Challenging the dogma of the healthy heterozygote: Implications for newborn screening policies and practices

Update on advances in cystic fibrosis towards a cure and implications for primary care clinicians

During the past quarter century, the diagnosis and treatment of cystic fibrosis (CF) have been transformed by molecular sciences that initiated a new era with discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The knowledge gained from that breakthrough has had dramatic clinical impact. Although once a diagnostic dilemma with long delays, preventable deaths, and irreversible pathology, CF can now be routinely diagnosed shortly after birth through newborn screening programs. This strategy of pre-symptomatic identification has eliminated the common diagnostic "odyssey" that was a failure of the healthcare delivery system causing psychologically traumatic experiences for parents. Therapeutic advances of many kinds have culminated in CFTR modulator treatment that can reduce the effects of or even correct the molecular defect in the chloride channel -the basic cause of CF. This astonishing advance has transformed CF care as described fully herein. Despite this impressive progress, there are challenges and controversies in the delivery of care. Issues include how best to achieve high sensitivity newborn screening with acceptable specificity; what course of action is appropriate for children who are identified through the unavoidable incidental findings of screening tests (CFSPID/CRMS cases and heterozygote carriers); how best to ensure genetic counseling; when to initiate the very expensive but life-saving CFTR modulator drugs; how to identify new CFTR modulator drugs for patients with non-responsive CFTR variants; how to adjust other therapeutic modalities; and how to best partner with primary care clinicians. Progress always brings new challenges, and this has been evident worldwide for CF. Consequently, this article summarizes the major advances of recent years along with controversies and describes their implications with an international perspective.

ECFS standards of care on CFTR-related disorders: Towards a comprehensive program for affected individuals

After three publications defining an updated guidance on the diagnostic criteria for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (pwCFTR-RDs), establishing its relationship to CFTR-dysfunction and describing the individual disorders, this fourth and last paper in the series addresses some critical challenges facing health care providers and pwCFTR-RD. Topics included are: 1) benefits and obstacles to collect data from pwCFTR-RD are discussed, together with the opportunity to integrate them into established CF-registries; 2) the potential of infants designated CRMS/CFSPID to develop a CFTR-RD and how to communicate this information; 3) a description of the challenges in genetic counseling, with particular regard to phenotypic variability, unknown long-term evolution, CFTR testing and pregnancy termination 4) a proposal for the assessment of potential barriers to the implementation and dissemination of the produced documents to health care professionals involved in the care of pwCFTR-RD and a process to monitor the implementation of the CFTR-RD recommendations; 5) clinical trials investigating the efficacy of CFTR modulators in CFTR-RD and how endpoints and outcomes might be adapted to the heterogeneity of these disorders.

Utility, benefits, and risks of newborn genetic screening carrier reports for families

Background

Newborn genetic screening (NBGS) based on next-generation sequencing offers enhanced disease detection and better detection rates than traditional newborn screening. However, challenges remain, especially around reporting the NBGS carrier results. Therefore, we aimed to investigate the NBGS carrier parents' views on NBGS and NBGS reports in China.

Methods

We distributed a survey querying demographic information, knowledge and perceptions of NBGS, the impact of NBGS on a total of 2930 parents, and their decision-making to parents of newborns reported as carriers in NBGS in Nanjing, China in 2022.

Results

The average age of the survey respondents was 30.7 years (standard deviation = 3.6). Most (68.38%) felt informed about NBGS, especially women, the highly educated, and high earners. Nearly all (98.74%) saw NBGS as crucial for early disease detection, with 73.18% believing it positively impacts their future. However, 19.16% felt it might cause anxiety, especially among the less educated. Concerns included potential discrimination due to exposed genetic data and strained family ties. Many suggested NBGS coverage by medical insurance to ease financial burdens.

Conclusions

Through our study, we gained insights into parents' perspectives and concerns regarding the NBGS carrier result reporting, thus providing relevant information for further refinement and clinical promotion of the NBGS project.

