Ethnically unique disease burden and limitations of current expanded carrier screening panels

OBJECTIVES

The purpose of the study is to identify the recessive diseases currently affecting real-world pediatric patients in Taiwan, and whether current extended carrier screening panels have the coverage and detective power to identify the pathogenic variants in the carrier parents.

METHODS

A total of 132 trio-samples were collected from May 2017 to March 2022. The participants were parents of pediatric intensive care unit patients who were critically ill or infants with abnormal newborn screening results. A retrospective carrier screening scheme was applied to analyze only the carrier status of pathogenic or likely pathogenic recessive variants resulting in diseases in their children. The recessive disorders diagnosed in our cohort were compared with the gene content in commercial panels.

RESULTS

Mutations in COQ4, PEX1, OTC, and IKBKG were the most frequently identified. In the parents of 44 children with confirmed diagnoses of recessive diseases, 47 (53.40%) screened positive for being the carriers of the same recessive disorders diagnosed in their children. The commercial panels covered 35.13% to 54.05% of the disorders diagnosed in this cohort.

CONCLUSION

Clinicians and genetic counselors should be aware of the limitations of current extended carrier screening and interpret negative screening results with caution. Future panels should also consider genes with ethnically unique mutations such as pathogenic variants of the COQ4 gene in the East Asian population.

Determining the right "dose" of genetic testing for gamete donors

IMPORTANCE

Genetic testing of gamete donors is becoming increasingly comprehensive and now often includes expanded carrier screening. Some argue that testing has gone too far, whereas others propose that testing is not extensive enough. Thinking critically about how much genetic testing is appropriate for gamete donors is crucial for ensuring that market forces alone do not determine the level of testing that is performed.

OBJECTIVE

The goal of this paper is to highlight contradictions in the current approach toward genetic testing of gamete donors and to suggest that we either embrace the value of preventing the birth of children with hereditary diseases and do so in a logical and consistent manner or consider reducing our level of genetic testing for gamete donors.

EVIDENCE REVIEW

The Food and Drug Administration requires screening for infectious diseases and the American Society for Reproductive Medicine recommends screening for a small number of common recessive conditions. However, private donor banks are increasingly performing karyotype testing and expanded carrier screening.

FINDINGS

There are 2 major inconsistencies in our current approach to genetic testing of gamete donors: (1) if genetic information is valued by gamete recipients, why should testing stop with recessive conditions, and not expand to dominant conditions or even polygenic risk scoring? (2) Why should gamete donors be asked to undergo testing that may or may not be reciprocated by gamete recipients? Addressing these inconsistencies requires us to consider the ultimate goal of testing gamete donors' genes. We argue that the present, default goal is empowerment of gamete recipients, whereas an alternative and more laudable mission is to avoid preventable, heritable disease in offspring. However, the latter brings its own ethical and practical challenges, including the issue of which diseases are worth preventing.

CONCLUSION AND RELEVANCE

A more comprehensive and well-reasoned approach to genetic testing of gamete donors is needed. Otherwise, testing will continue to be haphazard and guided by the free market, rather than deeper societal values.

The Potential Usefulness of the Expanded Carrier Screening to Identify Hereditary Genetic Diseases: A Case Report from Real-World Data

Expanded carrier screening (ECS) means a comprehensive genetic analysis to evaluate an individual's carrier status. ECS is becoming more frequently used, thanks to the availability of techniques such as next generation sequencing (NGS) and array comparative genomic hybridization (aCGH), allowing for extensive genome-scale analyses. Here, we report the case of a couple who underwent ECS for a case of autism spectrum disorder in the male partner family. aCGH and whole-exome sequencing (WES) were performed in the couple. aCGH analysis identified in the female partner two deletions involving genes associated to behavioral and neurodevelopment disorders. No clinically relevant alterations were identified in the husband. Interestingly, WES analysis identified in the male partner a pathogenic variant in the LPL gene that is emerging as a novel candidate gene for autism. This case shows that ECS may be useful in clinical contexts, especially when both the partners are analyzed before conception, thus allowing the estimation of their risk to transmit an inherited condition. On the other side, there are several concerns related to possible incidental findings and difficult-to-interpret results. Once these limits are defined by the establishment of specific guidelines, ECS may have a greater diffusion.

The influence of expanded carrier screening in assisted reproductive techniques: changed the 'game'- review

Expanded carrier screening constitutes a new scientific tool able to detect conditions that can be treated immediately after birth or during pregnancy. Its implementation could affect both the prenatal period and assisted reproductive techniques. It is strongly beneficial as it provides much useful information to future parents concerning the medical status of their offspring. In addition, the definition of 'serious/severe', regulating preimplantation diagnosis, donor insemination, and even the definitions of prerequisites for abortion diseases, should be reformed including all clinically severe diseases. On the other hand, controversies may arise especially regarding gamete donation. Future parents and offspring maybe informed regarding donors' demographic and medical characteristics. This study aims to investigate the effects of the implementation of expanded carrier screening in the reformation of the definition of 'severe/serious' disease, the decision-making of future parents, gamete donation, and the possible new moral dilemmas that may arise.

Clinical utility of reproductive carrier screening for preconception and pregnant couples for multiple genetic conditions: a systematic review and meta-analysis

INTRODUCTION

Many scientific societies have emphasized the importance of evaluating the clinical utility of reproductive carrier screening (RCS). This systematic review aims to assess the clinical utility of RCS and synthesize the outcomes in a meta-analysis.

AREAS COVERED

A total of eleven studies were included. The number of conditions screened in the studies varied from three to 176 and led to the identification of one to 24 high-risk couples (HRCs) per 1,000 screened individuals. Pooled estimations were as follows: the prenatal diagnosis (PND) rate among pregnant HRCs 0.644 (95% CI=0.364, 0.923), the termination rate among affected pregnancies 0.714 (95% CI=0.524, 0.904), and the rate of in-vitro fertilization (IVF) with preimplantation genetic testing (PGT) 0.631 (95% CI=0.538, 0.725). There is a statistically significant decrease in the rates of undertaking PND and termination as the number of screened conditions increases. Carriers of conditions classified as having a more severe impact were found to be more likely to choose termination or IVF with PGT.

EXPERT OPINION

Our review suggests that the number and the severity of screened conditions can significantly impact HRCs' reproductive decisions. Future work needs to investigate the definition of clinical utility and the design of screening panels.

