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

Laboratory testing for preconception/prenatal carrier screening: A technical standard of the American College of Medical Genetics and Genomics (ACMG)

Carrier screening has historically assessed a relatively small number of autosomal recessive and X-linked conditions selected based on frequency in a specific subpopulation and association with severe morbidity or mortality. Advances in genomic technologies enable simultaneous screening of individuals for several conditions. The American College of Medical Genetics and Genomics recently published a clinical practice resource that presents a framework when offering screening for autosomal recessive and X-linked conditions during pregnancy and preconception and recommends a tier-based approach when considering the number of conditions to screen for and their frequency within the US population in general. This laboratory technical standard aims to complement the practice resource and to put forth considerations for clinical laboratories and clinicians who offer preconception/prenatal carrier screening.

Aspiring toward equitable benefits from genomic advances to individuals of ancestrally diverse backgrounds

Advancements in genomic technologies have shown remarkable promise for improving health trajectories. The Human Genome Project has catalyzed the integration of genomic tools into clinical practice, such as disease risk assessment, prenatal testing and reproductive genomics, cancer diagnostics and prognostication, and therapeutic decision making. Despite the promise of genomic technologies, their full potential remains untapped without including individuals of diverse ancestries and integrating social determinants of health (SDOHs). The NHGRI launched the 2020 Strategic Vision with ten bold predictions by 2030, including "individuals from ancestrally diverse backgrounds will benefit equitably from advances in human genomics." Meeting this goal requires a holistic approach that brings together genomic advancements with careful consideration to healthcare access as well as SDOHs to ensure that translation of genetics research is inclusive, affordable, and accessible and ultimately narrows rather than widens health disparities. With this prediction in mind, this review delves into the two paramount applications of genetic testing-reproductive genomics and precision oncology. When discussing these applications of genomic advancements, we evaluate current accessibility limitations, highlight challenges in achieving representativeness, and propose paths forward to realize the ultimate goal of their equitable applications.

Exploring attitudes and experiences with reproductive genetic carrier screening among couples seeking medically assisted reproduction: a longitudinal survey study

PURPOSE

This study aimed to assess the attitudes and experiences of subfertile couples applying for medically assisted reproduction (MAR) using their own gametes towards reproductive genetic carrier screening (RGCS) for monogenic conditions.

METHODS

A prospective survey study was conducted where subfertile couples were recruited from the fertility centre of a university hospital in Flanders, Belgium. Participants were offered RGCS free of charge and completed self-administered questionnaires at three different time points.

RESULTS

The study sample consisted of 26 couples. Most participants had no children, did not consider themselves as religious, and had some form of higher education. Overall, attitudes towards RGCS were mostly positive and the intention to participate in RGCS was high. Anxiety scores were only elevated and clinically relevant for a limited number of participants. A large proportion of participants would consider preventive reproductive options like prenatal diagnosis or in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) combined with pre-implantation genetic testing for monogenic conditions (PGT-M) in the event of an increased likelihood of conceiving a child with a hereditary condition. Participants were satisfied with their decision to undergo RGCS, and the majority would recommend RGCS to other couples.

CONCLUSION

Our study findings suggest that subfertile couples applying for MAR using their own gametes find RGCS acceptable and have a positive attitude towards it. This study provides valuable insights into the perspectives of these couples, highlighting the need for appropriate counseling and timely information provision.

Multilevel barriers and facilitators to widespread use of preconception carrier screening in the United States

PURPOSE

Although preconception reproductive genetic carrier screening (RGCS) is preferred to screening during pregnancy, population-wide preconception screening is not routinely performed in the United States. We explored the multilevel barriers to the widespread adoption of preconception RGCS in the United States via key informant interviews.

METHODS

Semi-structured virtual video interviews were conducted with 29 informants with a breadth of professional expertise between May and October 2022. Data collection and qualitative analyses were guided by the Consolidated Framework for Implementation Research and socioecological model. Analysis focused on identifying barriers to delivering preconception RGCS at and across different levels of health care and exploring potential facilitators of preconception RGCS delivery.

RESULTS

Barriers to preconception RGCS were identified at the levels of test characteristics, patients and couples, clinicians and care teams, and the external health care and policy environments. Across the different levels of care delivery, 3 themes of barriers emerged: (1) fragmentation and inconsistencies hinder care delivery, (2) gaps in knowledge, misconceptions, and uncertainties about RGCS are pervasive, and (3) expanding preconception RGCS in the diverse US population presents unique implementation challenges. Potential solutions were detailed by informants.

CONCLUSION

Identifying individual and thematic barriers to preconception RGCS delivery may help to define strategies to alleviate obstacles.

Implementing preconception expanded carrier screening in a universal health care system: A model-based cost-effectiveness analysis

PURPOSE

The limited evidence available on the cost-effectiveness (CE) of expanded carrier screening (ECS) prevents its widespread use in most countries, including Italy. Herein, we aimed to estimate the CE of 3 ECS panels (ie, American College of Medical Genetics and Genomics [ACMG] Tier 1 screening, "Focused Screening," testing 15 severe, highly penetrant conditions, and ACMG Tier 3 screening) compared with no screening, the health care model currently adopted in Italy.

METHODS

The reference population consisted of Italian couples seeking pregnancy with no increased personal/familial genetic risk. The CE model was developed from the perspective of the Italian universal health care system and was based on the following assumptions: 100% sensitivity of investigated screening strategies, 77% intervention rate of at-risk couples (ARCs), and no risk to conceive an affected child by risk-averse couples opting for medical interventions.

RESULTS

The incremental CE ratios generated by comparing each genetic screening panel with no screening were: -14,875 ± 1,208 €/life years gained (LYG) for ACMG1S, -106,863 ± 2,379 €/LYG for Focused Screening, and -47,277 ± 1,430 €/LYG for ACMG3S. ACMG1S and Focused Screening were dominated by ACMG3S. The parameter uncertainty did not significantly affect the outcome of the analyses.

CONCLUSION

From a universal health care system perspective, all the 3 ECS panels considered in the study would be more cost-effective than no screening.

