Parents' experience with positive newborn screening results for cystic fibrosis

Psychosocial Impact of False-Positive Newborn Screening Results: A Scoping Review

Psychosocial consequences of false-positive results following newborn bloodspot screening have been identified as a potential risk to this highly successful public health initiative. A scoping review was undertaken in October 2023 underpinned by the Arksey and O'Malley framework. Twenty-four papers were included in the review, many of which focused on cystic fibrosis. The results indicated that impact of false-positive results is variable; some studies suggest false-positive results have the potential to result in negative sequelae including increased stress and changes in parental perceptions of their child, while others suggest these impacts are transient and, in some instances, may even lead to positive outcomes. Further evidence is needed to ensure the representation of other conditions included in newborn bloodspot screening and to support strategies to overcome potential negative sequela.

Single-centre prospective evaluation of the first 5 years of cystic fibrosis newborn screening in Germany

Background

In 2016, nationwide cystic fibrosis newborn screening (CFNS) was newly implemented in Germany, using an immunoreactive trypsin/pancreatitis-associated protein/DNA screening algorithm that differs from most other nationwide screening programmes.

Methods

We analysed real-life feasibility of the confirmation process with respect to our pre-specified procedural objectives. These included overall accuracy through false-negative and false-positive results, effectiveness of the Bavarian tracking system, and accuracy of Macroduct and Nanoduct sweat conductivity compared with quantitative chloride determination. All consecutive CFNS-positive newborns assigned to our CF centre and born between 1 September 2016 and 31 August 2021 (n=162) were included.

Results

The German CFNS was feasible at our CF centre as all procedural objectives were met. The positive predictive value (PPV) of positive CFNS was low (0.23) and two initially negatively screened children were later diagnosed with CF. The tracking system was highly efficient with a 100% tracking rate. The Macroduct and Nanoduct systems had comparable success rates (93.2% versus 95.9%). Importantly, conductivity via Macroduct was more accurate than via Nanoduct (zero and four false-positive newborns, respectively).

Conclusions

CF confirmation diagnostics of neonates in a certified regional CF centre was well managed in daily routine. The PPV of the German CFNS needs to be improved, e.g. by extending the DNA analysis within the screening algorithm and by increasing the number of variants tested. The Bavarian tracking system can serve as a successful model for other tracking systems. We preferred the Macroduct system because of its more accurate sweat conductivity readings.

Parental Experiences of Genetic Testing

Genetic testing is increasingly used in clinical practice in the neonatal period, including in NICUs. This testing may have psychological consequences for parents. To best support families, neonatal clinicians should be aware of the various ways in which parents view and respond to genetic testing. In this review, we summarize research on the parental experience of having a newborn infant undergo genetic testing.

[Newborn blood spot screening (NBS) in Germany : Status quo and presentation of a concept for further development]

Newborn screening from dried blood spots (NBS) is a highly effective secondary prevention measure that has been established for many years. Against the background of the inclusion of "new diseases" that meet the screening criteria, a concept for the further advancement of NBS was developed on behalf of the GKV-Spitzenverband. This was based on a systematic literature review and a survey of the status quo of NBS in Germany using quantitative and qualitative methods.It is essential for the success of NBS that all newborns affected by a target disease are diagnosed and treated at an early stage and that the harm to be expected with each screening (e.g., due to false positive findings) is kept as low as possible. This requires the organisation of screening in the sense of an integrated programme through central coordination with standardised structures, continuous quality management and digitalisation in line with data protection requirements.Although in general NBS is being implemented successfully in Germany, the research project presented here also reveals weaknesses and a need for action. Proposals and recommendations were compiled in a concept paper, which shows approaches for further development of NBS in line with the current state of research in consideration of changing demands on the infrastructure and processes in the health system. This review article summarises the challenges, current status and possible solutions for the central topics of the concept paper.