Pregnant Latinas' perspectives on pursuing expanded carrier screening: "It is better to know than not"

With the advance of genetic technologies, the use of expanded carrier screening (ECS) in the prenatal setting is growing. ECS tests for a wide range of inherited genetic disorders regardless of racial/ethnic background and family history. Latinxs are an important ECS stakeholder group as they are the largest minority group with the highest fertility rate in the United States. Yet, the Latinx population has, to date, been underrepresented and understudied in genetics/genomics research. We conducted a study to explore the knowledge and perspectives of pregnant Latinas regarding ECS in which descriptive statistics and content analysis were used to analyze the data. Thirty-two pregnant Latinas - mostly of low educational levels (no education beyond high school) and with less than $20,000 annual household income living in rural areas were surveyed, provided with education about ECS, and interviewed. Participants were found to possess limited knowledge about ECS prior to being interviewed. Most (68.8%), however, expressed interest in pursuing ECS following the educational component that explained ECS. Their interest was mainly driven by the desire to know their baby's chance of developing a genetic disorder, the low risk of ECS procedures for both pregnant Latinas and their fetus, and the opportunity to better prepare for raising a child with a genetic condition. Our findings contribute to the limited research in the genetics/genomics field by providing in-depth insights into the perspectives of pregnant Latinas regarding ECS. Obstetric providers and genetic counselors should provide culturally appropriate education and counseling to empower pregnant Latinas to make informed decisions about the use of ECS.

Primary care professionals' views on population-based expanded carrier screening: an online focus group study

BACKGROUND

Population-based expanded carrier screening (ECS) involves screening for multiple recessive diseases offered to all couples considering a pregnancy or during pregnancy. Previous research indicates that in some countries primary care professionals are perceived as suitable providers for ECS. However, little is known about their perspectives. We therefore aimed to explore primary care professionals' views on population-based ECS.

METHODS

Four online focus groups with 14 general practitioners (GPs) and 16 community midwives were conducted in the Netherlands.

RESULTS

Our findings highlight various perspectives on the desirability of population-based ECS. Participants agreed that ECS could enhance reproductive autonomy and thereby prevent suffering of the child and/or parents. However, they also raised several ethical, societal, and psychological concerns, including a tendency towards a perfect society, stigmatization, unequal access to screening and negative psychosocial consequences. Participants believed that provision of population-based ECS would be feasible if prerequisites regarding training and reimbursement for providers would be fulfilled. most GPs considered themselves less suitable or capable of providing ECS, in contrast to midwives who did consider themselves suitable. Nevertheless, participants believed that, if implemented, ECS should be offered in primary care or by public health services rather than as hospital-based specialized care, because they believed a primary care ECS offer increases access in terms of time and location.

CONCLUSIONS

While participants believed that an ECS offer would be feasible, they questioned its desirability and priority. Studies on the desirability and feasibility of population-based ECS offered in primary care or public health settings are needed.

General infertility workup in times of high assisted reproductive technology efficacy

The assessments of oocyte quality and quantity and endocrine profile have traditionally been the cornerstone of the general workup of couples with infertility. Over the years, several clinical, hormonal, and functional biomarkers have been adopted to assess ovarian function and identify endocrine disorders before assisted reproductive technology. Furthermore, the genetic workup of patients has drastically changed, introducing novel markers. This not only allowed the prediction of response to ovarian stimulation but also contributed toward the development of a safer and more efficient management of women undergoing assisted reproductive technology. The scope of this review is to provide an overview of the current and novel strategies adopted for the assessment of ovarian function and ovulatory and endocrine disorders in women planning to conceive. Furthermore, it aims to provide an insight in the role of novel genetic biomarkers and use of expanded carrier screening as part of preliminary workup of women with infertility.

Expanded carrier screening in the United States: A systematic evidence review exploring client and provider experiences

The aim of carrier screening is to identify prospective parents at risk of having a pregnancy affected with an autosomal recessive or X-linked disorder. Though minimal guideline-based screening is available, expanded carrier screening (ECS) is quickly becoming a feasible option for the general population due to its growing availability and affordability. However, the impact of ECS on clients and providers remains relatively unexplored. We performed a systematic evidence review to identify publications describing client-, provider-, and test-related outcomes. We searched several biomedical databases for articles published between January 1, 2003 and May 31, 2021. Studies were eligible for inclusion if they described genetic counseling and/or genetic testing for carrier screening (minimal guideline-based or ECS) in a prenatal or preconception setting in the United States. Title and abstract screening were performed using the Raayan web application or customized Google Forms. Full-text review and data extraction of included articles were performed using custom Google Forms. Two researchers performed a multistep selection process independently for validation purposes. Of 5413 unique articles screened, 36 studies were included with several studies contributing to multiple outcomes. Twenty described outcomes relating to patients/clients, 10 described provider-based outcomes, and 16 described test-based outcomes. Findings suggest that client and provider perceptions of ECS and minimal guideline-based carrier screening are multifaceted. Though clients have expressed desire for ECS, clinical uptake and impact on reproductive decision-making varies. Additionally, though genetic counselors seem to be comfortable with ECS, most other reproductive care providers seem to prefer minimal guideline or ancestry-based screening due to perceived barriers, such as time needed for ECS results disclosure and follow-up, as well as the desire to have panels set by professional societies/recommendations. There are limitations within the gathered literature, leading to potential uncertainty in the generalizability of our review. We outline several recommendations for future studies, including the need to examine variant interpretation and use of next-generation sequencing.

Clinical validity and utility of preconception expanded carrier screening for the management of reproductive genetic risk in IVF and general population

STUDY QUESTION

What is the clinical validity and utility of preconception Expanded Carrier Screening (ECS) application on the management of prospective parents?

SUMMARY ANSWER

The high detection rate of at-risk couples (ARCs) and the high proportion opting for IVF/preimplantation genetic testing (PGT) treatment demonstrate the clinical utility of ECS in the preconception space in IVF and general population.

WHAT IS KNOWN ALREADY

About 2-4% of couples are at risk of conceiving a child with an autosomal recessive or X-linked genetic disorder. In recent years, the increasing cost-effectiveness of genetic diagnostic techniques has allowed the creation of ECS panels for the simultaneous detection of multiple recessive disorders. Comprehensive preconception genetic screening holds the potential to significantly improve couple's genetic risk assessment and reproductive planning to avoid detectable inheritable genetic offspring.