Carrier Screening Programs for Cystic Fibrosis, Fragile X Syndrome, Hemoglobinopathies and Thalassemia, and Spinal Muscular Atrophy: A Health Technology Assessment

Background

We conducted a health technology assessment to evaluate the safety, effectiveness, and cost-effectiveness of carrier screening programs for cystic fibrosis (CF), fragile X syndrome (FXS), hemoglobinopathies and thalassemia, and spinal muscular atrophy (SMA) in people who are considering a pregnancy or who are pregnant. We also evaluated the budget impact of publicly funding carrier screening programs, and patient preferences and values.

Methods

We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using the Cochrane Risk of Bias tool and the Risk of Bias Assessment tool for Non-randomized Studies (RoBANS), and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature search and conducted cost-effectiveness analyses comparing preconception or prenatal carrier screening programs to no screening. We considered four carrier screening strategies: 1) universal screening with standard panels; 2) universal screening with a hypothetical expanded panel; 3) risk-based screening with standard panels; and 4) risk-based screening with a hypothetical expanded panel. We also estimated the 5-year budget impact of publicly funding preconception or prenatal carrier screening programs for the given conditions in Ontario. To contextualize the potential value of carrier screening, we spoke with 22 people who had sought out carrier screening.

Results

We included 107 studies in the clinical evidence review. Carrier screening for CF, hemoglobinopathies and thalassemia, FXS, and SMA likely results in the identification of couples with an increased chance of having an affected pregnancy (GRADE: Moderate). Screening likely impacts reproductive decision-making (GRADE: Moderate) and may result in lower anxiety among pregnant people, although the evidence is uncertain (GRADE: Very low).We included 21 studies in the economic evidence review, but none of the study findings were directly applicable to the Ontario context. Our cost-effectiveness analyses showed that in the short term, preconception or prenatal carrier screening programs identified more at-risk pregnancies (i.e., couples that tested positive) and provided more reproductive choice options compared with no screening, but were associated with higher costs. While all screening strategies had similar values for health outcomes, when comparing all strategies together, universal screening with standard panels was the most cost-effective strategy for both preconception and prenatal periods. The incremental cost-effectiveness ratios (ICERs) of universal screening with standard panels compared with no screening in the preconception period were $29,106 per additional at-risk pregnancy detected and $367,731 per affected birth averted; the corresponding ICERs in the prenatal period were about $29,759 per additional at-risk pregnancy detected and $431,807 per affected birth averted.We estimated that publicly funding a universal carrier screening program in the preconception period over the next 5 years would require between $208 million and $491 million. Publicly funding a risk-based screening program in the preconception period over the next 5 years would require between $1.3 million and $2.7 million. Publicly funding a universal carrier screening program in the prenatal period over the next 5 years would require between $128 million and $305 million. Publicly funding a risk-based screening program in the prenatal period over the next 5 years would require between $0.8 million and $1.7 million. Accounting for treatment costs of the screened health conditions resulted in a decrease in the budget impact of universally provided carrier screening programs or cost savings for risk-based programs.Participants value the perceived potential positive impact of carrier screening programs such as medical benefits from early detection and treatment, information for reproductive decision-making, and the social benefit of awareness and preparation. There was a strong preference expressed for thorough, timely, unbiased information to allow for informed reproductive decision-making.

Conclusions

Carrier screening for CF, FXS, hemoglobinopathies and thalassemia, and SMA is effective at identifying at-risk couples, and test results may impact preconception and reproductive decision-making.The cost-effectiveness and budget impact of carrier screening programs are uncertain for Ontario. Over the short term, carrier screening programs are associated with higher costs, and also higher chances of detecting at-risk pregnancies compared with no screening. The 5-year budget impact of publicly funding universal carrier screening programs is larger than that of risk-based programs. However, accounting for treatment costs of the screened health conditions results in a decrease in the total additional costs for universal carrier screening programs or in cost savings for risk-based programs.The people we spoke with who had sought out carrier screening valued the potential medical benefits of early detection and treatment, particularly the support and preparation for having a child with a potential genetic condition.

Demographic Characteristics Associated With Perceptions of Personal Utility in Genetic and Genomic Testing: A Systematic Review

Importance

The expansion of genetic and genomic testing in health care has led to recognition that these tests provide personal as well as clinical utility to patients and families. However, available systematic reviews on this topic have not reported the demographic backgrounds of participants in studies of personal utility, leaving generalizability unclear.

Objective

To determine the demographic characteristics of participants in studies examining the personal utility of genetic and genomic testing in health care.

Evidence Review

For this systematic review, we utilized and updated the results of a highly cited 2017 systematic review on the personal utility of genetics and genomics, which identified relevant articles published between January 1, 2003, and August 4, 2016. We also used the original methods to update this bibliography with literature published subsequently up to January 1, 2022. Studies were screened for eligibility by 2 independent reviewers. Eligible studies reported empirical data on the perspectives of patients, family members, and/or the general public in the US on the personal utility of any type of health-related genetic or genomic test. We utilized a standardized codebook to extract study and participant characteristics. We summarized demographic characteristics descriptively across all studies and by subgroup based on study and participant characteristics.

Findings

We included 52 studies with 13 251 eligible participants. Sex or gender was the most frequently reported demographic characteristic (48 studies [92.3%]), followed by race and ethnicity (40 studies [76.9%]), education (38 studies [73.1%]), and income (26 studies [50.0%]). Across studies, participants disproportionately were women or female (mean [SD], 70.8% [20.5%]), were White (mean [SD], 76.1% [22.0%]), had a college degree or higher (mean [SD], 64.5% [19.9%]), and reported income above the US median (mean [SD], 67.4% [19.2%]). Examination of subgroups of results by study and participant characteristics evidenced only small shifts in demographic characteristics.

Conclusions and Relevance

This systematic review examined the demographic characteristics of individual participants in studies of the personal utility of health-related genetic and genomic testing in the US. The results suggest that participants in these studies were disproportionately White, college-educated women with above-average income. Understanding the perspectives of more diverse individuals regarding the personal utility of genetic and genomic testing may inform barriers to research recruitment and uptake of clinical testing in currently underrepresented populations.

Clinical application value of expanded carrier screening in the population of childbearing age

OBJECTIVE

The objective of this study was to explore the clinical utility of the implementation of expanded carrier screening (ECS) in Chinese population of childbearing age.