Parents' experience of the communication process of positivity at newborn screening for metabolic diseases: A qualitative study

BACKGROUND

The process of receiving a communication of positivity for metabolic diseases at expanded newborn screening (ENBS) is extremely articulated, involves a variety of actors (parents, maternal and child departments, clinical centres and laboratories) and is open to a variety of outcomes from false positive to true positive cases. Receiving communication of positivity can be highly stressful for parents and requires an adequate communication process to give clear and reliable information without causing excessive worry. This qualitative study describes the parents' experience of receiving a communication of positivity to metabolic diseases at ENBS, and their assessment of the quality of the communication process and steps, with the main aim to identify the process' strengths and weaknesses and to advance tailored recommendations to improve the communication process.

METHOD

Fourteen in-depth, semi-structured phone interviews were conducted with parents whose children resulted positive to the ENBS. As part of the ENBS communication process, parents received a first phone call communication of positivity and a second in-person communication at metabolic clinical centres (MCC). The framework analysis method was used to organize the data and identify emerging themes.

RESULTS

Parents were largely dissatisfied with the quality and depth of the information received and with the way the healthcare staff delivered the first communication phone call, which failed to create a caring, empathic and safe setting. Many parents tried to reduce the uncertainty by searching online information or consulting with other providers. Nevertheless, the majority of parents described the in-person visit at MCC as clear, welcoming and reassuring.

CONCLUSION

More efforts are needed to improve the quality of the communication process of the ENBS. Guidelines, recommendations and standard scripts to communicate positivity are needed along with programmes and educational resources to train tailored communication skills.

Communicating a Positive Result at Newborn Screening and Parental Distress

The assumption of this study is strictly connected to the need to focus and to know more about the impact on the psychological state of the parents whose newborn babies get a positive result at Expanded Newborn Screening (ENS). As clinical experience shows us, this aspect seems to have a potentially lasting resonance on the way the disease will be managed and handled in the family, leading to potential negative effects and repercussions on the child's wellbeing and on the quality of life within the family. On the basis of this and on the evidence emerging from a review of the literature, this study aims to investigate and objectify possible distress indicators elicited at the moment of the communication of a positive result at ENS. Questionnaires containing the Beck Depression Inventory-II, the State-Trait Anxiety Inventory-Y, and the Short Form 36 Health Survey tests were administered to the parents of 87 newborns who received positive results at ENS. The parents of 32 babies expressed the presence of discomfort potentially related to the communication of a positive result at ENS.

Is Our Newborn Screening Working Well? A Literature Review of Quality Requirements for Newborn Blood Spot Screening (NBS) Infrastructure and Procedures

Newborn screening using dried blood spots (NBS) is widely acknowledged as a highly successful procedure in secondary prevention. For a number of congenital disorders, severe disability or death are impressively prevented by early detection and early treatment through NBS. However, as with any other screening, NBS can also cause harm, and the principle that "the overall benefits of screening should outweigh the harms" must be considered when introducing and implementing NBS programmes. This publication compiles the results of a systematic literature research on requirements for NBS infrastructure and procedures which was conducted as part of a research project on the quality and shortcomings of the NBS pathway in Germany. The compilation contains the requirements and recommendations for realising the principle of "maximise benefits and minimise harms" in relevant NBS pathway components such as parental education and information, coverage, timeliness, laboratory quality assurance, follow-up of abnormal results, confirmatory diagnostics, documentation, and evaluation. The results reflect the complexity of NBS infrastructure, and thus, they illustrate the importance of considering and implementing NBS as a well-coordinated public health programme with continuous quality management. Special attention should be paid to the perspectives of parents and families. Some NBS issues can substantially benefit from digital instruments or international cooperation. The literature review presented here has contributed to a concept of proposals for the advancement of NBS in Germany, and despite different settings, it may as well be of interest for other countries to achieve the best possible course and outcome of NBS for each child.

German newborn screening for Cystic fibrosis: Parental perspectives and suggestions for improvements

PURPOSE

Cystic fibrosis (CF) was added to the German newborn bloodspot screening (NBS) panel in 2016. This study assesses parental perceptions of CF-NBS and confirmatory testing.

METHODS

Prospective questionnaire-based survey administered to parents of children with positive CF-NBS over 40 months after initiation of CF-NBS in Southwest Germany. Parental perceptions were compared to results from Bavaria and Switzerland.