STUDY DESIGN, SIZE, DURATION

A total of 3877 individuals without a family history of genetic conditions were analyzed between January 2017 and January 2020. Of the enrolled individuals, 1212 were gamete donors and 2665 were patients planning on conceiving from both the IVF and the natural conception group. From the non-donor cohort, 1133 were analyzed as individual patients, while the remaining ones were analyzed as couples, for a total of 766 couples.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A focused ECS panel was developed following American College of Obstetrics and Gynecology ACOG-recommended criteria (prevalence, carrier rate, severity), including highly penetrant severe childhood conditions. Couples were defined at-risk when both partners carried an autosomal recessive pathogenic/likely pathogenic variant (PLP) on the same gene or when the woman was a carrier of an X-linked PLP variant. ARC detection rate defined the clinical validity of the ECS approach. Clinical utility was evaluated by monitoring ARCs reproductive decision making.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 402 individuals (10.4%) showed PLP for at least one of the genes tested. Among the 766 couples tested, 173 showed one carrier partner (22.6%), whereas 20 couples (2.6%) were found to be at increased risk. Interestingly, one ARC was identified as a result of cascade testing in the extended family of an individual carrying a pathogenic variant on the Survival Of Motor Neuron 1SMN1 gene. Of the identified ARCs, 5 (0.7%) were at risk for cystic fibrosis, 5 (0.7%) for fragile X syndrome, 4 (0.5%) for spinal muscular atrophy, 4 (0.5%) for Beta-Thalassemia/Sickle Cell Anemia, 1 (0.1%) for Smith-Lemli-Opitz Syndrome and 1 (0.1%) for Duchenne/Becker Dystrophy. Fifteen ARCs were successfully followed up from both the IVF and the natural conception groups. All of these (15/15) modified their reproductive planning by undergoing ART with Preimplantation Genetic Testing for Monogenic disease and Aneuploidies (PGT-M and PGT-A). To date, 6/15 (40%) couples completed their PGT cycle with euploid/unaffected embryos achieving a pregnancy after embryo transfer and three of them have already had an unaffected baby.

LIMITATIONS, REASONS FOR CAUTION

The use of a limited panel of core gene-disease pairs represents a limitation on the research perspective as it can underestimate the rate of detectable carriers and ARCs in this cohort of prospective parents. Expanding the scope of ECS to a larger panel of conditions is becoming increasingly feasible, thanks to a persistent technological evolution and progressive cataloging of gene-disease associations.

WIDER IMPLICATIONS OF THE FINDINGS

These results highlight the potential clinical validity and utility of ECS in reducing the risk of a pregnancy affected by a detectable inheritable genetic condition. The steady reduction in the costs of genetic analyses enables the expansion of monogenic testing/screening applications at the preimplantation stage, thus, providing valid decisional support and reproductive autonomy to patients, particularly in the context of IVF.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. A.C., M.F., S.C., M.P., L.G., and C.P. are employees of Igenomix Italy. C.S. is the head of the scientific board of Igenomix.

TRIAL REGISTRATION NUMBER

N/A.

Expanded carrier screening in Flanders (Belgium): an online survey on the perspectives of nonpregnant reproductive-aged women

Aim: Despite a considerable interest in expanded carrier screening (ECS) in the general population, actual uptake of ECS remains low. More insights are needed to better understand the perspectives of reproductive-aged individuals. Materials & methods: Nonpregnant women of reproductive age recruited through public pharmacies throughout Flanders (Belgium) were invited to participate in an online survey. Results: Most participants (63.6%) indicated they would consider ECS for themselves in the future. About one in two participants showed a positive attitude toward ECS. Conclusion: This study reports valuable insights in the perspectives of nonpregnant reproductive-aged women in Flanders (Belgium) regarding ECS that can be used in the ongoing debate on the responsible implementation of ECS.

The use of expanded carrier screening of gamete donors

STUDY QUESTION

What are the sperm and egg donor rejection rates after expanded carrier screening (ECS)?

SUMMARY ANSWER

Using an ECS panel looking at 46/47 genes, 17.6% of donors were rejected.

WHAT IS KNOWN ALREADY

The use of ECS is becoming commonplace in assisted reproductive technology, including testing of egg and sperm donors. Most national guidelines recommend rejection of donors if they are carriers of a genetic disease. If the use of ECS increases, there will be a decline in the number of donors available.

STUDY DESIGN, SIZE, DURATION

A review of the current preconception ECS panels available to donors was carried out through an online search. The genetic testing results of donors from Cryos International were analysed to determine how many were rejected on the basis of the ECS.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data on gamete donors and their carrier status was provided by Cryos International, who screen donors using their own bespoke ECS panel. The ECS panels identified through the review were compared to the Cryos International panel and data.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 16 companies and 42 associated ECS panels were reviewed. There were a total of 2673 unique disorders covered by the panels examined, with a mean of 329 disorders screened. None of these disorders were common to all panels. Cryos International screen 46 disorders in males and 47 in females. From 883 candidate donors, 17.6% (155/883) were rejected based on their ECS result. Carriers of alpha-thalassaemia represented the largest proportion of those rejected (19.4%, 30/155), then spinal muscular atrophy (15.5%, 24/155) and cystic fibrosis (14.8%, 23/155).

LIMITATIONS, REASONS FOR CAUTION

Panel information was found on company websites and may not have been accurate.

WIDER IMPLICATIONS OF THE FINDINGS

This study highlights the need for consistent EU regulations and guidelines that allow genetic matching of gamete donors to their recipients, preventing the need to reject donors who are known carriers. A larger ECS panel would be most beneficial; however, this would not be viable without matching of donors and recipients.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was obtained. J.C.H. is the founder of Global Women Connected, a platform to discuss women's health issues and the Embryology and PGD Academy, who deliver education in clinical embryology. She has been paid to give a lecture by Cryos in 2019. A-B.S. is an employee of Cryos International.

TRIAL REGISTRATION NUMBER

N/A.