MATERIALS AND METHODS

Based on capillary electrophoresis, a first-generation sequencing technology, a prospective screening study of carriers of 15 single-gene diseases was carried out in 327 subjects in Anhui Province, including 84 couples and 159 women of childbearing age, the disease carrier rate, types of screened pathogenic genes, and incidence of both partners carrying the same pathogenic genes were summarized and analyzed.

RESULTS

In 320 people with normal phenotypes who underwent ECS for 15 genetic diseases and 7 spouses who underwent targeted gene sequencing, 65 carriers of at least one disease were detected, with a total carrier rate of 20.31% (65/320). Among the 65 carriers, 81.54% (53/65) carried one genetic variant, 16.92% (11/65) carried two genetic variants, and 1.54% (1/65) carried three genetic variants. In this study, the three diseases with the highest carrier rates were hereditary deafness (8.13%, 26/320), Wilson's disease (4.06%, 13/320), and phenylketonuria (3.13%, 10/320). One high-risk couple (1.19%, 1/84) was detected.

CONCLUSIONS

It has certain clinical application value to implement ECS in the population of childbearing age in China.

Maternal FMR1 alleles expansion in newborns during transmission: a prospective cohort study

INTRODUCTION

The CGG repeats in the 5' untranslated region of the fragile X mental retardation 1 gene (FMR1) gene shows increased instability upon maternal transmission. Maternal FMR1 intermediate (45-54 repeats) and premutation (PM: 55-<200 repeats) alleles usually expand to full mutation (>200 repeats) alleles in offspring and consequently, cause fragile X syndrome (FXS) in them.

METHODS

In a prospective cohort study, Pakistani pregnant women in prenatal care were first screened for FMR1 expanded alleles. In the follow-up, pregnancy outcomes in women carrying FMR1 expanded alleles were recorded and their newborn offspring were also screened for FXS.

RESULTS

In a total of 1950 pregnant women, 89 (4.6%) were detected carriers for FMR1 expanded alleles; however, rates of detection of expanded alleles were found significantly high in women with a history of FXS. In addition, miscarriages and birth of affected newborns with FXS were significantly more common in women carrying large size PM alleles and had a history of FXS (P = 0.0494 and P = 0.0494, respectively).

CONCLUSIONS

The current study provides the first evidence of screening Pakistani pregnant women for FMR1 expanded alleles in prenatal care. Moreover, the miscarriage was also detected as a clinical predictor for FXS.

IMPACT

Offspring would have a higher risk of developing FXS due to maternal FMR1 alleles expansions during transmission. This is the first prospective cohort study in Pakistan for finding FMR1 allelic status of pregnant women and their newborn offspring in follow-up. The robust offspring risk for FXS estimated in this study may be valuable information for genetic counseling of women carriers for FMR1 expanded alleles. The family history and miscarriage were detected as effective indicators for FXS carrier screening in Pakistani women.

Incidental molecular diagnoses and heterozygous risk alleles in a carrier screening cohort

PURPOSE

Expanded pan-ethnic carrier screening is an effective tool for the management of reproductive risk. However, growth in the number of conditions screened, in combination with increasingly more comprehensive test methodologies, can lead to the detection of genetic findings that may affect the health of the tested individual. The objective of this study was to investigate the frequency of pathogenic genotypes in a presumed healthy carrier screening cohort to facilitate broader discussions regarding disclosure of genetic information from carrier screening.

METHODS

A retrospective analysis of 73,755 targeted carrier screens was performed to identify individuals with pathogenic genotypes and heterozygous risk alleles.

RESULTS

In this study, we identified 79 individuals (0.11%) with pathogenic genotypes associated with moderate to profound autosomal recessive or X-linked conditions. In addition, 10 cases had chromosome X dosage abnormalities suggestive of a sex chromosome abnormality. Heterozygote risk alleles represented the majority of ancillary findings in this cohort, including 280 female carriers of FMR1 premutation alleles, 15 heterozygous females with pathogenic DMD variants, and 174 heterozygotes with pathogenic variants in genes that may confer increased risk for somatic malignancies in the heterozygous state.

CONCLUSION

These data suggest that nearly 1% of individuals undergoing carrier screening will have a finding that may require clinical evaluation or surveillance.

Couple screening for recessively inherited disorders

Couple screening aims to identify couples with an increased risk of having a child affected with an autosomal recessive or X-linked disorder, in order to facilitate informed reproductive decision making. Both expectant parents should be screened as a single entity, instead of individual testing. Carrier testing was typically performed for a few relatively common recessive disorders associated with significant morbidity, reduced life expectancy and often because of a considerably higher carrier frequency in a specific population for certain diseases. However, new genetic testing technologies enable the expansion of screening to multiple conditions, genes and sequence variants. There are multiple reproductive options for screening couples at risk, particularly when genetic traits are detected in the preconception period.

Genetic Counselling Needs for Reproductive Genetic Carrier Screening: A Scoping Review

Reproductive genetic carrier screening provides individuals and couples with information regarding their risk of having a child affected by an autosomal recessive or X-linked recessive genetic condition. This information allows them the opportunity to make reproductive decisions in line with their own beliefs and values. Traditionally, carrier screening has been accessed by family members of affected individuals. In recent years, improvements to accessibility and updates to recommendations suggest that all women planning or in early pregnancy should be offered reproductive genetic carrier screening. As uptake moves towards the population scale, how can the genetic counselling needs of such large-scale screening be met? A scoping review of the literature was performed to ascertain what the genetic counselling needs of reproductive genetic carrier screening are, and what future research is needed. Four broad themes were identified in the existing literature: (1) The offer-when and in what context to offer screening; (2) Information-the importance of and what to include in education, and pre- and post-test counselling; (3) Who and how-who the genetic counselling is performed by and how; (4) Personalization-how do we find the balance between standardized and individualized approaches? Based on the existing literature, we present a set of recommendations for consideration in implementing population-scale reproductive genetic carrier screening as well as suggested areas for future research.

Carrier screening: An update

Genetic carrier screening (CS) for reproductive decision making was introduced 50 years ago. Technological advances and improvements in knowledge of the human genome makes multi-disease, pan-ethnic CS possible. Such screening will identify most individuals as carriers of at least one autosomal recessive or X-linked recessive disorder. Past experiences and best practices have provided a framework for CS. Although its clinical utilization is increasing, some challenges remain. In this study, several aspects of CS panel implementation have been addressed including how to evaluate the quantitative gene inclusion criteria, how to classify the severity of genetic conditions, how to understand clinical validity at the level of gene-disease association and variant classification, and how to minimize residual risks.

