Weighing the evidence for newborn screening for early-infantile Krabbe disease

Newborn Screening for Krabbe Disease: Status Quo and Recommendations for Improvements

Krabbe disease (KD) is part of newborn screening (NBS) in 11 states with at least one additional state preparing to screen. In July 2021, KD was re-nominated for addition to the federal Recommended Uniform Screening Panel (RUSP) in the USA with a two-tiered strategy based on psychosine (PSY) as the determinant if an NBS result is positive or negative after a first-tier test revealed decreased galactocerebrosidase activity. Nine states currently screening for KD include PSY analysis in their screening strategy. However, the nomination was rejected in February 2023 because of perceived concerns about a high false positive rate, potential harm to newborns with an uncertain prognosis, and inadequate data on presymptomatic treatment benefit or harm. To address the concern about false positive NBS results, a survey was conducted of the eight NBS programs that use PSY and have been screening for KD for at least 1 year. Seven of eight states responded. We found that: (1) the use of PSY is variable; (2) when modeling the data based on the recommended screening strategy for KD, and applying different cutoffs for PSY, each state could virtually eliminate false positive results without major impact on sensitivity; (3) the reason for the diverse strategies appears to be primarily the difficulty of state programs to adjust screening algorithms due to the concern of possibly missing even an adult-onset case following a change that focuses on infantile and early infantile KD. Contracts with outside vendors and the effort/cost of making changes to a program's information systems can be additional obstacles. We recommend that programs review their historical NBS outcomes for KD with their advisory committees and make transparent decisions on whether to accept false positive results for such a devastating condition or to adjust their procedures to ensure an efficient, effective, and manageable NBS program for KD.

A qualitative assessment of parental experiences with false-positive newborn screening for Krabbe disease

Numerous US states have implemented newborn screening for Krabbe disease (Krabbe NBS) as a result of legislative state mandates. While healthcare provider opinions toward Krabbe NBS have been documented, few studies have explored parental experiences and opinions regarding Krabbe NBS. Eleven families, who received a false-positive Krabbe NBS result and received genetic counseling at an institution in central Ohio, were consented to participate in semistructured interviews. Interviews explored parents' experiences throughout the NBS process and ascertained their opinions regarding Krabbe NBS. Three major themes emerged from thematic analysis: (1) improved understanding of the NBS process from a parent perspective, (2) the role of healthcare provider communication, and (3) the value of Krabbe NBS. Parents saw value in Krabbe NBS, despite many disclosing emotional distress and uncertainty throughout the NBS process. Parent experiences throughout the NBS process varied widely. Due to the expressed emotional distress, further research assessing effective communication during the NBS process is warranted. The researchers suggest additional NBS education for non-genetics healthcare providers (i.e., nurses or primary care physicians) and further participation of genetic counselors in the NBS process may benefit families with a positive Krabbe NBS result.

Identifying and overcoming barriers to harmonize newborn screening programs through consensus strategies

The benefits of newborn screening (NBS) programs have been widely demonstrated after more than 50 years since first established. NBS enables the detection of the disease before the child shows clinical symptoms, allowing clinicians to act early and facilitating appropriate interventions to prevent or improve adverse outcomes. Delay or lack of medical intervention in these infants may lead to developmental delay, severe disability, or premature death. NBS programs have grown exponentially both in the number of diseases screened and in complexity, creating controversy. New technological advances, as well as the emergence of new therapies that require early disease detection, have allowed for the inclusion of new diseases in NBS screening programs. However, different countries and even different regions have in turn adopted very diverse strategies and diagnostic algorithms when it comes to NBS. There are many factors responsible for these differences, such as the health care system, available funds, local politics, professional groups, and others that depend on the position taken by policymakers. These differences in NBS have led to discrepancies in detection opportunities between countries or regions, which has led to many varied attempts to harmonize NBS programs but not all have been equally satisfactory. Some countries have achieved good results, but always within their borders. Therefore, there are still many differences between NBS programs at the international level that must be overcome. These advances have also brought considerable uncertainty regarding ethical aspects and balance between benefits and harms. For this reason, and so that the situation of disparity in the global NBS programs can be minimized, health authorities must work to develop uniform criteria for decision-making and to take a further step toward harmonization. To do so, it is necessary to identify the crucial factors that lead to the adoption of different NBS programs worldwide, in order to analyze their influence and find ways to overcome them.

Survey of quality of life, phenotypic expression, and response to treatment in Krabbe leukodystrophy

OBJECTIVES

To develop a quality of life (QOL) survey for Krabbe disease (KD), and to thereby improve understanding of its phenotypic expression and response to treatment.

