Purpose:Recent developments in genomics have led to expanded carrier screening panels capable of assessing hundreds of causal mutations for genetic disease. This new technology enables simultaneous measurement of carrier frequencies for many diseases. As the resultant rank-ordering of carrier frequencies impacts the design and prioritization of screening programs, the accuracy of this ranking is a public health concern.Methods:A total of 23,453 individuals from many obstetric, genetics, and infertility clinics were referred for routine recessive disease carrier screening. Multiplex carrier screening was performed and results were aggregated for this study.Results:Twenty-four percent of individuals were identified as carriers for at least one of 108 disorders, and 5.2% were carriers for multiple disorders. We report tabulations of carrier frequency by self-identified ethnicity and disease.Conclusion:To our knowledge, this study of a large, ethnically diverse clinical sample provides the most accurate measurements to date of carrier frequencies for hundreds of recessive alleles. The study also yields information on the clinical considerations associated with routine use of expanded panels and provides support for a pan-ethnic screening paradigm that minimizes the use of “racial” categories by the physician, as recommended by recent guidelines.

IMPORTANCE Screening for carrier status of a limited number of single-gene conditions is the current standard of prenatal care. Methods have become available allowing rapid expanded carrier screening for a substantial number of conditions. OBJECTIVES To quantify the modeled risk of recessive conditions identifiable by an expanded carrier screening panel in individuals of diverse racial and ethnic backgrounds and to compare the results with those from current screening recommendations. DESIGN, SETTING, AND PARTICIPANTS Retrospective modeling analysis of results between January 1, 2012, and July 15, 2015, from expanded carrier screening in reproductive-aged individuals without known indication for specific genetic testing, primarily from the United States. Tests were offered by clinicians providing reproductive care. EXPOSURES Individuals were tested for carrier status for up to 94 severe or profound conditions. MAIN OUTCOMES AND MEASURES Risk was defined as the probability that a hypothetical fetus created from a random pairing of individuals (within or across 15 self-reported racial/ethnic categories; there were 11 categories with >5000 samples) would be homozygous or compound heterozygous for 2 mutations presumed to cause severe or profound disease. Severe conditions were defined as those that if left untreated cause intellectual disability or a substantially shortened lifespan; profound conditions were those causing both. RESULTS The study included 346 790 individuals. Among major US racial/ethnic categories, the calculated frequency of fetuses potentially affected by a profound or severe condition ranged from 94.5 per 100 000 (95% CI, 82.4-108.3 per 100 000) for Hispanic couples to 392.2 per 100 000 (95% CI, 366.3-420.2 per 100 000) for Ashkenazi Jewish couples. In most racial/ethnic categories, expanded carrier screening modeled more hypothetical fetuses at risk for severe or profound conditions than did screening based on current professional guidelines (Mann-Whitney P < .001). For Northern European couples, the 2 professional guidelines-based screening panels modeled 55.2 hypothetical fetuses affected per 100 000 (95% CI, 51.3-59.3 per 100 000) and the expanded carrier screening modeled 159.2 fetuses per 100 000 (95% CI, 150.4-168.6 per 100 000). Overall, relative to expanded carrier screening, guideline-based screening ranged from identification of 6% (95% CI, 4%-8%) of hypothetical fetuses affected for East Asian couples to 87% (95% CI, 84%-90%) for African or African American couples. CONCLUSIONS AND RELEVANCE In a population of diverse races and ethnicities, expanded carrier screening may increase the detection of carrier status for a variety of potentially serious genetic conditions compared with current recommendations from professional societies. Prospective studies comparing current standard-of-care carrier screening with expanded carrier screening in at-risk populations are warranted before expanded screening is adopted.

Professional guidelines dictate that disease severity is a key criterion for carrier screening. Expanded carrier screening, which tests for hundreds to thousands of mutations simultaneously, requires an objective, systematic means of describing a given disease's severity to build screening panels. We hypothesized that diseases with characteristics deemed to be of highest impact would likewise be rated as most severe, and diseases with characteristics of lower impact would be rated as less severe. We describe a pilot test of this hypothesis in which we surveyed 192 health care professionals to determine the impact of specific disease phenotypic characteristics on perceived severity, and asked the same group to rate the severity of selected inherited diseases. The results support the hypothesis: we identified four “Tiers” of disease characteristics (1–4). Based on these responses, we developed an algorithm that, based on the combination of characteristics normally seen in an affected individual, classifies the disease as Profound, Severe, Moderate, or Mild. This algorithm allows simple classification of disease severity that is replicable and not labor intensive.

(Abstracted from JAMA 2016;316(7):734–742) As part of routine obstetrical practice, many prospective parents undergo genetic testing to detect carriers of specific inherited recessive diseases. There are recommendations provided by professional organizations to test for a limited number of individual diseases that are in part based on self-reported racial/ethnic backgrounds.

Expanded carrier screening (ECS) analyzes dozens or hundreds of recessive genes to determine reproductive risk. Data on the clinical utility of screening conditions beyond professional guidelines are scarce. Individuals underwent ECS for up to 110 genes. Five-hundred thirty-seven at-risk couples (ARC), those in which both partners carry the same recessive disease, were invited to participate in a retrospective IRB-approved survey of their reproductive decision making after receiving ECS results. Sixty-four eligible ARC completed the survey. Of 45 respondents screened preconceptionally, 62% (n = 28) planned IVF with PGD or prenatal diagnosis (PNDx) in future pregnancies. Twenty-nine percent (n = 13) were not planning to alter reproductive decisions. The remaining 9% (n = 4) of responses were unclear. Of 19 pregnant respondents, 42% (n = 8) elected PNDx, 11% (n = 2) planned amniocentesis but miscarried, and 47% (n = 9) considered the condition insufficiently severe to warrant invasive testing. Of the 8 pregnancies that underwent PNDx, 5 were unaffected and 3 were affected. Two of 3 affected pregnancies were terminated. Disease severity was found to have significant association (p = 0.000145) with changes in decision making, whereas guideline status of diseases, controlled for severity, was not (p = 0.284). Most ARC altered reproductive planning, demonstrating the clinical utility of ECS. Severity of conditions factored into decision making.Electronic supplementary materialThe online version of this article (10.1007/s10897-017-0160-1) contains supplementary material, which is available to authorized users.

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. © 2015 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.

Purpose: The recent growth in pan-ethnic expanded carrier screening (ECS) has raised questions about how such panels might be designed and evaluated systematically. Design principles for ECS panels might improve clinical detection of at-risk couples and facilitate objective discussions of panel choice.Methods: Guided by medical-society statements, we propose a method for the design of ECS panels that aims to maximize the aggregate and per-disease sensitivity and specificity across a range of Mendelian disorders considered serious by a systematic classification scheme. We evaluated this method retrospectively using results from 474,644 de-identified carrier screens. We then constructed several idealized panels to highlight strengths and limitations of different ECS methodologies.Results: Based on modeled fetal risks for "severe" and "profound" diseases, a commercially available ECS panel (Counsyl) is expected to detect 183 affected conceptuses per 100,000 US births. A screen's sensitivity is greatly impacted by two factors: (i) the methodology used (e.g., full-exon sequencing finds more affected conceptuses than targeted genotyping) and (ii) the detection rate of the screen for diseases with high prevalence and complex molecular genetics (e.g., fragile X syndrome). Conclusion:The described approaches enable principled, quantitative evaluation of which diseases and methodologies are appropriate for pan-ethnic expanded carrier screening.

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.