Outcomes of Importance to Patients in Reproductive Genetic Carrier Screening: A Qualitative Study to Inform a Core Outcome Set

There is significant heterogeneity in the outcomes assessed across studies of reproductive genetic carrier screening (RGCS). Only a small number of studies have measured patient-reported outcomes or included patients in the selection of outcomes that are meaningful to them. This study was a cross-sectional, qualitative study of 15 patient participants conducted to inform a core outcome set. A core outcome set is an approach to facilitate standardisation in outcome reporting, allowing direct comparison of outcomes across studies to enhance understanding of impacts and potential harms. The aim of this study was to incorporate the patient perspective in the development of a core outcome set by eliciting a detailed understanding of outcomes of importance to patients. Data were collected via online, semi-structured interviews using a novel method informed by co-design and the nominal group technique. Data were analysed using reflexive thematic analysis. Outcomes elicited from patient stakeholder interviews highlighted several under-explored areas for future research. This includes the role of grief and loss in increased risk couples, the role of empowerment in conceptualising the utility of RGCS, the impact of societal context and barriers that contribute to negative experiences, and the role of genetic counselling in ensuring that information needs are met and informed choice facilitated as RGCS becomes increasingly routine. Future research should focus on incorporating outcomes that accurately reflect patient needs and experience.

Assessing clinical utility of preconception expanded carrier screening regarding residual risk for neurodevelopmental disorders

The magnitude of clinical utility of preconception expanded carrier screening (ECS) concerning its potential to reduce the risk of affected offspring is unknown. Since neurodevelopmental disorders (NDDs) in their offspring is a major concern of parents-to-be, we addressed the question of residual risk by assessing the risk-reduction potential for NDDs in a retrospective study investigating ECS with different criteria for gene selection and definition of pathogenicity. We used exome sequencing data from 700 parents of children with NDDs and blindly screened for carrier-alleles in up to 3046 recessive/X-linked genes. Depending on variant pathogenicity thresholds and gene content, NDD-risk-reduction potential was up to 43.5% in consanguineous, and 5.1% in nonconsanguineous couples. The risk-reduction-potential was compromised by underestimation of pathogenicity of missense variants (false-negative-rate 4.6%), inherited copy-number variants and compound heterozygosity of one inherited and one de novo variant (0.9% each). Adherence to the ACMG recommendations of restricting ECS to high-frequency genes in nonconsanguineous couples would more than halve the detectable inherited NDD-risk. Thus, for optimized clinical utility of ECS, screening in recessive/X-linked genes regardless of their frequency (ACMG Tier-4) and sensible pathogenicity thresholds should be considered for all couples seeking ECS.

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.

Where is genetic medicine headed? Exploring the perspectives of Canadian genetic professionals on future trends using the Delphi method

Driven by technological and scientific advances, the landscape of genetic medicine is rapidly changing, which complicates strategic planning and decision-making in this area. To address this uncertainty, we sought to understand genetic professionals' opinions about the future of clinical genetic and genomic services in Canada. We used the Delphi method to survey Canadian genetic professionals about their perspectives on whether scenarios about changes in service delivery and the use of genomic testing would be broadly implemented in their jurisdiction by 2030. We conducted two survey rounds; the response rates were 32% (27/84) and 67% (18/27), respectively. The most likely scenario was the universal use of noninvasive prenatal screening. The least likely scenarios involved population-based genome-wide sequencing for unaffected individuals. Overall, the scenarios perceived as most likely were those that have existing evidence about their benefit and potential medical necessity, whereas scenarios were seen as unlikely if they involved emerging technologies. Participants expected that the need for genetic healthcare services would increase by 2030 owing to changes in clinical guidelines and increased use of genome-wide sequencing. This study highlights the uncertainty in the future of genetic and genomic service provision and contributes evidence that could be used to inform strategic planning in clinical genetics.

Establishing the Medical Actionability of Genomic Variants

Actionability is an important concept in medicine that does not have a well-accepted standard definition, nor is there a general consensus on how to establish it. Medical actionability is often conflated with clinical utility, a related but distinct concept. This lack of clarity contributes to practice variation and inconsistent coverage decisions in genomic medicine, leading to the potential for systematic bias in the use of evidence-based interventions. We clarify how medical actionability and clinical utility are distinct and then discuss the spectrum of actionability, including benefits for the person, the family, and society. We also describe applications across the life course, including prediction, diagnosis, and treatment. Current challenges in assessing the medical actionability of identified genomic variants include gaps in the evidence, limited contexts with practice guidelines, and subjective aspects of medical actionability. A standardized and authoritative assessment of medical actionability is critical to implementing genomic medicine in a fashion that improves population health outcomes and reduces health disparities. Expected final online publication date for the Annual Review of Genomics and Human Genetics, Volume 23 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Comprehensive analysis of recessive carrier status using exome and genome sequencing data in 1543 Southern Chinese

Traditional carrier screening has been utilized for the detection of carriers of genetic disorders. Since a comprehensive assessment of the carrier frequencies of recessive conditions in the Southern Chinese population is not yet available, we performed a secondary analysis on the spectrum and carrier status for 315 genes causing autosomal recessive disorders in 1543 Southern Chinese individuals with next-generation sequencing data, 1116 with exome sequencing and 427 with genome sequencing data. Our data revealed that 1 in 2 people (47.8% of the population) was a carrier for one or more recessive conditions, and 1 in 12 individuals (8.30% of the population) was a carrier for treatable inherited conditions. In alignment with current American College of Obstetricians and Gynecologists (ACOG) pan-ethnic carrier recommendations, 1 in 26 individuals were identified as carriers of cystic fibrosis, thalassemia, and spinal muscular atrophy in the Southern Chinese population. When the >1% expanded carrier screening rate recommendation by ACOG was used, 11 diseases were found to meet the criteria in the Southern Chinese population. Approximately 1 in 3 individuals (35.5% of the population) were carriers of these 11 conditions. If the 1 in 200 carrier frequency threshold is used, and additional seven genes would meet the criteria, and 2 in 5 individuals (38.7% of the population) would be detected as a carrier. This study provides a comprehensive catalogue of the carrier spectrum and frequency in the Southern Chinese population and can serve as a reference for careful evaluation of the conditions to be included in expanded carrier screening for Southern Chinese people.