RESULTS

Questionnaires with 29 standardized questions were sent to 343 families with children born between October 2016 and January 2020. A total of 178 (51.9%) replied. Although required by law, only a minority were informed about CF-NBS by a physician. The information provided about NBS was sufficient for 78% of parents. Regarding the information about positive CF-NBS, 52.9% were satisfied but the majority expressed negative emotions (89.5%). While most of these were resolved after confirmatory diagnostics, 17% of parents of children with false-positive CF-NBS and 66.7% of children confirmed with CF remained anxious. Waiting time for sweat testing was >3 days in 56.1%, considerably longer than in more centralized screening systems. Parents who waited for a maximum of 3 days were significantly more satisfied. 70.7% of parents were satisfied with the information given during confirmatory diagnostics and 91.4% were satisfied with participating in CF-NBS.

CONCLUSIONS

CF-NBS stands in high regard with parents. Smooth organization, timely initiation of confirmatory testing, and professional communication are most important to limit parental anxiety. A more centralized system of confirmatory diagnostics appears advantageous in several regards as it reduces time from positive NBS to final diagnosis and increases parental satisfaction.

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.

Communication of an Abnormal Metabolic New-Born Screening Result in The Netherlands: The Parental Perspective

In the Netherlands, abnormal New-Born Screening (NBS) results are communicated to parents by the general practitioner (GP). Good communication and consequential trust in professionals is of the utmost importance in the treatment of phenylketonuria (PKU). The aim of this study was to assess parental satisfaction regarding the communication of an abnormal NBS result for PKU in the Netherlands. An email containing the link to a web-based questionnaire was sent by the Dutch PKU Association to their members. Responses to open questions were categorized, data of both open and closed questions were analysed with descriptive statistics and the Chi-Square test using SPSS. Out of 113 parents of a child with PKU (born between 1979 and 2020), 68 stated they were overall unsatisfied with the first communication of the NBS result. Seventy-five parents indicated that wrong or no information about PKU was given. A significant decrease was found in the number of parents being contact by their own GP over the course of 40 years (p < 0.05). More than half of all parents were overall unsatisfied with the first communication of the abnormal NBS result for PKU. Further research on how to optimize communication of an abnormal NBS results is necessary.

Being affiliated to a cystic fibrosis centre is important for parents' everyday life

Aim

Newborn screening represents a paradigm shift in the treatment of children with cystic fibrosis. This study aimed to explore parents' everyday life experiences from the time of diagnosis and in the following months.

Methods

Narrative interviews were conducted at Aarhus University Hospital, Denmark, with parents (mothers = 15 and fathers =14) of 15 term‐born children with a mean age of 2 weeks (range 1–3.5 weeks). Participant observation and field notes were used to complement interview data. The analysis was inspired by Kvale and Brinkmann.

Results

Three themes were identified. First, on diagnosis, a profound difference in parents' experience was observed depending on whether the diagnosis was communicated by a medical doctor from the cystic fibrosis team or by a paediatrician from another hospital. Second, during the initial meetings and subsequent relationships with the cystic fibrosis team, the knowledge and calmness exhibited by the doctors and nurses were very valuable. Third, regarding everyday life after the diagnosis, most parents described experiencing anxiety and concern for their child's future.

Conclusion

The parents' experiences highlighted essential elements that should be implemented to optimise the patient care pathway as they are fundamental to parents' ability to cope with the new living conditions.

Biotinidase Activity is Affected by Both Seasonal Temperature and Filter Collection Cards

This study set out to examine pre-analytical factors affecting the frequency of positive results in newborn screening for biotinidase deficiency. This investigation was prompted by an increase in the annual screen positive rate for biotinidase deficiency in Ontario from 2.65x10^-4 in 2016 to 6.57x10^-4 in 2017. Season and trend decomposition was used to separate seasonality from an underlying trend in the time series of biotindase activity measurements for the period 2014-01-12 to 2019-07-27 (n = 798,770). This analysis revealed a marked seasonal effect (winter = median + ⩽ 17 MRU, summer = mean - ⩽20 MRU) and a non-linear negative trend. Seasonal temperature was correlated with biotinidase results (Pearson's r = 0.79) but not with the observed negative trend (Pearson's r = 0.0025). Time series analysis of biotinidase results grouped by print lot of filter paper revealed that recently printed filter paper cards inhibit biotinidase and that this inhibition resolved over time. This study demonstrates that biotindase activity is inhibited by both increased seasonal temperature and collection on newly printed filter cards.