Standards for the care of people with cystic fibrosis (CF): A timely and accurate diagnosis

There is considerable activity with respect to diagnosis in the field of cystic fibrosis (CF). This relates primarily to developments in newborn bloodspot screening (NBS), more extensive gene analysis and improved characterisation of CFTR-related disorder (CFTR-RD). This is particularly pertinent with respect to accessibility to variant-specific therapy (VST), a transformational intervention for people with CF with eligible CFTR gene variants. This advance reinforces the need for a timely and accurate diagnosis. In the future, there is potential for trials to assess effectiveness of variant-specific therapy for CFTR-RD. The guidance in this paper reaffirms previous standards, clarifies a number of issues, and integrates emerging evidence. Timely and accurate diagnosis has never been more important for people with CF.

Diagnostic and Communication Challenges in Cystic Fibrosis Newborn Screening

As of December 2009, cystic fibrosis (CF) newborn screening (NBS) is performed in all 50 US states and the District of Columbia. Widespread implementation of CF newborn screening (CFNBS) in the US and internationally has brought about new and varied challenges. Immunoreactive trypsinogen (IRT) remains the first, albeit imperfect, biomarker used universally in the screening process. Advances in genetic testing have provided an opportunity for newborn screening programs to add CFTR sequencing tiers to their algorithms. This in turn will enable earlier identification of babies with CF and improve longer-term outcomes through prompt treatment and intervention. CFTR sequencing has led to the ability to identify infants with CF from diverse ethnic and racial backgrounds more equitably while also identifying an increasing proportion of infants with inconclusive diagnoses. Using the evolution of the New York State CF newborn screening program as a guide, this review outlines the basic steps in a universal CF newborn screening program, considers how to reduce bias, highlights challenges, offers guidance to address these challenges and provides recommendations for future consideration.

An Insight into Indonesia's Challenges in Implementing Newborn Screening Programs and Their Future Implications

Due to high entry barriers, countries might find it daunting to implement the NBS program, especially those just trying to start it. This review aims to discuss Indonesia's barriers that hinder newborn screening (NBS) implementation while discussing the future implications. Literature in Pubmed and Google Scholar was scoured with keywords such as "Newborn Screening", "Neonatal Screening", "Indonesia", "Asia Pacific", "Barriers", and "Challenges". We also searched for relevant references in those published articles. Grey literature, such as state regulations, informative webinars on the topics by experts regarding current situations, and press releases by the Indonesian Minister of Health (MoH), was also searched. Newborn screening is no longer considered just a laboratory test but an array of well-harmonized systems that must be orchestrated well. Some of the barriers Indonesia faces in implementing NBS are a lack of prevalence data, ethical issues, infrastructure, cost-benefit analysis, logistical issues, government support, patient issues, a lack of commitments, and a lack of healthcare workers, specialization, and training. Government support with professional advocates and support groups, proper infrastructure, and a single-payer system for NBS programs are necessary to accelerate NBS programs in Indonesia.

Refinement of newborn screening for cystic fibrosis with next generation sequencing

BACKGROUND

Newborn screening for cystic fibrosis (CF) has been underway universally in the United States for more than a decade, as well in most European countries, and algorithms have been evolving throughout this period with quality improvement projects as immunoreactive trypsinogen (IRT) determinations alone have been transformed to a 2-tier strategy with DNA analyses.

OBJECTIVE

To apply next generation sequencing (NGS) as a screening method to expand the DNA tier and identify substantially more variants in the CF transmembrane conductance regulator (CFTR) gene to enhance sensitivity and equity while minimizing incidental findings.

DESIGN

Sequential evaluation and improvement plan in three phases using algorithm modifications coupled to statewide follow up and analysis of screening outcomes.

RESULTS

After demonstrating feasibility in the first phase, we studied an IRT/NGS algorithm that included CFTR Variants with Varying Clinical Consequences (VVCCs). This revealed a high identification of CF patients with 2-variants detected through screening, but for every CF case there were 1.4 with CF metabolic syndrome/CF screen positive, inconclusive diagnosis (CRMS/CFSPID). This led us to a third phase of improvement in which the VVCCs were eliminated except for R117H, resulting in 94% 2-variant detection of patients and 0.44:1 ratio of CRMS/CFSPID to CF.

