Studying for the Genetic Counseling Board Exam: A Look at Prenatal Study Resources

As we start off 2024, I think back to the whirlwind start of 2023. Not only was it the start of my final semester of my genetic counseling graduate program, but also the start of the year that I would be taking the American Board of Genetic Counseling (ABGC) Certification Examination. The anxiety and excitement generated motivation to study throughout the semester and into the summer.

Every student’s studying processes look different. However, there was one consistent piece of advice I received time and time again that rang true: “If you put in the time, it will be fine.” This grandiose statement was somehow both daunting and reassuring, as it left me asking myself, “Well, what do I fill that time with?”

The first step to answering that question is to break down the exam into more digestible segments, which will help not only with overwhelming stress, but also with creating an organization system that truly best supports long-term memory.

In that spirit, the rest of this article will reveal some of my own top resources for studying specifically for the prenatal content on the ABGC Certification Examination.

Prenatal Screening and Testing

One of the main prenatal genetic counseling topics (as listed on the content outline) is prenatal screening and follow-on testing options. Prenatal screening and testing options evolve rapidly. Thus, it is important to be familiar both with options that are currently used in clinical practice (e.g., cell-free DNA screening), as well as those that may have been used historically (e.g., first-trimester screening or quad screen).

A great resource for beginning your study of prenatal screening and testing is Chapter 17 of Thompson & Thompson’s Genetics in Medicine (Nussbaum et al., 2016). Of note, there is a new (ninth) edition, which can be a useful resource as well (Cohn et al., 2024). This chapter covers topics such as prenatal ultrasonography and serum screening (MSAFP, first-trimester screening, cell-free DNA, as well as diagnostic testing options (such as chorionic villus sampling, amniocentesis, cytogenetic studies, and molecular diagnostics).

Thompson & Thompson (2016) is also a place to review chromosomal conditions that may be identified through prenatal screening or testing. Chapter 6, “The Chromosomal and Genomic Basis of Disease: Disorders of the Autosomes and Sex Chromosomes,” reviews the major genetic and natural history features of whole chromosome aneuploidies and microdeletion/duplications. This book also provides relevant case examples as supplemental information, which can help solidify your mental image of a particular condition. For example, in this edition of the book, Case 47 (p.484) reviews Turner syndrome.

Another helpful review resource for chromosomal differences is Harper’s Practice Genetic Counseling (Clarke, 2020). This book is more of a quick reference than a deep-dive, but Chapter 4 of the eighth edition provides a concise review of cytogenetic differences — such as inversions, translocations and uniparental disomy. I would also recommend reading Parts 4 and 7 of Gardner, et. al. (2012): “Normal Parents with a Chromosomally Abnormal Child” and “Prenatal Diagnosis.”

Again, in thinking about tying together both prenatal screening and consequent testing with chromosomal aneuploidy, it is important to review the NSGC practice guideline: Prenatal Screening and Diagnostic Testing Options for Chromosome Aneuploidy (Wilson et al., 2012). This guideline, as well as the others provided by NSGC, must be familiar so you can navigate questions that ask for the best path for screening and testing, including specific recommendations provided based on a patient’s circumstance. Also, it is important to familiarize yourself with NSGC’s position statement on prenatal cell-free DNA screening (2021).

Carrier screening is another important aspect of prenatal genetic counseling. The ABGC Certification Examination expects test takers to understand the goals of population-based carrier screening and apply its principles to specific cases (e.g., low- versus high-risk family history, ancestry and consanguinity considerations, etc.). To begin, Harper’s guide provides a chapter (7) dedicated to reviewing carrier screening principles (Clarke, 2020, pg. 123-144).

There are quite a few guidelines that are relevant to carrier screening that are also important to review. The American College of Medical Genetics’ (ACMG) more recent practice guideline publication provides recommendations for a pan-ethnic approach to carrier screening (Gregg et al., 2021). I would also intimately familiarize yourself with The American College of Obstetricians and Gynecologists’ (ACOG) committee opinion regarding carrier screening (2017), and the National Society of Genetic Counselor’s practice guideline on expanded carrier screening (Sagaser et al., 2023).

The content area of prenatal screening allows the exam to assess your understanding of test parameters, such as sensitivity and specificity. I recommend doing some practice calculations of these test parameters. A great resource for understanding the terminology around test performance is Chapter 9 of A Guide to Genetic Counseling by Uhlmann et. al. (2009). Specifically, in the second edition, pages 283-292 provide relevant information. This information is also reviewed in Thompson & Thompson (2016) in Chapter 18 (p. 376-377).

Embryology and Birth Defects

As I started my studying of developmental genetics and birth defects, I paused to remind myself that no one is expecting us to graduate from a genetic counseling training program as an embryologist! At least for me, it was easy to get lost in the weeds and complexities of embryology. When it comes to the board examination — and clinical practice — our knowledge of human development is meant to serve the genetic counseling goals of providing patient-driven education, identifying potential etiologies and counseling about any appropriate options for genetic testing. Thus, studying for this content area should be focused on linking differences in development to a specific set of differentials.