Expanded carrier screening should not be mandatory for gamete donors

More and more centers are imposing expanded carrier screening (ECS) on their gamete donors. In some clinics and gamete banks, gamete donors are not given this right, contrary to the freedom to decline genetic screening in the general population. The possible social and psychological burdens that are recognized for infertility patients and the general population are downplayed for gamete donors. The procedure of imposing ECS on gamete donors shows that the interests of the recipients are valued higher than those of the donors. The general ethical argument defended here is the principle of proportionality: the burdens imposed on donors have to be balanced against the potential benefits for the offspring and the recipients. The risk reduction of ECS is below 1% and is too small to outweigh the potential dangers and disadvantages for donors. The conclusion is that clinics may ask, but not compel, donors to submit to ECS provided that they offer appropriate genetic and psychological counseling.

Preconception expanded carrier screening: Impact of information presented by text or video on genetic knowledge and attitudes

Preconception expanded carrier screening (ECS) aims to identify couples with an increased risk of having a child with an autosomal recessive (AR) disorder before pregnancy, thereby enabling reproductive choices. Genetic knowledge and experiential knowledge both influence the uptake of ECS. As people in the general public often lack such knowledge, it is essential to provide appropriate and understandable information when offering ECS. This study investigated the effect of an educational video, compared to an educational text, on the knowledge and attitudes toward preconception ECS in the general population. Both the text and video consisted of a brief educational summary on AR inheritance and on the type of disorders included in ECS, with the progressive neurodegenerative condition mucopolysaccharidosis type III (MPS III) as an example. Participants in the reproductive age were invited in collaboration with a research agency. Respondents (N = 789) were offered an educational video prior to completing an online questionnaire that examined genetic knowledge, the perceived severity of MPS III, perceived risk, and attitudes toward ECS. Outcomes were compared to reference data collected previously in which respondents had been offered an educational text (N = 781). We first again studied the attitudes toward ECS in a smaller educational text group (N = 266) in order to assess whether attitudes had changed over time due to increased media coverage on ECS, which did not reveal any significant changes. Respondents who were offered the video had a better genetic knowledge, perceived MPS III as more severe, perceived their risks higher and were more likely to participate in ECS compared to those who were offered text. Online video may well be used as supportive tool to the genetic counseling process, creating more knowledge on ECS and severe genetic disorders included in preconception screening panels.

Clinical Implementation of Expanded Carrier Screening in Pregnant Women at Early Gestational Weeks: A Chinese Cohort Study

Demands for expanded carrier screening (ECS) are growing and ECS is becoming an important part of obstetrics practice and reproductive planning. The aim of this study is to evaluate the feasibility of a small-size ECS panel in clinical implementation and investigate Chinese couples’ attitudes towards ECS. An ECS panel containing 11 recessive conditions was offered to Chinese pregnant women below 16 gestational weeks. Sequential testing of their partners was recommended for women with a positive carrier status. The reproductive decision and pregnancy outcome were surveyed for at-risk couples. A total of 1321 women performed ECS successfully and the overall carrier rate was 19.23%. The estimated at-risk couple rate was 0.83%. Sequential testing was performed in less than half of male partners. Eight at-risk couples were identified and four of them performed prenatal diagnosis. Our study demonstrated that a small-size ECS panel could yield comparable clinical value to a larger-size panel when the carrier rate of the individual condition is equal or greater than 1%. In addition, more than half of male partners whose wives were carriers declined any types of sequential testing possibly due to a lack of awareness and knowledge of genetic disorders. Genetic education is warranted for the better implementation of ECS.

Considerations of expanded carrier screening: Lessons learned from combined malonic and methylmalonic aciduria

Background

Expanded carrier screening (ECS) utilizes high‐throughput next‐generation sequencing to evaluate an individual's carrier status for multiple conditions. Combined malonic and methylmalonic aciduria (CMAMMA) due to ACSF3 deficiency is a rare inherited disease included in such screening panels. Some cases have been reported with metabolic symptoms in childhood yet other cases describe a benign clinical course, suggesting the clinical phenotype is not well defined.

Methods/Case Report

Clinical and laboratory findings during the prenatal period were obtained retrospectively from medical records.

Results

A 37‐year‐old nulliparous woman and her partner were each identified as carriers of ACSF3 variants and presented at 9 weeks gestation for prenatal genetic consultation. The couple received extensive genetic counseling and proceeded with chorionic villus sampling at 11 weeks gestation. Subsequent analysis confirmed that the fetus inherited both parental ACSF variants. The couple was devastated by the results and after reviewing options of pregnancy continuation and termination, they decided to terminate the pregnancy. Following this decision, the patient was diagnosed with acute stress disorder.

Conclusion

This case highlights how expanded carrier screening adds complexity to reproductive decision‐making. Stronger guidelines and additional research are needed to direct and evaluate the timing, composition, and implementation of ECS panels.

The ethics of preconception expanded carrier screening in patients seeking assisted reproduction

Expanded carrier screening (ECS) entails a screening offer for carrier status for multiple recessive disorders simultaneously and allows testing of couples or individuals regardless of ancestry or geographic origin. Although universal ECS—referring to a screening offer for the general population—has generated considerable ethical debate, little attention has been given to the ethics of preconception ECS for patients applying for assisted reproduction using their own gametes. There are several reasons why it is time for a systematic reflection on this practice. Firstly, various European fertility clinics already offer preconception ECS on a routine basis, and others are considering such a screening offer. Professionals involved in assisted reproduction have indicated a need for ethical guidance for ECS. Secondly, it is expected that patients seeking assisted reproduction will be particularly interested in preconception ECS, as they are already undertaking the physical, emotional and economic burdens of such reproduction. Thirdly, an offer of preconception ECS to patients seeking assisted reproduction raises particular ethical questions that do not arise in the context of universal ECS: the professional’s involvement in the conception implies that both parental and professional responsibilities should be taken into account. This paper reflects on and provides ethical guidance for a responsible implementation of preconception ECS to patients seeking assisted reproduction using their own gametes by assessing the proportionality of such a screening offer: do the possible benefits clearly outweigh the possible harms and disadvantages? If so, for what kinds of disorders and under what conditions?

Expanded Carrier Screening in Chinese Population - A Survey on Views and Acceptance of Pregnant and Non-Pregnant Women

Objective

Recessive genetic diseases impose physical and psychological impacts to both newborns and parents who may not be aware of being carriers. Expanded carrier screening (ECS) allows screening for multiple genetic conditions at the same time. Whether or not such non-targeted panethnic approach of genetic carrier screening should replace the conventional targeted approach remains controversial. There is limited data on view and acceptance of ECS in general population, as well as the optimal timing of offering ECS to women. This study assesses views and acceptance of ECS in both pregnant women and non-pregnant women seeking fertility counseling or checkup and their reasons for accepting or declining ECS.