Geographical barriers to timely diagnosis of cystic fibrosis and anxiety level of parents during newborn screening in Turkey

BACKGROUND

Despite the availability of cystic fibrosis (CF) screening countrywide, diagnostic delay is still a crucial issue. The objectives of this study were to explore the stages of the NBS process, determine the risk factors associated with diagnostic delay and evaluate parent anxiety and experience throughout the process.

METHODS

This is a multicenter cross-sectional study. A questionnaire was completed by parents of newborns diagnosed with CF via NBS in 17 centers. Socio-demographic characteristics, parent knowledge and experiences related to NBS, sweat test availability in the region of residence, and time to the definitive CF diagnosis were assessed through this questionnaire. Parents' anxiety levels were evaluated through the State-Trait Anxiety Inventory scales 1 and 2. Delayed diagnosis (DD) was defined as a definite CF diagnosis beyond the 8th week of life. Predictors of delayed CF diagnosis were evaluated by univariate and multivariate analysis.

RESULTS

A total of 220 CF patients diagnosed via NBS were enrolled; 82 (37.3%) babies had DD. Multivariable analysis indicated that residence in the Southeast Anatolia region of Turkey (OR = 10.79, 95% CI = 2.37-49.2) was associated with a higher incidence of DD compared with other regions in Turkey. Of the total, 216 (98.1%) of the caregivers regarded the NBS program as useful and 180 (82%) reported high anxiety levels.

CONCLUSION

The organization of newborn screening should take into account regional and socio-cultural characteristics to improve the early diagnosis of CF and also reduce the anxiety level of parents.

Co-designing improved communication to parents of newborn bloodspot screening results (Preprint)

Background

Each year in England, almost 10,000 parents are informed of their child’s positive newborn bloodspot screening (NBS) results. This occurs approximately 2 to 8 weeks after birth depending on the condition. Communication of positive NBS results is a subtle and skillful task, demanding thought, preparation, and evidence to minimize potentially harmful negative sequelae. Evidence of variability in the content and the way the result is currently communicated has the potential to lead to increased parental anxiety and distress.

Objective

This study focused on the development of co-designed interventions to improve the experiences of parents receiving positive NBS results for their children and enhance communication between health care professionals and parents.

Methods

An experience-based co-design approach was used to explore experiences and co-design solutions with 17 health professionals employed in 3 National Health Service Trusts in England and 21 parents (13/21, 62% mothers and 8/21, 38% fathers) of 14 children recruited from the same 3 National Health Service Trusts. Experiences with existing services were gathered via semistructured interviews with health professionals. Filmed narrative interviews with parents were developed into a composite film. The co-design process identified priorities for improving communication of positive NBS results through separate parent and health professional feedback events followed by joint feedback events. In total, 4 interventions were then co-designed between the participants through a web-based platform.

Results

Parents and health professionals provided positive feedback regarding the process of gathering experiences and identifying priorities. Themes identified from the parent interviews included impact of initial communication, parental reactions, attending the first clinic appointment, impact of health professionals’ communication strategies and skills, impact of diagnosis on family and friends, improvements to the communication of positive NBS results, and parents’ views on NBS. Themes identified from the health professional interviews included communication between health professionals, process of communicating with the family, parent- and family-centered care, and availability of resources and challenges to effective communication. In response to these themes, 4 interventions were co-designed: changes to the NBS card; standardized laboratory proformas; standardized communication checklists; and an email or letter for providing reliable, up-to-date, condition-specific information for parents following the communication of positive NBS results.

Conclusions

Parents and health professionals were able to successfully work together to identify priorities and develop co-designed interventions to improve communication of positive NBS results to parents. The resulting co-designed interventions address communication at different stages of the communication pathway to improve the experiences of parents receiving positive NBS results for their children.

International Registered Report Identifier (IRRID)

RR2-10.1186/s40814-019-0487-5

Process evaluation of co-designed interventions to improve communication of positive newborn bloodspot screening results

OBJECTIVE

To implement and evaluate co-designed interventions to improve communication of positive newborn bloodspot screening results and make recommendations for future research and practice.