Fragile X premutation carrier screening in Pakistani preconception women in primary care consultation

Purpose

Women of reproductive age who carry fragile X premutation (PM) alleles have 56 to 200 CGG repeats in the 5′-untranslated region of FMR1 gene are at increased risk for producing children with intellectual disabilities (ID) or autism spectrum disorders (ASD) due to expansion of PM alleles to full mutation alleles (> 200 repeats) during maternal transmission.

Methods

In present study fragile X PM carrier screening was performed in total 808 women who were consulting primary health care centers for preconception care in Khyber Pakhtunkhwa region of Pakistan between April, 2018 and December, 2020. Polymerase chain reaction (PCR) was performed for detection of PM carrier women and the CGG repeats number was confirmed by Southern blotting and capillary electrophoresis.

Results

The prevalence rate for PM carriers among preconception women was found to be 0.7% that was contributed by 0.5% women in risk group (RG1) with family history of ID and 0.2% in risk group 2 (RG2) with family history of ASD. PM carrier women had at least one affected child or sibling. In addition, the preconception women with FMR1 PM alleles were found to be at increased risk for primary ovary insufficiency (RG1: P = 0.0265, RG2: P = 0.0389), postpartum depression (RG1: P = 0.0240, RG2: P = 0.0501) and neuropsychiatric disorders (RG1: P = 0.0389, RG2: P = 0.0432).

Conclusions

Current study provides first evidence of fragile X PM carrier screening in Pakistani preconception women in primary care consultation. Findings of current study may help to improve preconception care and to reduce burden of fragile X associated disorders in our population.

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.

Addressing Reproductive Healthcare Disparities through Equitable Carrier Screening: Medical Racism and Genetic Discrimination in United States’ History Highlights the Needs for Change in Obstetrical Genetics Care

Carrier screening, a nearly half-century old practice, aims to provide individuals and couples with information about their risk of having children with serious genetic conditions. Traditionally, the conditions for which individuals were offered screening depended on their self-reported race or ethnicity and which conditions were seen commonly in that population. This process has led to disparities and inequities in care as the multi-racial population in the U.S. has grown exponentially, yet databases used to determine clinical practice guidelines are made up of primarily White cohorts. Technological advancements now allow for pan-ethnic expanded carrier screening (ECS), which screens for many conditions regardless of self-reported race or ethnicity. ECS presents a unique opportunity to promote equitable genetic testing practices in reproductive medicine. However, this goal can only be achieved if we acknowledge and appreciate the innumerable inequities evidenced in reproductive medicine and other socio-legal practices in the United States, and if we intentionally work in concert with healthcare providers, policy makers, advocates, and community health champions to reduce current and future reproductive health disparities. Herein, we provide a brief review of the way that US medical racism and genetic discrimination has shaped the current landscape of carrier screening.

An Introduction: Prenatal Screening, Diagnosis, and Treatment of Single Gene Disorders

Increasing ability to diagnose fetal single gene disorders has changed the prenatal diagnostic paradigm. As fetal sequencing advances, the genomic information obtained can lead to improved prognostic counseling, and elucidation of recurrence risk and future prenatal diagnosis options. For some of these disorders, postnatal molecular therapy, including gene therapy, is available or being studied in clinical trials. Most of the initial research and clinical trials have involved children and adults, but there are potential benefits to treating conditions before birth. Many clinical studies are underway exploring the potential for in utero gene therapy.

Systematic review of outcomes in studies of reproductive genetic carrier screening: Towards development of a core outcome set

PURPOSE

Current practice recommendations support the widespread implementation of reproductive genetic carrier screening (RGCS). These consensus-based recommendations highlight a research gap, with findings from current studies being insufficient to meet the standard required for more rigorous evidence-based recommendations. This systematic review assessed methodological aspects of studies on RGCS to inform the need for a core outcome set.

METHODS

We conducted a systematic search to identify peer-reviewed published studies offering population-based RGCS. Study designs, outcomes, and measurement methods were extracted. A narrative synthesis was conducting using an existing outcome taxonomy and criteria used in the evaluation of genetic screening programs as frameworks.

RESULTS

Sixty-five publications were included. We extracted 120 outcomes representing 24 outcome domains. Heterogeneity in outcome selection, measurement methods and time points of assessment was extensive. Quality appraisal raised concerns for bias. We found that reported outcomes had limited applicability to criteria used to evaluate genetic screening programs.

CONCLUSION

Despite a large body of literature, diverse approaches to research have limited the conclusions that can be cumulatively drawn from this body of evidence. Consensus regarding meaningful outcomes for evaluation of RGCS would be a valuable first step in working towards evidence-based practice recommendations, supporting the development of a core outcome set.

Legal challenges in reproductive genetics

Recent advancements in reproductive genetics have resulted in the availability of an extraordinary amount of new and detailed information for patients and providers. Whereas this information can inform many who are facing difficult clinical decisions, it can also introduce complex and uncertain choices. Expanded carrier screening and preimplantation genetic diagnosis for aneuploidy are important examples of new genetic techniques that are now widely used in reproductive medicine. This paper will explore these techniques through a medical-legal prism to better understand the opportunities and obligations incumbent on both patients and providers in this new age of genetic diagnosis.

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.

What women want: General population perspectives and access to preconception expanded carrier screening

OBJECTIVE

Expanded carrier screening (ECS) assesses the risk of individuals and couples of having a child affected with a set of genetic conditions. Carriers have options available to optimize pregnancy outcomes based on personal values and preferences. The greatest range of options is available prior to pregnancy, therefore professional societies recommend this screening be performed preconception. This study aimed to assess awareness of, and interest in, ECS in women preconception. Additionally, it aimed to evaluate preferences for timing and location of education and availability of ECS.

METHODS

A total of 260 nulliparous women from the general population were surveyed through Qualtrics, a national market research survey platform. Data were delineated using descriptive statistics.