Materials and methods

This is a questionnaire survey with ECS information in the form of pamphlets distributed from December 2016 to end of 2018. Women were recruited from the antenatal clinics and the assisted reproductive unit at the Department of Obstetrics and Gynaecology, Queen Mary Hospital and the prepregnancy counseling clinic at the Family Planning Association of Hong Kong.

Results

A total of 923 women were recruited: 623 pregnant women and 300 non-pregnant women. There were significantly more non-pregnant women accepting ECS compared to pregnant women (70.7% vs. 61.2%). Eight hundred and sixty-eight (94%) women perceived ECS as at least as effective as or superior to traditional targeted screening. Significantly more pregnant women have heard about ECS compared with non-pregnant women (42.4% vs. 32.3%, P = 0.0197). Majority of women showed lack of understanding about ECS despite reading pamphlets that were given to them prior to filling in the questionnaires. Cost of ECS was a major reason for declining ECS, 28% (n = 256). Significantly more pregnant women worried about anxiety caused by ECS compared with the non-pregnant group (21.1% vs. 7.4%, P = 0.0006).

Conclusion

Our study demonstrates that expanded carrier screening was perceived as a better screening by most women. Prepregnancy ECS maybe a better approach than ECS during pregnancy, as it allows more reproductive options and may cause less anxiety. Nevertheless, implementation of universal panethnic ECS will need more patient education, ways to reduce anxiety, and consensus on optimal timing in offering ECS.

Expanded carrier screening in Chinese patients seeking the help of assisted reproductive technology

Background

Expanded carrier screening (ECS) has emerged as an effective approach to identify at‐risk couples (ARCs)—before they initiate attempts at reproduction—who possess a high probability of having a child affected by severe recessive diseases. The objective of this study was to evaluate the clinical utility of ECS in Chinese patients seeking the help of assisted reproductive technology (ART).

Methods

An ECS test, which covers 201 genes implicated in 135 recessive (autosomal or X‐linked) diseases, was routinely offered to all ART patients in a single genetics and in vitro fertilization clinic. Additional options for preimplantation or prenatal genetic diagnosis were discussed and offered to all ARCs. All ECS results were aggregated and the clinical decisions of the ARCs were surveyed.

Results

A total of 2,923 ART patients, representing 1,462 couples, were screened. Overall, 46.73% of the individuals were found to be the carriers for at least 1 of the 135 diseases. Of the tested couples, 2.26% (n = 33) were identified as ARCs. As of the completion of this study, 21 (63.6%) ARCs have decided to avert an affected pregnancy with the help of preimplantation genetic testing for monogenetic conditions. The cumulative carrier rate of the 187 autosomal recessive genes in the ECS panel for the 2,836 Han Chinese individuals without a family history was estimated to be 45.91%. The estimated at‐risk couple rate indicates that the screening for only the top 31 genes with gene carrier rates >0.5% would identify more than 94% of the ARCs identified by screening all 187 genes.

Conclusion

Our study demonstrates that ESC yields a significant clinical value for ART patients in China. In addition, by estimating the yields of the ECS panel, we identify genes that are appropriate for screening the Han population.

Smith-Lemli-Opitz's Syndrome as a Possible Cause of Recurrent Pregnancy Loss: A Case Report

Based on the known carrier frequency of Smith-Lemli-Opitz's syndrome (SLOS), the prevalence of this disease should be significantly higher than what is observed in the population. This may be due to a higher rate of pregnancy loss in affected embryos. Here, we present the case of a couple who underwent expanded carrier screening (ECS) after experiencing three first trimester pregnancy losses. Both parents were found to be carriers of SLOS mutations, and DNA analysis of the fetal remains of the third loss revealed the aborted fetus had inherited both the maternal and paternal mutations. This suggests SLOS as a reason for this patient's recurrent pregnancy loss (RPL), and therefore, ECS should be considered as part of the RPL work-up.

Lessons learned from expanded reproductive carrier screening in self-reported Ashkenazi, Sephardi, and Mizrahi Jewish patients

Background

Next‐generation sequencing (NGS)‐based panels have gained traction as a strategy for reproductive carrier screening. Their value for screening Ashkenazi Jewish (AJ) individuals, who have benefited greatly from population‐wide targeted testing, as well as Sephardi/Mizrahi Jewish (SMJ) individuals (an underserved population), has not been fully explored.

Methods

The clinical utilization by 6,805 self‐reported Jewish individuals of an expanded NGS panel, along with several ancillary assays, was assessed retrospectively. Data were extracted for a subset of 96 diseases that, during the panel design phase, were classified as being AJ‐, SMJ‐, or pan‐Jewish/pan‐ethnic‐relevant.

Results

64.6% of individuals were identified as carriers of one or more of these 96 diseases. Over 80% of the reported variants would have been missed by following recommended AJ screening guidelines. 10.7% of variants reported for AJs were in “SMJ‐relevant genes,” and 31.2% reported for SMJs were in “AJ‐relevant genes.” Roughly 2.5% of individuals carried a novel, likely pathogenic variant. One in 16 linked cohort couples was identified as a carrier couple for at least one of these 96 diseases.

Conclusion

For maximal carrier identification, this study supports using expanded NGS panels for individuals of all Jewish backgrounds. This approach can better empower at‐risk couples for reproductive decision making.