DESIGN

A process evaluation underpinned by Normalisation Process Theory.

SETTING

Three National Health Service provider organisations in England.

PARTICIPANTS

Twenty-four healthcare professionals (7 newborn screening laboratory staff and 24 clinicians) and 18 parents were interviewed.

INTERVENTIONS

Three co-designed interventions were implemented in practice: standardised laboratory proformas, communication checklists and an email/letter template.

PRIMARY OUTCOME MEASURES

Acceptability and feasibility of the co-designed interventions.

RESULTS

Auditing the implementation of these interventions revealed between 58%-76% of the items on the laboratory proforma and 43%-80% of items on the communication checklists were completed. Interviews with healthcare professionals who had used the interventions in practice provided positive feedback in relation to the purpose of the interventions and the ease of completion both of which were viewed as enhancing communication of positive newborn bloodspot screening results. Interviews with parents highlighted the perceived benefit of the co-designed interventions in terms of consistency, pacing and tailoring of information as well as providing reliable information to families following communication of the positive newborn bloodspot screening result. The process evaluation illuminated organisational and contextual barriers during implementation of the co-designed interventions in practice.

CONCLUSION

Variations in communication practices for positive newborn bloodspot screening results continue to exist. The co-designed interventions could help to standardise communication of positive newborn screening results from laboratories to clinicians and from clinicians to parents which in turn could improve parents' experience of receiving a positive newborn bloodspot screening result. Implementation highlighted some organisational and contextual barriers to effective adoption of the co-designed interventions in practice.

TRIAL REGISTRATION NUMBER

ISRCTN15330120.

"We needed this": perspectives of parents and healthcare professionals involved in a pilot newborn screening program for spinal muscular atrophy

BACKGROUND

Newborn screening (NBS) for spinal muscular atrophy (SMA) is a recognised model through which health outcomes can be improved. However, perspectives of parents and healthcare professionals (HCPs) involved in such programs are largely unknown.

METHODS

A pilot program for SMA ran from August 2018-July 2020. Using a mixed-methods convergent methodology, we used a self-administered questionnaire to understand parents' perceptions and psychological impact of the program from diagnosis to treatment. We thematically analysed successes/challenges encountered by HCPs and recommendations for service improvement from both participant groups.

FINDINGS

202,388 infants were screened for SMA and the perceptions of 44 parents and HCPs affected by a positive result in eighteen newborns was ascertained. Parents (n=29, 100%) were satisfied with NBS for SMA. Although screen-positive result was distressing for all parents, quality of life improved over time [CarerQoL-7D baseline median score 4 (SD=1.4) vs six-month median score 8 (SD=1.3), p<0.001)]. Challenges for HCPs included managing the time-critical nature of the pathway whilst remaining cognisant of limitations associated with the predictive screening test.

INTERPRETATION

Interpretation: NBS for SMA fulfils criteria for population-wide screening. Net benefits are acknowledged by stakeholders to optimise lifelong outcomes. Harms including psychological distress associated with a screen-positive result may be managed by targeted psychosocial support, information provision and a personalised model of care together strengthening healthcare systems.

FUNDING

The NSW Pilot NBS study was funded by Luminesce Alliance. Dr Kariyawasam received funding from the RTP Scholarship, University of New South Wales and The Freedman Family Foundation Scholarship, Sydney Children's Hospital Foundation.

Communicating cystic fibrosis newborn screening results to parents

The way results of cystic fibrosis (CF) newborn screening are communicated to parents is critical yet is done differently across the globe. We surveyed parents of 101 children in our tertiary London paediatric centre with a 48% response rate. Parental responses were as follows: 40/42 (95%) said the information could not have been given over the phone and 39/43 (91%) said they wanted both partners present; 27/42 (64%) said it was helpful having the health visitor also present; and 37/40 (92%) felt it was acceptable to wait until the next day for the sweat test. We have reduced the time from first contact to arriving in the home to 2-3 h.Conclusion: We believe that this survey backs up our approach of a home visit by a CF nurse specialist with the family's health visitor to break the news. This is challenging in the current COVID-19 pandemic. What is Known: • Breaking bad news can have a lasting impact on parents when not done the right way. • Giving results of cystic fibrosis (CF) newborn screening is done differently within the UK and around the world. What is New: • Our parental survey revealed that the majority (92%) believed this should be done face to face and not over the telephone. • There was a mixed response to whether the parents should be told the genotype (assuming the CF centre knew), and thus the CF diagnosis before the confirmatory sweat test was carried out.