RESULTS

Of this cohort, 43.5% reported being aware of ECS prior to the survey and 77.8% indicated interest. Those previously aware were first informed by family, friends, or independent online research. Interest was primarily driven by a desire for reassurance and to make informed decisions about future pregnancies. Interested respondents indicated a willingness to request testing from providers. Participants showed a preference for education and access from a healthcare provider in person.

CONCLUSION

These findings provide insight regarding when and where to best educate and reach women prior to pregnancy about ECS to maximize pregnancy outcomes.

Technical factors to consider when developing an Expanded Carrier Screening platform

PURPOSE OF REVIEW

Expanded Carrier Screening (ECS) is a genetic test able to detect carriers for a large number of autosomal recessive and X-linked diseases. Its clinical utilization is increasing but some technical aspects for its implementation are still controversial.

RECENT FINDINGS

In the current literature, several aspects of ECS panel implementation have been addressed. One of the most relevant topics involves which genes/pathologies should be included in an optimized ECS panel and which variants should be reported.

SUMMARY

Here, we review the best practice criteria to refine and improve clinical utility and validity of an ECS panel. The criteria for optimal ECS panel implementation include the severity of pathologies, the prevalence of diseases in general population and a definitive or strong gene/disease association. Moreover, we discuss the main complications associated with the reporting of Variant of Uncertain Significance and the need for periodic reassessment.

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.

Utility of Genetic Testing from the Perspective of Parents/Caregivers: A Scoping Review

In genomics, perceived and personal utility have been proposed as constructs of value that include the subjective meanings and uses of genetic testing. Precisely what constitutes these constructs of utility and how they vary by stakeholder perspective remains unresolved. To advance methods for measuring the value of genetic testing in child health, we conducted a scoping review of the literature to characterize utility from the perspective of parents/caregivers. Peer reviewed literature that included empiric findings from parents/caregivers who received genetic test results for an index child and was written in English from 2016-2020 was included. Identified concepts of utility were coded according to Kohler's construct of personal utility. Of 2142 abstracts screened, 33 met inclusion criteria. Studies reflected a range of genetic test types; the majority of testing was pursued for children with developmental or neurodevelopmental concerns. Coding resulted in 15 elements of utility that mapped to Kohler's four domains of personal utility (affective, cognitive, behavioural and social) and one additional medical management domain. An adapted construct of utility for parents/caregivers may enable specific and standardized strategies for researchers to use to generate evidence of the post-test value of genetic testing. In turn, this will contribute to emerging methods for health technology assessment and policy decision making for genomics in child health.

Genetics of recurrent pregnancy loss: a review

PURPOSE OF REVIEW

Human reproduction is remarkably inefficient; with pregnancy loss occurring in 10-30% of clinically recognized pregnancies. Of those, 3-5% of couples experience recurrent pregnancy loss (RPL), more than 50% of who never receive an underlying diagnosis. Herein, we review evidence that genetic changes, including pathogenic variant(s) in highly penetrant genes, may provide an explanation for a proportion of couples with pregnancy loss.

RECENT FINDINGS

Genetic abnormalities that may predispose to pregnancy loss include chromosomal aneuploidy, copy number variants, single-gene changes and others. Although previously limited by the need for hypothesis-driven assessment, advancement of various molecular technologies have sheparded in the opportunity to identify molecular cause of highly heterogeneous conditions, including RPL. The identification of causative genetic aberrations associated with RPL demonstrates a promising area of further research.

SUMMARY

The journey of human development from a single-cell zygote to a term infant is complex process. Early research into copy number variants and highly penetrant single-gene changes may provide diagnosis for a proportion of couples with RPL as well as inform genes critical for early human development.

Expanded carrier screening for recessively inherited disorders: economic burden and factors in decision-making when one individual in a couple is identified as a carrier

PURPOSE

When undergoing expanded carrier screening (ECS), couples are often screened sequentially to reduce need for a second individual's test. It is unknown how often partners of individuals found to be carriers complete the recommended testing with a sequential approach and what factors contribute to decision-making regarding partner testing. Additionally, the economic burden placed on individuals by ECS testing and its effect on partner testing has not been evaluated.

METHODS

In part 1, all individuals at a university-affiliated reproductive endocrinology and infertility practice identified to be carriers of a recessively inherited mutation using the Counsyl/Foresight ECS were included. Conditions were categorized by severity according to a previously described classification system. In part 2, all individuals who underwent ECS with a single test provider between September 1, 2013 and February 1, 2020 were contacted via email to complete a confidential and anonymized online survey.

RESULTS

In part 1, a total of 2061 patients were screened. 36.9% were carriers of one or more recessively inherited disorders. Twenty-seven percent of positively screened individuals did not have their partner screened. Carriers of a moderate condition had a trend towards a reduced odds for having their partner screened compared to a profound condition (OR 0.36, 95% CI 0.12-1.05, p = 0.06). Number of conditions was not predictive of subsequent partner screening (OR 0.95, 95% CI 0.72-1.25, p = 0.72). In part 2, the cost of ECS was not covered by insurance for 54.5% (103/189) and most paid over $300 out-of-pocket for testing (47.6%). The most common reason for not completing partner testing was that the results would not alter their course when seeking conception (33.3%). 73.5% of patients knew that the largest benefit of ECS comes from knowing a partner's results as well as their own.

CONCLUSIONS

Not all carriers of recessively inherited disorders choose to undergo partner screening. Patients found to be carrier of more debilitating genetic disorders may be more likely to screen their reproductive partners. For many, ECS testing is not covered by insurance, and this test may impose a significant economic burden. For some patients, the results of ECS would not change what they would do when seeking conception. Providers should evaluate whether a patient's ECS result would change their treatment course prior to testing.

Current attitudes and preconceptions towards expanded carrier screening in the Eastern Chinese reproductive-aged population

PURPOSE

A growing number of Chinese individuals of reproductive age will face the choice of accepting or refusing expanded carrier screening (ECS). This study aimed to explore the awareness, wishes, and possible misconceptions of ECS among this population, as well as factors affecting their decision-making.

METHODS

Chinese reproductive-aged individuals in Eastern China who sought cell-free fetal DNA screening and peripheral blood karyotype were invited to complete a 31-item ECS survey by scanning a specific quick response code. We evaluated the relationship between awareness, attitudes, and intentions to participate in ECS, along with possible misconceptions.