Comparison of pan-ethnic and ethnic-based carrier screening panels for individuals of Ashkenazi Jewish descent

The intent of carrier screening is to identify individuals at risk for having a child with a genetic disorder. American College of Medical Genetics and Genomics (ACMG) guidelines currently recommend that individuals of Ashkenazi Jewish (AJ) descent be screened for carrier status for nine disorders. However, a joint statement from five professional organizations acknowledges benefits of expanded carrier screening and this is becoming common practice. To better understand the impact of expanded carrier screening for the AJ population, we performed a retrospective analysis comparing detection rates for AJ individuals screened by two targeted panels: a pan-ethnic panel comprising 87 disorders and an AJ panel comprising an 18-disorder subset of the pan-ethnic panel. We also extrapolated the detection rates for the 18 AJ disorders from the pan-ethnic panel data and for the nine ACMG-recommended disorders using data from both panels. We found that with the pan-ethnic panel 431/1150 (37.5%) individuals were carriers of at least one disorder, compared to 319/1248 (25.6%) individuals with the AJ panel. If the pan-ethnic panel cohort were tested in the AJ panel or for the nine ACMG-recommended disorders, the detection rates would have been 280/1150 (24.3%) and 207/1150 (18.0%) respectively. Therefore, the pan-ethnic expanded carrier screening panel of 87 disorders increased the carrier detection rate in AJ individuals by approximately 50% and 100%, respectively, compared with a panel of 18 disorders considered relevant to the AJ population and the ACMG-recommended disorders. Twenty disorders accounted for the difference in carrier detection rates between the pan-ethnic and AJ panels. Of these, three were among the 10 most commonly identified disorders. Our findings reinforce published data that targeted AJ panels are less effective than a pan-ethnic panel in carrier detection among AJ individuals and provide metrics to address the impact of expanded carrier screening in this population.

A data-driven evaluation of the size and content of expanded carrier screening panels

PURPOSE

The American College of Obstetricians and Gynecologists (ACOG) proposed seven criteria for expanded carrier screening (ECS) panel design. To ensure that screening for a condition is sufficiently sensitive to identify carriers and reduce residual risk of noncarriers, one criterion requires a per-condition carrier rate greater than 1 in 100. However, it is unestablished whether this threshold corresponds with a loss in clinical detection. The impact of the proposed panel design criteria on at-risk couple detection warrants data-driven evaluation.

METHODS

Carrier rates and at-risk couple rates were calculated in 56,281 patients who underwent a 176-condition ECS and were evaluated for panels satisfying various criteria. Condition-specific clinical detection rates were estimated via simulation.

RESULTS

Different interpretations of the 1-in-100 criterion have variable impact: a compliant panel would include between 3 and 38 conditions, identify 11-81% fewer at-risk couples, and detect 36-79% fewer carriers than a 176-condition panel. If the carrier rate threshold must be exceeded in all ethnicities, ECS panels would lack prevalent conditions like cystic fibrosis. Simulations suggest that the clinical detection rate remains >84% for conditions with carrier rates as low as 1 in 1000.

CONCLUSION

The 1-in-100 criterion limits at-risk couple detection and should be reconsidered.

Inter-lab concordance of variant classifications establishes clinical validity of expanded carrier screening

Expanded carrier screening (ECS) panels that use next‐generation sequencing aim to identify pathogenic variants in coding and clinically relevant non‐coding regions of hundreds of genes, each associated with a serious recessive condition. ECS has established analytical validity and clinical utility, meaning that variants are accurately identified and pathogenic variants tend to alter patients' clinical management, respectively. However, the clinical validity of ECS, that is, correct discernment of whether an identified variant is indeed pathogenic, has only been shown for single conditions, not for panels. Here, we evaluate the clinical validity of a >170‐condition ECS panel by assessing concordance between >12 000 variant interpretations classified with guideline‐based criteria to their corresponding per‐variant combined classifications in ClinVar. We observe 99% concordance at the level of unique variants. A more clinically relevant frequency‐weighted analysis reveals that fewer than 1 in 500 patients are expected to receive a report with a variant that has a discordant classification. Importantly, gene‐level concordance is not diminished for rare ECS conditions, suggesting that large panels do not balloon the panel‐wide false‐positive rate. Finally, because ECS is intended to serve all reproductive‐age couples, we show that classification of novel variants is feasible and scales predictably for a large population.

Lessons Learned from Large-Scale, First-Tier Clinical Exome Sequencing in a Highly Consanguineous Population

We report the results of clinical exome sequencing (CES) on >2,200 previously unpublished Saudi families as a first-tier test. The predominance of autosomal-recessive causes allowed us to make several key observations. We highlight 155 genes that we propose to be recessive, disease-related candidates. We report additional mutational events in 64 previously reported candidates (40 recessive), and these events support their candidacy. We report recessive forms of genes that were previously associated only with dominant disorders and that have phenotypes ranging from consistent with to conspicuously distinct from the known dominant phenotypes. We also report homozygous loss-of-function events that can inform the genetics of complex diseases. We were also able to deduce the likely causal variant in most couples who presented after the loss of one or more children, but we lack samples from those children. Although a similar pattern of mostly recessive causes was observed in the prenatal setting, the higher proportion of loss-of-function events in these cases was notable. The allelic series presented by the wealth of recessive variants greatly expanded the phenotypic expression of the respective genes. We also make important observations about dominant disorders; these observations include the pattern of de novo variants, the identification of 74 candidate dominant, disease-related genes, and the potential confirmation of 21 previously reported candidates. Finally, we describe the influence of a predominantly autosomal-recessive landscape on the clinical utility of rapid sequencing (Flash Exome). Our cohort's genotypic and phenotypic data represent a unique resource that can contribute to improved variant interpretation through data sharing.

The aims of expanded universal carrier screening: Autonomy, prevention, and responsible parenthood

Expanded universal carrier screening (EUCS) entails a population-wide screening offer for multiple disease-causing mutations simultaneously. Although there is much debate about the conditions under which EUCS can responsibly be introduced, there seems to be little discussion about its aim: providing carrier couples with options for autonomous reproductive choice. While this links in with current accounts of the aim of foetal anomaly screening, it is different from how the aim of ancestry-based carrier screening has traditionally been understood: reducing the disease burden in the population. The reasons why the aim of EUCS is presented in terms of 'autonomy' rather than 'prevention' have not been spelled out in the literature. This paper seeks to fill this gap by considering the morally relevant similarities and dissimilarities between foetal anomaly screening, ancestry-based carrier screening and EUCS. When carrier screening is performed in the prenatal period, enhancing autonomy appears the most appropriate aim of EUCS, as the alternative of 'prevention through selective abortion' would urge women to terminate wanted pregnancies. However, when screening is conducted in the preconception period, carrier couples can avoid the birth of affected children by other means than selective abortion, for instance preimplantation genetic diagnosis. To the extent that this increased control over passing on a genetic disorder raises questions of parental responsibility, it seems necessary that the account of the aims of EUCS is wider than only in terms of enhancing reproductive autonomy.