METHODS

The survey, the Leukodystrophy Quality of Life Assessment (LQLA) and the Vineland Adaptive Behavior Scales were co-administered to 33 patients or their caretakers. These included the phenotypes of early infantile KD (EIKD; 0-6 months old at onset), late infantile cases (LIKD; 7-12 months old at onset), and cases that emerged after 12 months old, late onset (LOKD). The sample included cases with and without stem cell transplantation (SCT). Reliability and concurrent validity were assessed for overall and subscale scores. Analysis of variance tested differences in QOL between phenotypes and transplant groups (none, pre-, post-symptom).

RESULTS

Good concurrent validity with the Vineland was shown for total, communication, daily activity, social, and motor scales and good reliability was observed. LOKD cases had better communication skills than either EIKD or LIKD and better overall QOL than EIKD. Analyses of individual items showed that communication items, mostly, contributed significantly to phenotype differences. Presymptomatic SCT significantly improved QOL compared to postsymptomatic SCT or no treatment. Presymptomatically treated patients had near-normal total scores.

CONCLUSIONS

The LQLA is valid and reliable. Despite small sample size, phenotypic demarcation was determined to be due mainly to differences in communication skills. There was a relative enhancement of QOL in LOKD patients, and in those who had presymptomatic SCT. These results apply to the current controversy about recommendations for newborn screening for this condition.

Health utilities and parental quality of life effects for three rare conditions tested in newborns

BACKGROUND

Measurement of health utilities is required for economic evaluations. Few studies have evaluated health utilities for rare conditions; even fewer have incorporated disutility that may be experienced by caregivers. This study aimed to (1) estimate health utilities for three rare conditions currently recommended for newborn screening at the state or federal level, and (2) estimate the disutility, or spillover, experienced by parents of patients diagnosed with a rare, heritable disorder.

METHODS

A stated-preference survey using a time trade-off approach elicited health utilities for Krabbe disease, phenylketonuria, and Pompe disease at varying stages (mild, moderate, severe) and onset of disease symptoms (infancy, childhood, and adulthood). We recruited respondents from a nationally representative community sample (n = 862). Respondents valued disease specific health states in three consecutive question frames: (1) adult health state (> = 18 years of age), (2) child health state (< 18 years of age), and (3) as a parent of a child with a condition (parent spillover state). Corresponding mean utilities were calculated for plausible disease states in adulthood and childhood. Mean disutility was estimated for parental spillover. Predictors of utilities were evaluated using a negative binomial regression model.

RESULTS

More severe conditions and infant health states received lower estimated utility and greater estimated disutility among parents. Conditions with the lowest estimated health utilities were severe infantile Pompe disease (0.40, CI: 0.34-0.46) and infantile Krabbe disease (0.37, CI: 0.32-0.43). Disutility was evident for all conditions evaluated (range: 0.07-0.19).

CONCLUSIONS

Rare childhood conditions are associated with substantial estimated losses in quality of life. Evidence of disutility among parents further warrants the inclusion of spillover effects in cost-effectiveness analyses. Continued research is needed to assess and measure the effects of childhood disease from a family perspective.

Consensus guidelines for newborn screening, diagnosis and treatment of infantile Krabbe disease

BACKGROUND

Krabbe disease is a rare neurodegenerative genetic disorder caused by deficiency of galactocerebrosidase. Patients with the infantile form of Krabbe disease can be treated at a presymptomatic stage with human stem cell transplantation which improves survival and clinical outcomes. However, without a family history, most cases of infantile Krabbe disease present after onset of symptoms and are ineligible for transplantation. In 2006, New York began screening newborns for Krabbe disease to identify presymptomatic cases. To ensure that those identified with infantile disease received timely treatment, New York public health and medical systems took steps to accurately diagnose and rapidly refer infants for human stem cell transplantation within the first few weeks of life. After 11 years of active screening in New York and the introduction of Krabbe disease newborn screening in other states, new information has been gained which can inform the design of newborn screening programs to improve infantile Krabbe disease outcomes.

FINDINGS

Recent information relevant to Krabbe disease screening, diagnosis, and treatment were assessed by a diverse group of public health, medical, and advocacy professionals. Outcomes after newborn screening may improve if treatment for infantile disease is initiated before 30 days of life. Newer laboratory screening and diagnostic tools can improve the speed and specificity of diagnosis and help facilitate this early referral. Given the rarity of Krabbe disease, most recommendations were based on case series or expert opinion.