RESULTS

Overall, 93.1% of participants intended to undergo ECS at their expenses, and 53.6% indicated they would pay less than 1000 CNY (approximately 145 USD) for the test. Around 96.5% of participants had misconceptions about ECS and genetic diseases. Participants whose first reaction was interest, who had prior awareness of the test, or who perceived benefits were more likely to intend to use ECS (p < 0.001). Participants with a bachelor's degree or above or with a household income over 150,000 CNY (approximately 21,700 USD) would be more likely to pay ≥ 1000 CNY (p < 0.05).

CONCLUSIONS

Our study indicates that overall, the Eastern Chinese reproductive-aged population has positive attitudes towards ECS, although there are some misconceptions about ECS and genetic disorders. Population-based ECS appears to be desired by the reproductive-aged people in Eastern China. Steps should be taken to offer ECS along with pre- and post-test education and genetic counseling to raise awareness and to reduce misconceptions.

Female and male perspectives on male partner roles in expanded carrier screening

PURPOSE

To explore facilitators and barriers for male partner follow through carrier screening (CS) after their female partners were identified as carriers, from both male and female perspectives.

METHODS

Participants were either females identified as a carrier through CS (512 participants) or males who had CS (125 participants). Participants were recruited via e-mails with survey links. The survey explored factors surrounding decisions to pursue CS or not.

RESULTS

Males who attended the females' CS appointment were more likely to have CS (OR: 2.07). More male partners of females identified as carriers of severe or profound conditions pursued CS (82.0%) than male partners of females who were carriers for moderate conditions (50.0%). Logistic factors were more impactful for males who pursued CS. Females whose male partners did not test endorsed personal belief factors as most impactful, reporting the perceived low risk (75.0%) and his low concern for the specific condition (65.5%) were the top reasons their partners did not test.

CONCLUSION

Many factors impact how male partners appraise reproductive risk from CS and make decisions regarding their own screening. Advising that male partners attend CS appointments may increase the likelihood of follow through CS. Thorough and repeated risk counseling is indicated.

A Transparent Approach to Calculate Detection Rate and Residual Risk for Carrier Screening

Carrier screening involves detection of carrier status for genes associated with recessive conditions. A negative carrier screening test result bears a nonzero residual risk (RR) for the individual to have an affected child. The RR depends on the prevalence of specific conditions and the detection rate (DR) of the test itself. Herein, we provide a detailed approach for calculating DR and RR. DR was calculated on the basis of the sum of disease allele frequencies (DAFs) of pathogenic variants found in published literature. As a proof of concept, DAF data for cystic fibrosis were compared with society guidelines. The DAF data calculated by this method were consistent with the published cystic fibrosis guideline. In addition, we compared DAF for four genes (ABCC8, ASPA, GAA, and MMUT) across three laboratories, and outlined the likely reasons for discrepancies between these laboratories. The utility of carrier screening is to support couples with information while making reproductive choices. Accurate development of DR and RR is therefore critical. The method described herein provides an unbiased and transparent process to collect, calculate, and report these data.

Perceived barriers to paternal expanded carrier screening following a positive maternal result: To screen or not to screen

Expanded carrier screening identifies individuals who are at risk of having a child with an autosomal recessive condition. The most accurate risk assessment requires that both mother and father undergo carrier screening to determine whether they are carriers of the same autosomal recessive condition. A couple identified as carriers of the same condition has a 25% chance of having a child with that condition. However, the father does not always opt for carrier screening following a positive result in the mother. This study aimed to identify barriers that prevent the father from carrier screening after a positive finding in the mother. A total of 58 women participated in this study. All participants had undergone expanded carrier screening prior to the study and had met with a genetic counselor for a pre-test, informed consent session. Of the 58 women, 34 had partners who did not undergo screening and 24 had partners who did. Participants completed a survey to determine the barriers that prevented the father of the baby's participation. We report that the mother's insurance type, whether the father has insurance, relationship status, and knowledge of the carrier screen showed statistically significant differences between women whose partners underwent screening and those that did not. In summary, our finding suggests that increasing insurance coverage of paternal screening and improving the patient's knowledge of the expanded screen would encourage paternal screening.

Which types of conditions should be included in reproductive genetic carrier screening? Views of parents of children with a genetic condition

Reproductive genetic carrier screening identifies couples with an increased chance of having children with autosomal and X-linked recessive conditions. Initially only offered for single conditions to people with a high priori risk, carrier screening is becoming increasingly offered to individuals/couples in the general population for a wider range of genetic conditions. Despite advances in genomic testing technology and greater availability of carrier screening panels, there is no consensus around which types of conditions to include in carrier screening panels. This study sought to identify which types of conditions parents of children with a genetic condition believe should be included in carrier screening. Participants (n = 150) were recruited through Royal Children's Hospital (RCH) Melbourne outpatient clinics, the Genetic Support Network of Victoria (GSNV) and a databank of children with hearing loss (VicCHILD). This study found that the majority of participants support offering carrier screening for: neuromuscular conditions (n = 128/134, 95.5%), early fatal neurodegenerative conditions (n = 130/141, 92.2%), chronic multi-system disorders (n = 124/135, 91.9%), conditions which cause intellectual disability (n = 128/139, 92.1%) and treatable metabolic conditions (n = 120/138, 87.0%). Views towards the inclusion of non-syndromic hearing loss (n = 88/135, 65.2%) and preventable adult-onset conditions (n = 75/135, 55.6%) were more mixed. Most participants indicated that they would use reproductive options to avoid having a child with the more clinically severe conditions, but most would not do so for clinically milder conditions. A recurring association was observed between participants' views towards carrier screening and their lived experience of having a child with a genetic condition.

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.

Evaluation and classification of severity for 176 genes on an expanded carrier screening panel

Background

Disease severity is important when considering genes for inclusion on reproductive expanded carrier screening (ECS) panels. We applied a validated and previously published algorithm that classifies diseases into four severity categories (mild, moderate, severe, and profound) to 176 genes screened by ECS. Disease traits defining severity categories in the algorithm were then mapped to four severity‐related ECS panel design criteria cited by the American College of Obstetricians and Gynecologists (ACOG).

