Foundations of Perinatal Genetic Counseling

Amber Mathiesen, MS, LCGC, is a licensed and board-certified genetic counselor in prenatal genetics at University of Utah Health, co-director of the perinatal genetics course at the University of Utah's Graduate Program in Genetic Counseling, and a prenatal rotation supervisor. She also acts as a research committee member and mentor for various genetic counseling students. Kali Roy, MS, LCGC, is a perinatal genetic counselor at University of Utah Health and co-director of the perinatal genetics course at the University of Utah's Graduate Program in Genetic Counseling. She graduated from the University of Utah Graduate Program in Genetic Counseling and completed a Master's of Science in Human Genetics and Genomics at the University of Connecticut.

Preface

Acknowledgments

Common Abbreviations

1. Pregnancy Basics

1.1 Pregnancy Timeline and Dating

Pregnancies are Counted in Weeks
Gestational Age versus Embryonic Age
Normal Pregnancy Timeline and Duration
Methods for Dating
Guidelines and Recommendations for Determining Dating
Tools Available for Calculating Gestational Age

1.2 Pregnancy Care

Types of Prenatal Providers
Routine Prenatal Visits
Prenatal Panel
Complete Blood Count
Blood Type and Antibody Testing
HbA1c for Diabetes
Fetal Imaging
Complicated Pregnancies

1.3 Documenting a Pregnancy History

Gravida and Para
Calculating Gravidity and Parity (G's and P's)

2. The Perinatal Genetic Counseling Appointment and Family History

2.1 The Perinatal Genetic Counseling Session

2.2 Obtaining a Pregnancy History

2.3 Obtaining a Family History

2.4 Interpreting a Family History

Mendelian Conditions
Multifactorial Conditions
Consanguinity
Birth Defects
Intellectual Disability and Autism
Pregnancy Loss and Infertility
Unknown Etiologies
Accuracy
Other Conditions (Referrals)

2.5 Unique Situations in the Perinatal Family History

Gamete Donation
Same Sex Couples
Surrogacy
Adoption
Ethnicity

3. Prenatal Screening

3.1 Evaluation of a Screen

Sensitivity
Specificity
Positive Predictive Value
Negative Predictive Value
Personal Utility

3.2 Prenatal Screening Options

Maternal Serum Screening

Multiples of the Median (MoM)
Calculating the Risk
Timing and Test Options
Results
Pattern Association
Follow up of Abnormal Results
Limitations of Maternal Serum Screening

Cell Free DNA Testing

Origin
Fetal fraction
Clearance
Methodology
Conditions Analyzed
Test performance
Who to offer testing to?
Multiples and Vanishing Twins
Adverse Pregnancy Outcomes
Considerations Prior to Testing
Results and Follow up
Resources

4. Prenatal Diagnosis

4.1 Techniques

Chorionic Villus Sampling

Twins
Risks
Limitations

Amniocentesis

Twins
Risks

4.2 Testing Options

Karyotype
Fluorescence in situ Hybridization (FISH)
Microarray
Molecular Testing
AFP &AChE
Other Testing

4.3 Indications for Diagnostic Testing

5. Common Indications

5.1 Age Related Risks

Maternal Age
Paternal Age

5.2 Personal and Family History

Single Gene Conditions
Aneuploidy
Multifactorial Conditions
Birth Defects
Intellectual Disability/Developmental Delay/Autism
Consanguinity

5.3 Ultrasound Anomalies

Counseling for Ultrasound Anomalies

Classification of Ultrasound Findings

Estimating Risks

Ultrasound Findings in Pregnancies with Aneuploidy

Down syndrome
Trisomy 18
Trisomy 13
Turner Syndrome
Triploidy
Common Ultrasound Findings
Hallmark Ultrasound Findings Associated with Genetic Conditions
Open Neural Tube Defects

5.4 Teratogens

5.5 Recurrent Pregnancy Loss, Stillbirth, and Infertility

Evaluation of Pregnancy Loss and Stillbirth

Evaluation of Infertility

Male Infertility
Female Infertility

5.6 Preconception Counseling

6. Carrier Screening

6.1 Background

Who Should be Offered Carrier Testing?
Carrier Screening for Gamete Donors
Timing of Screening
Evaluating Risks
Positive Test Results
Negative Results and Residual Risks
Other Types of Results
Application of a High Risk Result
Repeat Testing
Newborn Screening

6.2 Condition Directed or Ethnicity Based Testing

Cystic Fibrosis
Spinal Muscular Atrophy
FMR1-Related Disorders
Ashkenazi Jewish and French Canadian/Cajun
Hemoglobinopathies
Family History

6.3 Expanded Carrier Testing

7. Pregnancy Management

7.1 Reproductive Options

Continuation of Pregnancy
Adoption
Termination

First Trimester
Second Trimester
Later Term
Twins

7.2 Pregnancy Management Referrals

Maternal-Fetal Medicine Specialist
Specialized Imaging

3D Ultrasound
Echocardiography
MRI

Cardiology
Neonatology
Fetal Surgery/Intervention
Pediatric Surgery
Pediatric Specialists
Pathology/Autopsy
Palliative Care/Hospice

7.3 Support Referrals and Bereavement

8. Assisted Reproductive Technology and Reproductive Options for the At Risk Couple

8.1 Reproductive Options for At Risk Couples

8.2 Assisted Reproductive Techniques

8.3 Preimplantation Genetic Testing

Preimplantation Genetic Screening (PGS)
Preimplantation Genetic Diagnosis (PGD)

9. Common Perinatal Genetic Counseling Situations

9.1 Pregnancy Termination

Misinterpreted Intent
Patient Provider Conflict

9.2 Incidental Findings

Misattributed Paternity
Discovery of Consanguinity
Identification of an Incidental Condition

9.3 Privacy and Confidentiality

Genetics is a Family Affair
Secret Information

9.4 Working with couples

Couples in Conflict
"It's not my body"

9.5 Dealing with Uncertainty

Fetal Diagnosis and Prognosis
Family History
Complex Conditions
Variants of Uncertain Significance

9.6 Fetal Sex Disclosure

Patient's Desire to Know or Not
Testing may Reveal Sex Chromosome Abnormalities (SCAs)
Disorders Affecting a Specific Sex
Testing Only for Sex
Fetal Sex may be "Difficult News"

9.7 Patient Questions

"What would you do?"
When You Don't Know the Answer

9.8 Testing a Fetus for Adult Onset Condition

9.9 Barriers for Consent

Patient Understanding
Voluntary Participation

9.10 Rapidly Evolving Technologies

Appendix A

Appendix B

Index