ACOG Endorses Expanded Carrier Screening and Recommends Surrounding It With Genetic Counseling
Committee Opinion Number 690 (March 2017) just issued by the American College of Obstetricians and Gynecologists endorses, for the first time, expanded carrier screening as an acceptable strategy for preconception and prenatal carrier screening. The Opinion is grounded in a set of Recommendations that emphasize the importance of genetic counseling as the centerpiece of offering carrier screening to patients. The role of genetic counseling to support practitioners in their efforts to provide complete and high quality care is expanding in direct proportion to the complexity of carrier screening. Labs are including an increasing number of genes that can have a detrimental effect on quality of life for a child. The ACOG recommendation underscores the importance of testing patients with knowledgeable and sensitive pretest counseling as well as post-test communication of results.
The Committee Opinion set forth 11 Recommendations… all of which are consistent with past and current practices of Insight Medical Genetics. To summarize as well as highlight what is new and/or different compared to previous Opinions and Recommendations:
- Expanded panethnic panels are acceptable strategies for carrier screening. Ideally, screening options are discussed and offered before pregnancy.
- These recent recommendations now support screening for Spinal Muscular Atrophy (SMA). The accompanying Committee Opinion, Number 691, continues to support and further describes screening for Cystic Fibrosis for all women in addition to hemoglobinopathies and Fragile X for women with appropriate indications.
- Counseling on limitations, benefits, and alternatives should accompany any offer for testing. Carrier couples identified preconceptually should be offered genetic counseling to understand all of their reproductive options.
- If an individual is found to be a carrier, her/his reproductive partner should be offered reflex testing and accurate genetic counseling regarding risks of having an affected child as well as information regarding the specific condition, residual risk, and options for prenatal testing.
- Identification of a family history of a genetic disorder and the specific familial mutation(s) can allow for more specific and rapid prenatal diagnosis.
- While inclusion criteria for expanded panel screening are still evolving, conditions with a well-defined phenotype, a detrimental effect on quality of life, an impact on cognitive or physical development, requirements for surgical or medical intervention, or early onset in life form the strongest bases for formulating a screening panel. Carrier frequency is an option and the capacity for pathogenic variants to be diagnosed prenatally adds to the decision-making regarding inclusion in a panel. Adult onset conditions should not be included in carrier screening panels
Insight’s Newly Expanded Carrier Screening Panel.
It’s No Longer Only About the Child-To-Be.
We have believed for several years in the value of expanded, panethnic carrier screening basis accompanied by genetic counseling to insure a sound informed consent process. In applying this through the use of full gene sequencing to maximize the identification of pathogenic variants, we have learned a great deal from experiences with patients on translating the complexities of carrier screening. Additionally, Insight’s laboratories have developed the capacity for targeted sequencing based reflex testing for reproductive partners for most of the genes found on the expanded screening panels offered by most laboratories. And, Insight’s laboratories are qualified and experienced in providing prenatal diagnoses for virtually all the relevant genes when carrier couples are identified.
Recently, we have expanded the number of target genes on the sequencing panel we offer from 75 to 165 which are associated with over 140 well-described medical conditions. In so doing, our staff – clinical geneticists, genetic counselors, and lab personnel – reviewed each potential gene to be included and selected only those that are consistent with ACOG’s recommendations regarding severity of outcomes.
Importantly, we have recognized that an increasing number of conditions and genes that are appropriate to screen for carrier status may also have important health implications for the adult individual identified to be a heterozygote carrier! There are 16 such conditions on the panel Insight is offering. In addition, there are a greater number of X-linked conditions on the panel which leads to a different counseling approach than is typically the case, including eliminating the need to test the male partners of carrier women.
These considerations highlights again the importance of surrounding carrier screening with genetic counseling, pre-and post-test.
Jeffrey Dungan, MD, FACOG, FACMG
Lee Shulman, MD, FACOG, FACMG
Andrew Wagner, MD, FACOG, FACMG
Morry Fiddler, PhD