Methods

Eight genetic counselors (GCs) and four medical geneticists (MDs) applied the severity algorithm to subsets of 176 genes. MDs and GCs then determined by group consensus how each of these disease traits mapped to ACOG severity criteria, enabling determination of the number of ACOG severity criteria met by each gene.

Results

Upon consensus GC and MD application of the severity algorithm, 68 (39%) genes were classified as profound, 71 (40%) as severe, 36 (20%) as moderate, and one (1%) as mild. After mapping of disease traits to ACOG severity criteria, 170 out of 176 genes (96.6%) were found to meet at least one of the four criteria, 129 genes (73.3%) met at least two, 73 genes (41.5%) met at least three, and 17 genes (9.7%) met all four.

Conclusion

This study classified the severity of a large set of Mendelian genes by collaborative clinical expert application of a trait‐based algorithm. Further, it operationalized difficult to interpret ACOG severity criteria via mapping of disease traits, thereby promoting consistency of ACOG criteria interpretation.

Expanded carrier screening for preconception reproductive risk assessment: Prevalence of carrier status in a Mexican population

OBJECTIVE

Genetic carrier screening has the potential to identify couples at risk of having a child affected with an autosomal recessive or X-linked disorder. However, the current prevalence of carrier status for these conditions in developing countries is not well defined. This study assesses the prevalence of carrier status of selected genetic conditions utilizing an expanded, pan-ethnic genetic carrier screening panel (ECS) in a large population of Mexican patients.

METHODS

Retrospective chart review of all patients tested with a single ECS panel at an international infertility center from 2012 to 2018 were included, and the prevalence of positive carrier status in a Mexican population was evaluated.

RESULTS

Eight hundred five individuals were analyzed with ECS testing for 283 genetic conditions. Three hundred fifty-two carriers (43.7%) were identified with 503 pathogenic variants in 145 different genes. Seventeen of the 391 participating couples (4.34%) were identified as being at-risk couples. The most prevalent alleles found were associated with alpha thalassemia, cystic fibrosis, GJB2 nonsyndromic hearing loss, biotinidase deficiency, and familial Mediterranean fever.

CONCLUSION

Based on the prevalence and severity of Mendelian disorders, we recommend that couples who wish to conceive regardless of their ethnicity background explore carrier screening and genetic counseling prior to reproductive medical treatment.

How does carrier status for recessive disorders influence reproductive decisions? A systematic review of the literature

Introduction: Carrier screening for recessive disorders is undertaken by prospective parents to inform their reproductive decisions. With the growing availability of affordable and comprehensive expanded carrier screening (ECS), it is expected that carrier screening will become a standard practice in the future. However, the impact of positive carrier screening results on the reproductive decisions of at-risk couples (ARCs) remains underexplored.Areas covered: We performed a systematic literature review to identify peer-reviewed publications describing the reproductive decisions of ARCs. Our search identified 19 relevant publications spanning the period 1994-2018. By synthesizing available evidence, we found that most ARCs chose to prevent the birth of an affected child and the decision to utilize preventive reproductive options was strongly influenced by the clinical nature of a disorder. However, there was also some heterogeneity in reproductive decisions within the same recessive disorders, suggesting that choices of ARCs can be influenced by factors other than the clinical nature of a disorder.Expert opinion: ECS is becoming increasingly common, which will result in the routine identification of many ARCs. Reproductive decision-making by ARCs is a complex and emotionally challenging process, highlighting the critical role of genetic counseling in the care for these potentially vulnerable patients.

Fragile X syndrome carrier screening accompanied by genetic consultation has clinical utility in populations beyond those recommended by guidelines

Background

Fragile X syndrome (FXS) is the most common inherited form of intellectual disability. Many providers offer preconception or prenatal FXS carrier screening. However, guidelines recommend screening only for those with a family history or undergoing fertility evaluation. Wider screening has been resisted because of concerns about patient understanding of FXS‐associated inheritance patterns and phenotypes. Additionally, the clinical utility has been questioned.

Methods

We addressed these concerns by analyzing reproductive decision‐making and pregnancy management informed by post‐test genetic consultation among 122 FMR1 premutation carriers identified by expanded carrier screening.

Results

Sixty‐three percent of those screened met guidelines screening criteria; the remaining 37% did not. Ninety‐eight percent had undergone post‐test genetic consultation. Of respondents screened preconceptionally, 74% reported planning or pursuing actions to reduce the risk of an affected pregnancy; the extent to which couples planned/pursued these actions was not significantly different between those meeting either screening criterion (76%) versus those meeting neither criterion (55%). Of respondents screened prenatally, 41% pursued prenatal diagnostic testing; the extent to which couples pursued prenatal diagnosis was not significantly different between those who met either screening criterion (37%) versus those who met neither criterion (31%).

Conclusion

These results support the expansion of FXS screening criteria in guidelines.

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.

Sequencing as a first-line methodology for cystic fibrosis carrier screening

Purpose

Medical society guidelines recommend offering genotyping-based cystic fibrosis (CF) carrier screening to pregnant women or women considering pregnancy. We assessed the performance of sequencing-based CF screening relative to genotyping, in terms of analytical validity, clinical validity, clinical impact, and clinical utility.

Methods

Analytical validity was assessed using orthogonal confirmation and reference samples. Clinical validity was evaluated using the CFTR2 database. Clinical impact was assessed using ~100,000 screened patients. Three screening strategies were compared: genotyping 23 guideline-recommended variants (“CF23”), sequencing all coding bases in CFTR (“NGS”), and sequencing with large copy-number variant (CNV) identification (“NGS + CNV”). Clinical utility was determined via self-reported actions of at-risk couples (ARCs).

Results

Analytical accuracy of NGS + CNV was 100% for SNVs, indels, and CNVs; interpretive clinical specificity relative to CFTR2 was 99.5%. NGS + CNV detected 58 ARCs, 18 of whom would have gone undetected with CF23 alone. Most ARCs (89% screened preconceptionally, 56% prenatally) altered pregnancy management, and no significant differences were observed between ARCs with or without at least one non-CF23 variant.

Conclusion

Modern NGS and variant interpretation enable accurate sequencing-based CF screening. Limiting screening to 23 variants does not improve analytical validity, clinical validity, or clinical utility, but does fail to detect approximately 30% (18/58) of ARCs.

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.