Clinical Review

2020 Update on fertility

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ACOG guidelines on preconception genetic carrier screening, AI and embryo selection, and the hidden dangers of environmental toxicants and ways to mitigate them



Although we are not able to cover all of the important developments in fertility medicine over the past year, there were 3 important articles published in the past 12 months that we highlight here. First, we discuss an American College of Obstetricians and Gynecologists (ACOG) committee opinion on genetic carrier screening that was reaffirmed in 2019. Second, we explore an interesting retrospective analysis of time-lapse videos and clinical outcomes of more than 10,000 embryos from 8 IVF clinics, across 4 countries. The authors assessed whether a deep learning model could predict the probability of pregnancy with fetal heart from time-lapse videos in the hopes that their research can improve prioritization of the most viable embryo for single embryo transfer. Last, we consider a review of the data on obstetric and reproductive health effects of preconception and prenatal exposure to several environmental toxicants, including heavy metals, endocrine-disrupting chemicals, pesticides, and air pollution.

Preconception genetic carrier screening: Standardize your counseling approach

American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 690: carrier screening in the age of genomic medicine. Obstet Gynecol. 2017;129:e35-e40.

With the rapid development of advanced and high throughput platforms for DNA sequencing in the past several years, the cost of genetic testing has decreased dramatically. Women's health care providers in general, and fertility specialists in particular, are uniquely positioned to take advantage of these novel and yet affordable technologies by counseling prospective parents during the preconception counseling, or early prenatal period, about the availability of genetic carrier screening and its potential to provide actionable information in a timely manner. The ultimate objective of genetic carrier screening is to enable individuals to make an informed decision regarding their reproductive choices based on their personal values. In a study by Larsen and colleagues, the uptake of genetic carrier screening was significantly higher when offered in the preconception period (68.7%), compared with during pregnancy (35.1%), which highlights the significance of early counseling.1

Based on the Centers for Disease Control and Prevention's Birth/Infant Death Data set, birth defects affect 1 in every 33 (about 3%) of all babies born in the United States each year and account for 20% of infant mortality.2 About 20% of birth defects are caused by single-gene (monogenic) disorders, and although some of these are due to dominant conditions or de novo mutations, a significant proportion are due to autosomal recessive, or X-chromosome linked conditions that are commonly assessed by genetic carrier screening.

ACOG published a committee opinion on "Carrier Screening in the Age of Genomic Medicine" in March 2017, which was reaffirmed in 2019.3

Residual risk. Several points discussed in this document are of paramount importance, including the need for pretest and posttest counseling and consent, as well as a discussion of "residual risk." Newer platforms employ sequencing techniques that potentially can detect most, if not all, of the disease-causing variants in the tested genes, such as the gene for cystic fibrosis and, therefore, have a higher detection rate compared with the older PCR-based techniques for a limited number of specific mutations included in the panel. Due to a variety of technical and biological limitations, however, such as allelic dropouts and the occurrence of de novo mutations, the detection rate is not 100%; there is always a residual risk that needs to be estimated and provided to individuals based on the existing knowledge on frequency of gene, penetrance of phenotype, and prevalence of condition in the general and specific ethnic populations.

Continue to: Expanded vs panethnic screening...


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