Implementing a tracking system for confirmatory diagnostic results after positive newborn screening for cystic fibrosis-implications for process quality and patient care

Newborn screening for cystic fibrosis (CF-NBS) was introduced in Germany in 2016. Currently, systematic follow-up of positive CF-NBS results is not implemented or reimbursed in the NBS program. We investigated results of confirmatory testing over 24 months after implementation of CF-NBS for a large German NBS center before and after introduction of an active tracking system and performed a cost calculation for tracking. Results are compared with the federal state of Bavaria, where a centralized tracking system has been in place for many years. At the NBS center, 244 of 281,907 children had a positive CF-NBS result requiring diagnostic confirmation. Before implementation of a telephone tracking system, only 43% of confirmatory results were returned despite repeated written requests. The consecutive strategy including telephone tracking led to an increase of resolved cases to 84%. However, the centralized tracking system in Bavaria, assigning children with positive CF-NBS directly to a responsible CF-center, resolved 99% of cases. The calculated additional cost for a tracking system in Germany including telephone tracking is 1.20€ per newborn screened.Conclusion: The implementation of a tracking system achieves a distinct improvement in CF-NBS with justifiable costs. The effect can be limited by absence of centralized organization of confirmatory testing. What is Known: • Newborn screening for cystic fibrosis (CF-NBS) has been performed for many years in several countries worldwide • While many studies have focused on different CF-NBS strategies, the organization of confirmatory testing and process quality concerning returned information to the NBS center has so far received less attention. What is New: • The implementation of an active tracking system achieves a distinct improvement of clarified cases after positive CF-NBS with justifiable costs. • The effect of a tracking system can be limited by the absence of a centralized organization of confirmatory testing.

Psychological Impact of NBS for CF

Newborn screening for cystic fibrosis has resulted in diagnosis often before symptoms are recognised, leading to benefits including reduced disease severity, decreased burden of care, and lower costs. The psychological impact of this often unsought diagnosis on the parents of seemingly well children is less well understood. The time during which the screening result is communicated to families but before the confirmatory test results are available is recognised as a period of uncertainty and it is this uncertainty that can impact most on parents. Evidence suggests this may be mitigated against by ensuring the time between communication and confirmatory testing is minimized and health professionals involved in communicating positive newborn screening results and diagnostic results for cystic fibrosis to families are knowledgeable and able to provide appropriate reassurance. This is particularly important in the case of false positive results or when the child is given a Cystic Fibrosis Screen Positive, Inconclusive Diagnosis designation. However, to date, there are no formal mechanisms in place to support health professionals undertaking this challenging role, which would enable them to meet the expectations set out in specific guidance.

The Role of Extended CFTR Gene Sequencing in Newborn Screening for Cystic Fibrosis

There has been considerable progress in the implementation of newborn screening (NBS) programs for cystic fibrosis (CF), with DNA analysis being part of an increasing number of strategies. Thanks to advances in genomic sequencing technologies, CFTR-extended genetic analysis (EGA) by sequencing its coding regions has become affordable and has already been included as part of a limited number of core NBS programs, to the benefit of admixed populations. Based on results analysis of existing programs, the values and challenges of EGA are reviewed in the perspective of its implementation on a larger scale. Sensitivity would be increased at best by using EGA as a second tier, but this could be at the expense of positive predictive value, which improves, however, if EGA is applied after testing a variant panel. The increased detection of babies with an inconclusive diagnosis has proved to be a major drawback in programs using EGA. The lack of knowledge on pathogenicity and penetrance associated with numerous variants hinders the introduction of EGA as a second tier, but EGA with filtering for all known CF variants with full penetrance could be a solution. The issue of incomplete knowledge is a real challenge in terms of the implemention of NBS extended to many genetic diseases.