A re-examination of the use of ethnicity in prenatal carrier testing

Reproductive genetic carrier screening in pregnancy: improving health outcomes and expanding access

Reproductive genetic carrier screening (RGCS) serves to screen couples for their risk of having children affected by monogenic conditions. The included conditions are mostly autosomal recessive or X-linked with infantile or early-childhood onset. Cystic fibrosis, spinal muscular atrophy, and hemoglobinopathies are now recommended by the American College of Obstetricians and Gynecologists (ACOG) for universal screening. Recommendations for further RGCS remain ethnicity based. The American College of Medical Genetics and Genomics and the National Society of Genetic Counselors in recent years have recommended universal expanded-panel RGCS and moving towards a more equitable approach. ACOG guidelines state that offering RGCS is an acceptable option, however it has not provided clear guidance on standard of care. Positive results on RGCS can significantly impact reproductive plans for couples, including pursuing in vitro fertilization with preimplantation genetic testing, prenatal genetic testing, specific fetal or neonatal treatment, or adoption. RGCS is a superior approach compared to ethnicity-based carrier screening and moves away from single race-based medical practice. We urge the obstetrics and gynecology societies to adopt the guidelines for RGCS put forward by multiple societies and help reduce systemic inequalities in medicine in our new genetic age. Having national societies such as ACOG and the Society for Maternal-Fetal Medicine officially recommend and endorse RGCS would bolster insurance coverage and financial support by employers for RGCS. The future of comprehensive reproductive care in the age of genomic medicine entails expanding access so patients and families can make the reproductive options that best fit their needs.

Attitudes and beliefs regarding race-targeted genetic testing of Black people: A systematic review

Geographical ancestry has been associated with an increased risk of various genetic conditions. Race and ethnicity often have been used as proxies for geographical ancestry. Despite numerous problems associated with the crude reliance on race and ethnicity as proxies for geographical ancestry, some genetic testing in the clinical, research, and employment settings has been and continues to be race- or ethnicity-based. Race-based or race-targeted genetic testing refers to genetic testing offered only or primarily to people of particular racial or ethnic groups because of presumed differences among groups. One current example is APOL1 testing of Black kidney donors. Race-based genetic testing raises numerous ethical and policy questions. Given the ongoing reliance on the Black race in genetic testing, it is important to understand the views of people who identify as Black or are identified as Black (including African American, Afro-Caribbean, and Hispanic Black) regarding race-based genetic testing that targets Black people because of their race. We conducted a systematic review of studies and reports of stakeholder-engaged projects that examined how people who identify as or are identified as Black perceive genetic testing that specifically presumes genetic differences exist among racial groups or uses race as a surrogate for ancestral genetic variation and targets Black people. Our review identified 14 studies that explicitly studied this question and another 13 that implicitly or tacitly studied this matter. We found four main factors that contribute to a positive attitude toward race-targeted genetic testing (facilitators) and eight main factors that are associated with concerns regarding race-targeted genetic testing (barriers). This review fills an important gap. These findings should inform future genetic research and the policies and practices developed in clinical, research, public health, or other settings regarding genetic testing.

Challenges in providing residual risks in carrier testing

The probability an individual is a carrier for a recessive disorder despite a negative carrier test, referred to as residual risk, has been part of carrier screening for over 2 decades. Residual risks are calculated by subtracting the frequency of carriers of pathogenic variants detected by the test from the carrier frequency in a population, estimated from the incidence of the disease. Estimates of the incidence (and therefore carrier frequency) of many recessive disorders differ among different population groups and are inaccurate or unavailable for many genes on large carrier screening panels for most of the world's populations. The pathogenic variants detected by the test and their frequencies also vary across groups and over time as variants are newly discovered or reclassified, which requires today's residual carrier risks to be continually updated. Even when a residual carrier risk is derived using accurate data obtained in a particular group, it may not apply to many individuals in that group because of misattributed ancestry or unsuspected admixture. Missing or inaccurate data, the challenge of determining meaningful ancestry‐specific risks and applying them appropriately, and a lack of evidence they impact management, suggest that patients be counseled that although carrier screening may miss a small fraction of carriers, residual risks with contemporary carrier screening are well below the risk posed by invasive prenatal diagnosis, even if one member of the couple is a carrier, and that efforts to provide precise residual carrier risks are unnecessary.

What's already known about this topic? What does this study add?

There has been no published discussion of the methods and uncertainties involved in the calculation of residual risk that are discussed here

There has been much discussion of using ancestry in genetic testing but this review highlights the serious problems that arise in calculating and assigning ancestry‐specific residual carrier risks at specific disease loci

The review questions what has not been questioned before: Is there clinical utility to providing what are mostly imprecise residual carrier risks

Current landscape of prenatal genetic screening and testing

Pregnant patients should be offered the option of prenatal genetic screening and diagnostic testing. The type of screening and testing offered to a patient may depend on various factors including but not limited to age, family history, fetal findings, exposures, and patient preferences. Prenatal screening is available for a variety of genetic conditions including aneuploidy, congenital abnormalities, and carrier status. Diagnostic testing options include karyotype, prenatal microarray, as well as next-generation sequencing. The various options differ in methodology, accuracy, timing and indication for testing, and information they provide. Given that the technologies related to prenatal testing are rapidly evolving and improving, the array of available screening and testing modalities are increasing. This article reviews the current offerings in prenatal screening and diagnosis.