CONCLUSION

This report updates recommendations for Krabbe disease newborn screening to improve the timeliness of diagnosis and treatment of infantile Krabbe disease. In the United States, several states have begun or are considering Krabbe disease newborn screening. These recommendations can guide public health laboratories on methodologies for screening and inform clinicians about the need to promptly diagnose and treat infantile Krabbe disease. The timing of the initial referral after newborn screening, the speed of diagnostic confirmation of infantile disease, and the transplantation center's experience and ability to rapidly respond to a suspected patient with newly diagnosed infantile Krabbe disease are critical for optimal outcomes.

Can psychosine and galactocerebrosidase activity predict early-infantile Krabbe's disease presymptomatically?

Krabbe's disease (KD) is a fatal neurodegenerative disorder, with the early-infantile form (EIKD) defined by onset of symptoms before age 6 months. Early and highly accurate identification of EIKD is required to maximize benefits of hematopoietic stem cell transplantation treatment. This study investigates the potential for accurate prediction of EIKD based on a novel newborn screening (NBS) tool developed from two biomarkers, galactocerebrosidase (GALC) enzyme activity and galactosylsphingosine concentration (psychosine [PSY]). Normative information about PSY and GALC, derived from distinct samples of normal newborns, was used to develop the novel diagnostic tool. Bivariate normal limits (BVNL) were constructed, assuming a multivariate normal distribution of natural logarithms of GALC and PSY of normal newborns. The (lnGALC, lnPSY) points for newborns in various "abnormal groups," including one group of infants who subsequently suffered EIKD, were plotted on a graph of BVNL. The points for all EIKD patients fell outside of BVNL (100% sensitivity). In a simulation study to compare the false-positive rate of existing univariate methods of diagnosis with our new BVNL-based method, we generated 100 million normal newborn data points. All fell within BVNL (i.e., zero false positives), whereas 5,682 false positives were observed when applying a two-tiered univariate method of the type suggested in the literature. These results suggest that (lnGALC, lnPSY) BVNLs will allow highly accurate prediction of EIKD, whereas two-tiered univariate approaches will not. Redevelopment of the BVNL based on GALCs and PSYs measured on a common large sample of normal newborns is required for NBS use. © 2016 Wiley Periodicals, Inc.

Perspective on innovative therapies for globoid cell leukodystrophy

Globoid cell leukodystrophy (GLD), or Krabbe's disease, is a lysosomal storage disorder resulting from deficiency of the lysosomal hydrolase galactosylceramidase. The infantile forms are characterized by a unique relentless and aggressive progression with a wide range of neurological symptoms and complications. Here we review and discuss the basic concepts and the novel mechanisms identified as key contributors to the peculiar GLD pathology, highlighting their therapeutic implications. Then, we evaluate evidence from extensive experimental studies on GLD animal models that have highlighted fundamental requirements to obtain substantial therapeutic benefit, including early and timely intervention, high levels of enzymatic reconstitution, and global targeting of affected tissues. Continuous efforts in understanding GLD pathophysiology, the interplay between various therapies, and the mechanisms of disease correction upon intervention may allow advancing research with innovative approaches and prioritizing treatment strategies to develop more efficacious treatments. © 2016 Wiley Periodicals, Inc.

Newborn screening for Krabbe's disease

Live newborn screening for Krabbe's disease (KD) was initiated in New York on August 7, 2006, and started in Missouri in August, 2012. As of August 7, 2015, nearly 2.5 million infants had been screened, and 443 (0.018%) infants had been referred for followup clinical evaluation; only five infants had been determined to have KD. As of August, 2015, the combined incidence of infantile KD in New York and Missouri is ∼1 per 500,000; however, patients who develop later-onset forms of KD may still emerge. This Review provides an overview of the processes used to develop the screening and followup algorithms. It also includes updated results from screening and discussion of observations, lessons learned, and suggested areas for improvement that will reduce referral rates and the number of infants defined as at risk for later-onset forms of KD. Although current treatment options for infants with early-infantile Krabbe's disease are not curative, over time treatment options should improve; in the meantime, it is essential to evaluate the lessons learned and to ensure that screening is completed in the best possible manner until these improvements can be realized. © 2016 Wiley Periodicals, Inc.