CONCLUSION

NGS can be used with IRT as an effective method of identifying infants at risk for CF without an appreciable increase in detection of carriers. Its potential added value includes facilitating equity, enhancing sensitivity and detecting more CF patients with 2-variants during the screening process.

Immunoreactive Trypsinogen in Infants Born to Women with Cystic Fibrosis Taking Elexacaftor–Tezacaftor–Ivacaftor

Most people with cystic fibrosis (CF) are diagnosed following abnormal newborn screening (NBS), which begins with measurement of immunoreactive trypsinogen (IRT) values. A case report found low concentrations of IRT in an infant with CF exposed to the CF transmembrane conductance regulator (CFTR) modulator, elexacaftor–tezacaftor–ivacaftor (ETI), in utero. However, IRT values in infants born to mothers taking ETI have not been systematically assessed. We hypothesized that ETI-exposed infants have lower IRT values than newborns with CF, CFTR-related metabolic syndrome/CF screen positive, inconclusive diagnosis (CRMS/CFSPID), or CF carriers. IRT values were collected from infants born in Indiana between 1 January 2020, and 2 June 2022, with ≥1 CFTR mutation. IRT values were compared to infants born to mothers with CF taking ETI followed at our institution. Compared to infants identified with CF (n = 51), CRMS/CFSPID (n = 21), and CF carriers (n = 489), ETI-exposed infants (n = 19) had lower IRT values (p < 0.001). Infants with normal NBS results for CF had similar median (interquartile range) IRT values, 22.5 (16.8, 30.6) ng/mL, as ETI-exposed infants, 18.9 (15.2, 26.5). IRT values from ETI-exposed infants were lower than for infants with abnormal NBS for CF. We recommend that NBS programs consider performing CFTR variant analysis for all ETI-exposed infants.

Practice resource-focused revision: Standardized pedigree nomenclature update centered on sex and gender inclusivity: A practice resource of the National Society of Genetic Counselors

This focused revision builds on the expert opinions from the original publications of 'Recommendations for human standardized pedigree nomenclature' published in 1995 and updated in 2008. Our review of medical publications since 2008 did not identify any fundamental systematic alternative pedigree nomenclature. These findings attest to the relevance of most of the nomenclature with the critical exception of the nomenclature used to denote sex assigned at birth and gender. While we are not recommending the creation of any new pedigree symbols, a major focus of this publication is clarification of the use of symbols and language in the description of the distinction between sex and gender, with a view to ensuring safe and inclusive practice for people who are gender-diverse or transgender. In addition, we recommend modifications to the way that carrier status is depicted. Our goal is to respect individual differences and identities while maintaining biologically, clinically, and genetically meaningful information.

Psychosocial Issues Related to Newborn Screening: A Systematic Review and Synthesis

Genomic advances have contributed to a proliferation of newborn screening (NBS) programs. Psychosocial consequences of NBS have been identified as risks to these public health initiatives. Following PRISMA guidelines, this systematic review synthesizes findings from 92 evidence-based, peer-reviewed research reports published from 2000 through 2020 regarding psychosocial issues associated with NBS. Results describe parents' knowledge of and attitudes towards NBS, reactions to and understanding of positive NBS results, experiences of communication with health providers, decisions about carrier testing, and future pregnancies. Findings also explain the impact of positive NBS results on parent-child relationships, child development, informing children about carrier status, family burden, quality of life, and disparities. In conclusion, psychosocial consequences of receiving unexpected neonatal screening results and unsolicited genetic information remain significant risks to expansion of NBS. Findings suggest that risks may be mitigated by improved parent NBS education, effective communication, individualized genetic counseling, and anticipatory developmental guidance. Clinicians need to take extra measures to ensure equitable service delivery to marginalized subpopulations. Future investigations should be more inclusive of culturally and socioeconomically diverse families and conducted in low-resource countries. Providing these countries with adequate resources to develop NBS programs is an essential step towards achieving international health equity.

