk factors, prior trisomy, maternal age.
Family history, aneuploidy risk factors, prior trisomy, maternal age.
Step 2: Screening
• cfDNA (primary)
• First-trimester screening ± NT
• Quad screen (secondary indications)
• cfDNA (primary)
• First-trimester screening ± NT
• Quad screen (secondary indications)
Step 3: Diagnostic Confirmation if Positive
CVS (11–13 wks) or Amniocentesis (≥15 wks)
→ Karyotype ± Microarray
CVS (11–13 wks) or Amniocentesis (≥15 wks)
→ Karyotype ± Microarray
Clinical Interpretation Pathways — Screening → Diagnostic Decisions
cfDNA Result Interpretation
Low-risk cfDNA → Routine Care
Residual risk ↑ with obesity, twins, donor eggs; pursue diagnostics if anomalies present.
Residual risk ↑ with obesity, twins, donor eggs; pursue diagnostics if anomalies present.
High-risk cfDNA → Diagnostic Confirmation Required
CVS/Amnio → Karyotype ± Microarray ± Exome
CVS/Amnio → Karyotype ± Microarray ± Exome
No-call cfDNA
Repeat only if technical cause likely; otherwise proceed to diagnostic testing.
Repeat only if technical cause likely; otherwise proceed to diagnostic testing.
Sex Chromosome Aneuploidy
Higher FP rate; consider mosaicism & tissue discordance.
Higher FP rate; consider mosaicism & tissue discordance.