Estimating yields of prenatal carrier screening and implications for design of expanded carrier screening panels

PURPOSE

Prenatal genetic carrier screening can identify parents at risk of having a child affected by a recessive condition. However, the conditions/genes most appropriate for screening remain a matter of debate. Estimates of carrier rates across genes are needed to guide construction of carrier screening panels.

METHOD

We leveraged an exome sequencing database (n = 123,136) to estimate carrier rates across six major ancestries for 415 genes associated with severe recessive conditions.

RESULTS

We found that 32.6% (East Asian) to 62.9% (Ashkenazi Jewish) of individuals are variant carriers in at least one of the 415 genes. For couples, screening all 415 genes would identify 0.17-2.52% of couples as being at risk for having a child affected by one of these conditions. Screening just the 40 genes with carrier rate >1.0% would identify more than 76% of these at-risk couples. An ancestry-specific panel designed to capture genes with carrier rates >1.0% would include 5 to 28 genes, while a comparable panethnic panel would include 40 genes.

CONCLUSION

Our work guides the design of carrier screening panels and provides data to assist in counseling prospective parents. Our results highlight a high cumulative carrier rate across genes, underscoring the need for careful selection of genes for screening.

Clinical impact and cost-effectiveness of a 176-condition expanded carrier screen

PURPOSE

Carrier screening identifies couples at high risk for conceiving offspring affected with serious heritable conditions. Minimal guidelines recommend offering testing for cystic fibrosis and spinal muscular atrophy, but expanded carrier screening (ECS) assesses hundreds of conditions simultaneously. Although medical societies consider ECS an acceptable practice, the health economics of ECS remain incompletely characterized.

METHODS

Preconception screening was modeled using a decision tree comparing minimal screening and a 176-condition ECS panel. Carrier rates from >60,000 patients, primarily with private insurance, informed disease incidence estimates, while cost and life-years-lost data were aggregated from the literature and a cost-of-care database. Model robustness was evaluated using one-way and probabilistic sensitivity analyses.

RESULTS

For every 100,000 pregnancies, 290 are predicted to be affected by ECS-panel conditions, which, on average, increase mortality by 26 undiscounted life-years and individually incur $1,100,000 in lifetime costs. Relative to minimal screening, preconception ECS reduces the affected birth rate and is estimated to be cost-effective (i.e.,<$50,000 incremental cost per life-year), findings robust to perturbation.

CONCLUSION

Based on screened patients predominantly with private coverage, preconception ECS is predicted to reduce the burden of Mendelian disease in a cost-effective manner compared with minimal screening. The data and framework herein may facilitate similar assessments in other cohorts.

A case for expanding carrier testing to include actionable X-linked disorders

A research study utilizing whole-genome sequence analysis for preconception carrier screening provided a genome-first detection of a severe de novo Factor VIII mutation in a woman with implications for pregnancy management and life-saving interventions of her newborn son, and a challenge to the existing paradigm regarding carrier testing.

Ethical quandaries around expanded carrier screening in third-party reproduction

Although current screening methods of gamete donors are capable of reducing the incidence of genetic anomalies in donor offspring below general population levels, targeted screening for a large number of conditions (expanded carrier screening or ECS) could be considered as part of the routine selection procedure for gamete donors. There are, however, important drawbacks to its practical implementation. Excluding all carriers of severe recessive monogenic pediatric disorders would disqualify virtually all donors, and other approaches negatively affect cost (and therefore access), present dilemmas in regard to disclosure of genetic findings, and/or overburden the intended parents. In all of the scenarios considered, adequate genetic counseling will be of central importance. Besides looking at benefits and drawbacks of possible ways of implementing ECS, we also examine whether a moral obligation exists to adopt ECS at all and on whose shoulders such an alleged obligation would rest: policymakers, medical staff at fertility clinics, sperm and egg banks, the intended parents? We argue that given the small risk reduction brought about by ECS, the possible negative effects of its implementation, and the absence of widespread preconception carrier screening in the general population, it is inconsistent to argue that there is a moral obligation to perform ECS in the context of donor conception. Finally, implications for the donors are discussed.

Comparing ethnicity-based and expanded carrier screening methods at a single fertility center reveals significant differences in carrier rates and carrier couple rates

PURPOSE

To evaluate the efficiency of expanded carrier screening (ECS) compared with ethnicity-based screening in identifying carriers.

METHODS

A total of 4232 infertility patients underwent ECS from a single genetic testing laboratory at our center between June 2013 and July 2015. Self-reported ethnicity was recorded. Carrier rates based on ECS were calculated. In addition, carrier status was determined for two other screening panels: ethnicity-based guidelines or the ECS panel recommended by the American College of Obstetricians and Gynecologists (ACOG) using ECS results. Carrier rate and carrier couple rates were compared in the overall study population and in each self-reported ethnicity.

RESULTS

The ECS panel used to screen the patient population identified 1243 carriers (29.4%). For the same population, ethnicity-based screening and the ACOG panel would have identified 359 (8.5%) and 659 carriers (15.6%), respectively, representing statistically significant differences. Differences in identifying carriers across self-reported ethnicities varied. In 15 couples (1.2%), both partners carried pathogenic variants for the same genes, 47% of whom would have been missed had screening been ethnicity-based.

CONCLUSION

We propose that all reproductive-aged women should be offered ECS. Carrier couple rates would likely increase further with expansion of the panel, playing a pivotal role in preventing genetic disease in fertility clinics.

Clinical utility of expanded carrier screening: results-guided actionability and outcomes

PURPOSE

Expanded carrier screening (ECS) informs couples of their risk of having offspring affected by certain genetic conditions. Limited data exists assessing the actions and reproductive outcomes of at-risk couples (ARCs). We describe the impact of ECS on planned and actual pregnancy management in the largest sample of ARCs studied to date.

METHODS

Couples who elected ECS and were found to be at high risk of having a pregnancy affected by at least one of 176 genetic conditions were invited to complete a survey about their actions and pregnancy management.

RESULTS

Three hundred ninety-one ARCs completed the survey. Among those screened before becoming pregnant, 77% planned or pursued actions to avoid having affected offspring. Among those screened during pregnancy, 37% elected prenatal diagnostic testing (PNDx) for that pregnancy. In subsequent pregnancies that occurred in both the preconception and prenatal screening groups, PNDx was pursued in 29%. The decision to decline PNDx was most frequently based on the fear of procedure-related miscarriage, as well as the belief that termination would not be pursued in the event of a positive diagnosis.

