August 2019

“The Art of Genetic Counseling in the Era of Genomic Testing” at ISPD 2019.

By Kelly Chen, MS and Katie Ellis, MS, Co-Chairs Genetic Counseling SIG

“How do I explain non-paternity in a tactful manner?”

“Should I discuss the potential impact of knowing about adult-onset diseases through prenatal microarray?”

How do I counsel a patient with an ongoing pregnancy (following mosaic embryo transfer) who will only consider noninvasive screening options?

Are these questions that you consider when counseling patients?  If they are, please join us in Singapore on Tuesday 10 September 2019 at the Genetic Counseling special interest group breakfast session of ISPD2019.  Everyone is welcome to attend as our expert speakers walk us through the challenges of pre-test counseling for complex genomic tests and share their experiences and strategies used when speaking to patients about the details of testing.

Our speakers

Christina Choi, MS, CGC is the Principal Genetic Counselor at the Antenatal Diagnostic Centre at KK Women’s and Children’s Hospital (KKH). Christina joined KKH in 2012 and as a prenatal genetic counselor with the Fetal Medicine team, where she provides genetic counseling to high risk pregnancies. She received her B.A. in Biology and M.S. in Biotechnology from Johns Hopkins University and an M.S. in Genetic Counseling from Boston University School of Medicine. She worked in the San Francisco Bay Area as a prenatal genetic counselor in a private obstetrics practice and was also involved in early startup days of Counsyl Inc. Christina is board certified with the American Board of Genetic Counselling.

 



Katie Ellis, Genetic Counseling IPSD SIG Co-Chair founded the Clinical Genetics unit for Canberra (Australia) and surrounds in 1997 and provided guidance for the establishment of the Clinical Genetics units in other Australian Territories and has participated in several advisory boards in Australia. She headed and expanded the ACT service over the next 15 years. Katie has been involved in all aspects of Genetic Counselling and was the youngest individual to be awarded Part II Genetic Counselling by the Human Genetic Society of Australasia. Katie also has a Graduate Diploma in Higher Education and lectures at a number of Australian Universities. Katie is currently Genea’s Senior Genetic Counselor. Katie also loves being a mum to four young daughters.



During our interactive breakfast session, our invited speakers will be sharing their expertise on the following topics.

1. Pretest counselling for Prenatal Chromosome Microarray (CMA)

The growing use of chromosomal microarray for prenatal diagnosis has increased the complexity of pre-test genetic counseling. 



(image from: Karampetsou E, Morrogh D, Chitty L. J Clin Med 2014;3:66378.)

The 2016 ACOG/SMFM guideline provided a sample script and recommended points to be covered in the pre-test counseling for CMA. These include:

  • Differences between CMA and routine karyotype analysis
  • Conditions identified and not identified
  • Severity of phenotype may not be predictable
  • Consanguinity or nonpaternity
  • Variants of unknown significance (VUS) and the need for parental testing
  • Identification of adult-onset diseases

In the same year the ACOG guideline was updated, a study surveyed the NSGC membership about their use of CMA.  Of 183 genetic counselors who incorporated CMA into their clinical practices, 96% or more discussed the pre-test points about pathogenic results, the possibility of not being able to predict the severity of a phenotype, and the possibility of a VUS.  However, fewer discussed the additional points of parental implications (74%),  incidental findings (68%) and adult-onset diseases (48%).  The reasons for the decreased frequencies were not explored, but could be related to lack of time or other barriers in the delivery of these complex topics.  While guidelines address the topics which should be covered in pretest counseling, the study proposed that future guidelines, particularly those set forth by NSGC, should expand to include suggestions for counseling strategies.

In Asia, the provision of genetic counseling is further complicated by the large gap in genetic counseling professionals in proportion to the population.(Cutiongco-de la Paz EM, et al. Am J Med Genet C Semin Med Genet. 2019 Jun;181(2):177-186.)  In addition, the cultural, religious, social, and healthcare system diversity within the region can create potential challenges in developing universal guidelines for the provision of genetic counseling.

“How do genetic counselors avoid throwing everything but the kitchen sink at patients and still make sure that patients walk away from the sessions with all the important points?” asks Principal Genetic counselor Christina Choi.  In the breakfast session, Christina will highlight these challenges and her experience in a brief presentation. This will be followed by an interactive workshop where attendees will break out into small groups. Attendees will then be encouraged to share experiences and thoughts about each of the guideline-suggested CMA points as well as strategies to approaching complex and difficult topics with patients.

2. Prenatal Testing for Mosaic Embryos

Genetic specialists are familiar with mosaic results when ordering genetic testing in children or adults, but with recent advances in pre-implantation genetic testing for aneuploidy (PGT-A), this concept has been brought into the realm of prenatal diagnosis and screening.

Fertility clinics have offered preimplantation genetic screening (PGS; now termed PGT-A) for many years with the purpose of selective transfer of only those embryos deemed euploid in the hopes of better outcomes (lower miscarriage rates and higher birth rates). Previous technologies generally resulted in discrete results for the patients (euploid or aneuploid).

In recent years, array CGH and next generation sequencing (NGS) has allowed the detection of mosaic euploid/aneuploid embryos and quantification of copy number changes present (generally as a percentage). This has raised challenges for genetic counselors as there is a paucity of literature on the clinical significance of the findings. Much of the current literature centers around the need for detailed genetic counseling at the time of the results so that patients can make an informed decision about whether they wish to transfer, discard or store the embryo. Although mosaic embryos are viewed as a last preference for transfer, more patients are electing to transfer mosaic embryos, particularly if this is the final option for pregnancy. There is a greater demand for prenatal genetic counselors or clinicians to have an understanding of the issues and to provide prenatal counseling when an ongoing pregnancy is achieved from mosaic embryo transfer.

(image from: Vera-Rodriguez M, Rubio C. Fertil Steril. 2017 May;107(5):1107-1112)

Initially the recommendations were that women should be offered prenatal diagnosis in the form of amniocentesis following transfer of the mosaic embryo. Chorionic villus sampling was not encouraged as it may reveal the mosaicism as previously reported. PGT-A testing examines cells from the outer layer (trophectoderm) of the embryo so the cells in the inner cell mass (that then differentiate to fetal cells) could have a different composition. Amniocentesis would therefore provide more fetal information.

In May 2019, the Preimplantation Genetic Diagnosis International Society (PGDIS) released a new position statement on the transfer of mosaic embryos in PGT-A. The updated statement states: “Prenatal diagnosis of the fetus and placenta of any established pregnancy after PGT is highly recommended. Amniocentesis analysis from week 14 onwards is currently considered to be the most representative of the fetus genetics. For earlier investigations of the placenta, consideration can also be given to NIPT methodology that analyses placental copy number of all 24 chromosomes - simple 5 chromosome NIPT tests for chromosomes 21, 18, 13, X and Y may not be appropriate. Ultrasound may also be helpful in identifying fetal abnormalities while PAPP-A screening and Doppler ultrasound may also be useful in identifying placental malfunction.”

Katie Ellis, Genetic Counseling SIG Co-Chair and genetic counselor, will provide a brief presentation on this topic, followed by an interactive workshop to explore these issues further.

Everyone is welcome at the GC SIG breakfast meeting – see you in Singapore next month! For any enquiries about our SIG, please email us at km_chen@yahoo.com or katie.ellis@genea.com.au