Parental Preferences about Policy Options Regarding Disclosure of Incidental Genetic Findings in Newborn Screening: Using Videos and the Internet to Educate and Obtain Input

Our objective was to develop and test a new approach to obtaining parental policy guidance about disclosure of incidental findings of newborn screening for cystic fibrosis (CF), including heterozygote carrier status and the conditions known as CFTR-related metabolic syndrome (CRMS) and/or cystic fibrosis screen positive inconclusive diagnosis, CFSPID. The participants were parents of infants up to 6 months old recruited from maternity hospitals/clinics, parent education classes and stores selling baby products. Data were collected using an anonymous, one-time Internet-based survey. The survey introduced two scenarios using novel, animated videos. Parents were asked to rank three potential disclosure policies-Fully Informed, Parents Decide, and Withholding Information. Regarding disclosure of information about Mild X (analogous to CRMS/CFSPID), 57% of respondents ranked Parents Decide as their top choice, while another 41% ranked the Fully Informed policy first. Similarly, when considering disclosure of information about Disease X (CF) carrier status, 50% and 43% gave top rankings to the Fully Informed and Parents Decide policies, respectively. Less than 8% ranked the Withholding Information policy first in either scenario. Data from value comparisons suggested that parents believed knowing everything was very important even if they became distressed. Likewise, parents preferred autonomy even if they became distressed. However, when there might not be enough time to learn everything, parents showed a slight preference for deferring decision-making. Because most parents strongly preferred the policies of full disclosure or making the decision, rather than the withholding option for NBS results, these results can inform disclosure policies in NBS programs, especially as next-generation sequencing increases incidental findings.

Non-Invasive Detection of a De Novo Frameshift Variant of STAG2 in a Female Fetus: Escape Genes Influence the Manifestation of X-Linked Diseases in Females

Background: We report on a 20-week-old female fetus with a diaphragmatic hernia and other malformations, all of which appeared after the first-trimester ultrasound. Methods and Results: Whole trio exome sequencing (WES) on cell-free fetal DNA (cff-DNA) revealed a de novo frameshift variant of the X-linked STAG2 gene. Loss-of-function (LoF) STAG2 variants cause either holoprosencephaly (HPE) or Mullegama–Klein–Martinez syndrome (MKMS), are de novo, and only affect females, indicating male lethality. In contrast, missense mutations associate with milder forms of MKMS and follow the classic X-linked recessive inheritance transmitted from healthy mothers to male offspring. STAG2 has been reported to escape X-inactivation, suggesting that disease onset in LoF females is dependent on inadequate dosing for at least some of the transcripts, as is the case with a part of the autosomal dominant diseases. Missense STAG2 variants produce a quantity of transcripts, which, while resulting in a different protein, leads to disease only in hemizygous males. Similar inheritance patterns are described for other escapee genes. Conclusions: This study confirms the advantage of WES on cff-DNA and emphasizes the role of the type of the variant in X-linked disorders.

COVID-19 in a pregnant cystic fibrosis carrier with myasthenia gravis: A case report

A 16-year-old primigravida was diagnosed with COVID-19 in her second trimester. She decompensated quickly and had to be admitted to hospital and intubated. She was diagnosed with a fetal demise after being intubated and neurology suspected myasthenia gravis due to neurologic symptoms. Due to pan-sinusitis and increased mucus secretion, cystic fibrosis screening was ordered. After she was extubated, cervical ripening and induction was performed with eventual vaginal delivery without maternal complications. Myasthenia gravis and cystic fibrosis carrier status were confirmed after the patient was discharged.

•

Cystic fibrosis carrier status may increase the risk for severe COVID-19.

•

COVID-19 and myasthenia gravis in pregnancy may change treatment options.

•

Cystic fibrosis screening may be recommended to improve maternal outcomes.