CONCLUSION

ECS results impacted couples' reproductive decision-making and led to altered pregnancy management that effectively eliminates the risk of having affected offspring.

Introduction: Reproductive genetics: bringing clarity to a foreign language

Genomic based technologies are firmly implanted into clinical medicine. They arrived rapidly and their uses continue to evolve in both the pre and postconception periods. These technologies migrated from the prenatal arena into the domain of the reproductive endocrinology and infertility specialists in some cases nearly simultaneously (expanded carrier screening), in others more slowly (chromosome microarrays), and for some technologies the ethical and cost concerns have resulted in a slower diffusion across the disciplines. This month's Views and Reviews presents five different technologies that have disrupted the delivery of preimplantation and prenatal genetic services areas, including the pros and cons of expanded carrier screening in the preconception period and from the perspective of both sperm and egg donation; prenatal genetic screening using cell free DNA for fetal aneuploidy; chromosomal microarray in the context of prenatal diagnosis after amniocentesis or chorionic villous sampling, and a review of the development of next-generation sequencing technology which allows the anticipated transition from single variant screening to exome sequencing. In this series we focus towards improving the knowledge base to provide some simplicity to a rapidly evolving field.

A systematic analysis of online marketing materials used by providers of expanded carrier screening

PURPOSE

Expanded carrier screening (ECS) for a large number of recessive disorders is available to prospective parents through commercial providers. This study aimed to analyze the content of marketing materials on ECS providers' websites.

METHODS

To identify providers of ECS tests, we undertook a comprehensive online search, reviewed recent academic literature on commercial carrier screening, and consulted with colleagues familiar with the current ECS landscape. The identified websites were archived in April 2017, and inductive content analysis was performed on website text, brochures and educational materials, and video transcripts.

RESULTS

We identified 18 ECS providers, including 16 commercial genetic testing companies. Providers typically described ECS as an important family planning tool. The content differed in both the tone used to promote ECS and the accuracy and completeness of the test information provided. We found that most providers offered complimentary genetic counseling to their consumers, although this was often optional, limited to the posttest context, and, in some cases, appeared to be available only to test-positive individuals.

CONCLUSION

The quality of ECS providers' websites could be improved by offering more complete and accurate information about ECS and their tests. Providers should also ensure that all carrier couples receive posttest genetic counseling to inform their subsequent reproductive decision making.

Recent developments in genetics and medically-assisted reproduction: from research to clinical applications†‡

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively-parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Outcomes of an International Workshop on Preconception Expanded Carrier Screening: Some Considerations for Governments

Background

Consideration of expanded carrier screening has become an emerging issue for governments. However, traditional criteria for decision-making regarding screening programs do not incorporate all the issues relevant to expanded carrier screening. Further, there is a lack of consistent guidance in the literature regarding the development of appropriate criteria for government assessment of expanded carrier screening. Given this, a workshop was held to identify key public policy issues related to preconception expanded carrier screening, which governments should consider when deciding whether to publicly fund such programs.

Methods

In June 2015, a satellite workshop was held at the European Society of Human Genetics Conference. It was structured around two design features: (1) the provision of information from a range of perspectives and (2) small group deliberations on the key issues that governments need to consider and the benefits, risks, and challenges of implementing publicly funded whole-population preconception carrier screening.

Results

Forty-one international experts attended the workshop. The deliberations centered primarily on the conditions to be tested and the elements of the screening program itself. Participants expected only severe conditions to be screened but were concerned about the lack of a consensus definition of “severe.” Issues raised regarding the screening program included the purpose, benefits, harms, target population, program acceptability, components of a program, and economic evaluation. Participants also made arguments for consideration of the accuracy of screening tests.

Conclusion

A wide range of issues require careful consideration by governments that want to assess expanded carrier screening. Traditional criteria for government decision-making regarding screening programs are not a “best fit” for expanded carrier screening and new models of decision-making with appropriate criteria are required. There is a need to define what a “severe” condition is, to build evidence regarding the reliability and accuracy of screening tests, to consider the equitable availability and downstream effects on and costs of follow-up interventions for those identified as carriers, and to explore the ways in which the components of a screening program would be impacted by unique features of expanded carrier screening.

Growing complexity of (expanded) carrier screening: Direct-to-consumer, physician-mediated, and clinic-based offers

Since the introduction of out-of-hospital health-related genetic tests more than a decade ago, the landscape of genetic testing services has grown in complexity. Although initially most genetic tests for health purposes were offered as direct-to-consumer services, that is, without the mediation of a medical professional, currently many commercial providers require that their tests be ordered by a licensed physician. At the same time, some commercially developed health-related genetic tests are gaining support from the professional medical community and are finding their way into clinical practice. Therefore, we differentiated between three types of genetic testing offers: direct-to-consumer, physician-mediated, and clinic-based genetic testing. Expanded carrier screening tests for recessive disorders are currently available through all the three models of genetic testing. Herein, we review the present landscape of expanded carrier screening offers by highlighting the distinct issues associated with each of the three types of genetic testing.

NGS-Based Assay for the Identification of Individuals Carrying Recessive Genetic Mutations in Reproductive Medicine

Next-generation sequencing (NGS) has the capacity of carrier screening in gamete donation (GD) programs. We have developed and validated an NGS carrier-screening test (qCarrier test) that includes 200 genes associated with 368 disorders (277 autosomal recessive and 37 X-linked). Carrier screening is performed on oocyte donation candidates and the male partner of oocyte recipient. Carriers of X-linked conditions are excluded from the GD program, whereas donors are chosen who do not carry mutations for the same gene/disease as the recipients. The validation phase showed a high sensitivity (>99% sensitivity) detecting all single-nucleotide variants, 13 indels, and 25 copy-number variants included in the validation set. A total of 1,301 individuals were analysed with the qCarrier test, including 483 candidate oocyte donors and 635 receptor couples, 105 females receiving sperm donation, and 39 couples seeking pregnancy. We identified 56% of individuals who are carriers for at least one genetic condition and 1.7% of female donors who were excluded from the program due to a carrier state of X-linked conditions. Globally, 3% of a priori assigned donations had a high reproductive risk that could be minimized after testing. Genetic counselling at different stages is essential for helping to facilitate a successful and healthy pregnancy.

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.