Expanded carrier screening: A review of early implementation and literature

Carrier screening is the practice of testing individuals to identify those at increased risks of having children affected by genetic diseases. Professional guidelines on carrier screening have been available for more than 15 years, and have historically targeted specific diseases that occur at increased frequencies in defined ethnic populations. Enabled by rapidly evolving technology, expanded carrier screening aims to identify carriers for a broader array of diseases and may be applied universally (equally across all ethnic groups). This new approach deviates from the well-established criteria for screening models. In this review, we summarize the rationale for expanded carrier screening using available literature regarding clinical and technical data, as well as provider perspectives. We also discuss important avenues for further research in this burgeoning field.

Changing trends in carrier screening for genetic disease in the United States

Genetic disease is the leading cause of infant death in the United States, accounting for approximately 20% of annual infant mortality. Advances in genomic medicine and technological platforms have made possible low cost, pan-ethnic expanded genetic screening that enables obstetric care providers to offer screening for over 100 recessive genetic diseases. However, the rapid integration of genomic medicine into routine obstetric practice has raised some concerns about the practical implementation of such testing. These changing trends in carrier screening, along with concerns and potential solutions, will be addressed.

Comparison of Informed Consent Preferences for Multiplex Genetic Carrier Screening among a Diverse Population

Multiplex genetic carrier screening is increasingly being integrated into reproductive care. Obtaining informed consent becomes more challenging as the number of screened conditions increases. Implementing a model of generic informed consent may facilitate informed decision-making. Current Wayne State University students and staff were invited to complete a web-based survey by blast email solicitation. Participants were asked to determine which of two generic informed consent scenarios they preferred: a brief versus a detailed consent. They were asked to rank the importance of different informational components in making an informed decision and to provide demographic information. Comparisons between informational preferences, demographic variables and scenario preferences were made. Six hundred ninety three participants completed the survey. When evaluating these generic consents, the majority preferred the more detailed consent (74.5%), and agreed that it provided enough information to make an informed decision (89.5%). Those who thought it would be more important to know the severity of the conditions being screened (p = .002) and range of symptoms (p = .000) were more likely to prefer the more detailed consent. There were no significant associations between scenario preferences and demographic variables. A generic consent was perceived to provide sufficient information for informed decision making regarding multiplex carrier screening with most preferring a more detailed version of the consent. Individual attitudes rather than demographic variables influenced preferences regarding the amount of information that should be included in the generic consent. The findings have implications for how clinicians approach providing tailored informed consent.

Self-reported race/ethnicity in the age of genomic research: its potential impact on understanding health disparities

This review explores the limitations of self-reported race, ethnicity, and genetic ancestry in biomedical research. Various terminologies are used to classify human differences in genomic research including race, ethnicity, and ancestry. Although race and ethnicity are related, race refers to a person's physical appearance, such as skin color and eye color. Ethnicity, on the other hand, refers to communality in cultural heritage, language, social practice, traditions, and geopolitical factors. Genetic ancestry inferred using ancestry informative markers (AIMs) is based on genetic/genomic data. Phenotype-based race/ethnicity information and data computed using AIMs often disagree. For example, self-reporting African Americans can have drastically different levels of African or European ancestry. Genetic analysis of individual ancestry shows that some self-identified African Americans have up to 99% of European ancestry, whereas some self-identified European Americans have substantial admixture from African ancestry. Similarly, African ancestry in the Latino population varies between 3% in Mexican Americans to 16% in Puerto Ricans. The implication of this is that, in African American or Latino populations, self-reported ancestry may not be as accurate as direct assessment of individual genomic information in predicting treatment outcomes. To better understand human genetic variation in the context of health disparities, we suggest using "ancestry" (or biogeographical ancestry) to describe actual genetic variation, "race" to describe health disparity in societies characterized by racial categories, and "ethnicity" to describe traditions, lifestyle, diet, and values. We also suggest using ancestry informative markers for precise characterization of individuals' biological ancestry. Understanding the sources of human genetic variation and the causes of health disparities could lead to interventions that would improve the health of all individuals.

Development and performance of a comprehensive targeted sequencing assay for pan-ethnic screening of carrier status

Identifying individuals as carriers of severe disease traits enables informed decision making about reproductive options. Although carrier screening has traditionally been based on ethnicity, the increasing ethnic admixture in the general population argues for the need for pan-ethnic carrier screening assays. Highly multiplexed mutation panels allow for rapid and efficient testing of hundreds of mutations concurrently. We report the development of the Pan-Ethnic Carrier Screening assay, a targeted sequencing assay for routine screening that simultaneously detects 461 common mutations in 91 different genes underlying severe, early-onset monogenic disorders. Mutation selection was aided by the use of an extensive mutation database from a clinical laboratory with expertise in newborn screening and lysosomal storage disease testing. The assay is based on the Affymetrix GeneChip microarray platform but generates genomic DNA sequence as the output. Analytical sensitivity and specificity, using genomic DNA from archived control cultures and from clinical specimens, was found to be >99% for all mutation types. This targeted sequencing assay has advantages over multiplex PCR and next-generation sequencing assays, including accuracy of mutation detection over a range of mutation types and ease of analysis and reporting of results.