For example, when you think of “prenatally identified cleft palate,” what are the first topics that come to mind? After studying, you should be able to generate ideas about what other information you might need, as well as what you might share with the patient. For example, is it an isolated finding? Timing of development? Has the patient had low-risk cell-free DNA screening for aneuploidy? Chromosomal, versus single gene, versus multifactorial?

It takes practice to get to a place where it is comfortable to make these lists for many differences in development. Again, a helpful jumping-off place will be Thompson & Thompson, Chapter 14, “Developmental Genetics and Birth Defects” (2016).  I would also recommend reviewing the information from Mother to Baby on the critical periods of development.

Subsequently, I dove into Harper’s Practical Guide to Genetic Counseling (Clarke, 2020), beginning with Chapter 6, “Dysmorphology and Genetic Syndrome.” Each chapter of part two of the book breaks down genetic counseling concepts by specific organ systems. This part of the book is very helpful for studying pediatric genetic conditions, but also has significant overlap with prenatally identified differences in development, such as those covered in chapters 16, 17, 21, 23 and 24.

Also, don’t forget to go back to your notes from graduate school. The slides I received from my instructors were hugely helpful, and I made many flashcards from the information taken directly from them.

Teratogens

There are many substances that are teratogenic. It is best to familiarize yourself with some of the more common infections, medications and conditions that affect pregnant people, as well as how they would impact prenatal development, maternal care and genetic counseling.

Mother to Baby is a wonderful resource that has fact sheets about many teratogenic exposures (Organization of Teratology Information Specialists, 2023). There are many circulating lists among genetic counseling students with relevant exposures to be familiar with that I used to guide my studying. At a minimum, I would recommend the following (again, this is based on my experience and others’ who have studied — it is possible for the board exam to include other exposures): toxoplasmosis, cytomegalovirus, rubella, parvovirus, varicella, zika, syphilis, herpes simplex virus, fever, alcohol, cigarette smoke, lithium, ACE inhibitors, thalidomide, valproic acid, isotretinoin, poorly controlled maternal diabetes and poorly controlled maternal phenylketonuria, among others.

Tying It All Together

Studying for the ABGC Certification Examination is a huge time commitment. The best way to ensure you’re using your time appropriately is to create a structure and identify the appropriate resources prior to beginning to study. Hopefully, you can use the information and references from this guide as a jumping-off point, knowing that it is not the end-all, be-all, but rather is a great place to start to review, identify your strengths and address your weaknesses. Best of luck!

References

American College of Obstetricians and Gynecologists. (2017). Committee Opinion Number 691:

Carrier Screening for Genetic Conditions. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/03/carrier-screening-for-genetic-conditions

Clarke, A. J., & Harper, P. S. (2020). Harper’s Practical Genetic Counseling (8th Edition). CRC Press.

Cohn, R. D., Scherer, S. W., Hamosh, A., & Thompson, J. S. (2024). Thompson & Thompson Genetics and genomics in medicine (9th edition). Elsevier.

Gregg, A.R., Aarabi, M., Klugman, S. et al. (2021).  Screening for autosomal recessive and X-linked

conditions during pregnancy and preconception: a practice resource of the American College of Medical Genetics and Genomics (ACMG). Genet Med 23, 1793–1806.

https://doi.org/10.1038/s41436-021-01203-z

Organization of Teratology Information Specialists. Fact sheets. MotherToBaby. (2023, December

19). https://mothertobaby.org/fact-sheets/

Nussbaum, R. L., McInnes, R. R., & Willard, H. F. (2016). Thompson & Thompson Genetics in Medicine

(8th Edition). Elsevier.

Prenatal cell-free DNA screening (2021, April 23). National Society of Genetic Counselors.

https://www.nsgc.org/POLICY/Position-Statements/Position-Statements/Post/prenatal-cell-free-dna-screening-1

Sagaser, K. G., Malinowski, J., Westerfield, L., et al. (2023). Expanded carrier screening for

reproductive risk assessment: An evidence-based practice guideline from the National Society of Genetic Counselors. Journal of Genetic Counseling, 32, 540–557. https://doi.org/10.1002/jgc4.1676

Uhlmann, W. R., Schuette, J. L., & Yashar, B. M. (2009). A guide to genetic counseling (Second Edition).

Wiley-Blackwell.

Wilson, K. L., Czerwinski, J. L., Hoskovec, J. M., Noblin, S. J., Sullivan, C. M., Harbison, A., Campion,

M. W., Devary, K., Devers, P., & Singletary, C. N. (2012). NSGC practice guideline: Prenatal screening and diagnostic testing options for chromosome aneuploidy. Journal of Genetic Counseling, 22(1), 4–15. https://doi.org/10.1007/s10897-012-9545-3