Psychosine, a marker of Krabbe phenotype and treatment effect

Newborn screening (NBS) for Krabbe disease, a rare neurodegenerative disorder caused by deficient galactocerebrosidase (GALC) enzyme activity, has recently been implemented in a number of US states. However, the spectrum of phenotypic manifestations associated with deficient GALC activity complicates the management of screen-positive newborns and underscores the need to identify clinically relevant biomarkers. Earlier studies with a small number of patients identified psychosine, a substrate of the GALC enzyme, as a potential biomarker for Krabbe disease. In this study, we provide, for the first time, longitudinal data on dried blood spot (DBS) psychosine concentrations in different Krabbe disease phenotypes for both untreated patients and those treated with hematopoietic stem cell transplantation (HSCT). Our cohort included patients previously identified by NBS to be at high risk to develop Krabbe disease. Substantially elevated DBS psychosine concentration during the newborn period was found to be a highly specific marker for infantile Krabbe disease. This finding supports the use of DBS psychosine concentration as a second-tier NBS test to aid in the identification of patients who require urgent evaluation for HSCT. In addition, longitudinal assessments showed that both natural disease progression and treatment with HSCT were associated with decreases in DBS psychosine concentrations. Based on these findings we provide recommendations for the interpretation of psychosine concentrations in DBS specimens collected during the first year of life. Future studies should aim to better delineate the relationship between DBS psychosine concentration and disease onset in patients with later-onset forms of Krabbe disease.

Newborn Screening for Lysosomal Storage Disorders

Newborn screening is one of the most important public health initiatives to date, focusing on the identification of presymptomatic newborn infants with treatable conditions to reduce morbidity and mortality. The number of screening conditions continues to expand due to advances in screening technologies and the development of novel therapies. Consequently, some of the lysosomal storage disorders are now considered as candidates for newborn screening, although many challenges including identification of late-onset phenotypes remain. This review provides a critical appraisal of the current state of newborn screening for lysosomal storage disorders.

Evidence for improved survival in postsymptomatic stem cell-transplanted patients with Krabbe's disease

Krabbe's disease (KD) is a severe neurodegenerative disorder affecting white matter in the brain and peripheral nerves. Transplantation of hematopoietic stem cells (HSCT), although not curative, has been shown to extend survival and alleviate neurodevelopmental symptoms when treatment precedes the onset of symptoms. Existing evidence, although not tested statistically, seems clearly to show that postsymptomatic transplantation does not improve neurodevelopmental outcomes. The impact of postsymptomatic HSCT treatment on survival, however, is an open question. This study uses a KD registry to examine the effect of HSCT on survival of symptomatic KD patients. Sixteen transplanted patients were matched by age of onset to 68 nontransplanted patients. The potential confounding effect of age of onset was, therefore, avoided. To quantify the effect of HSCT over time, we used Cox regression analysis, and we observed a sustained and nearly 2.2-fold risk of death from KD in patients who were not transplanted relative to those who were transplanted (one-tailed P = 0.0365; 95% lower bound = 1.07). The improvement of survival resulting from HSCT did not appear to depend on the age of symptom onset. Thus, these results establish a long-term, quantitative benefit of HSCT even in patients who are already experiencing symptoms. They also provide a benchmark for improved survival that can be used for potential new treatments for KD. © 2016 Wiley Periodicals, Inc.

Phenotypic variability of Krabbe disease across the lifespan

Krabbe disease (galactocerebrosidase deficiency) is an inherited leukodystrophy that results in severe neurological defects due to altered myelination. Classically, disease onset is within the first year of life. Juvenile and adult-onset cases may have less classic presentations, making diagnosis difficult and often delayed. Here, we review the literature to demonstrate the hetereogeneity of presenting symptoms across all age groups. We also discuss diagnostic approach, emphasizing variation in biochemical, functional, and genetic results among Krabbe phenotypes. Better understanding of the various Krabbe disease phenotypes is critical to facilitate timely diagnosis and appropriate treatment of this clinically heterogeneous disorder.

Variabilité phénotypique dans la maladie de Krabbe au cours de la vie du patient. La maladie de Krabbe (déficit en galactocérébrosidase) est une leukodystrophie héréditaire qui donne lieu à des déficits neurologiques sévères dus à un trouble de la myélinisation. Chez les cas dont la présentation est classique, la maladie débute au cours de la première année de vie. Si la maladie commence chez un adolescent ou un adulte, le mode de présentation peut-ětre moins classique, ce qui rend le diagnostic difficile et souvent tardif. Nous analysons les articles traitant du sujet pour démontrer l'hétérogénéité des symptômes au moment de la première consultation et ceci dans tous les groupes d'âge. Nous discutons également de l'approche diagnostique en mettant l'emphase sur la variation des résultats biochimiques, fonctionnels et génétiques des différents phénotypes dans la maladie de Krabbe. Une meilleure compréhension des différents phénotypes est cruciale pour faciliter un diagnostic précoce et un traitement approprié de cette maladie dont le mode de présentation clinique est hétérogène.

Should states adopt newborn screening for early infantile Krabbe disease?

The published experience to date regarding implementing NBS for EIKD has been dramatically enhanced by the data presented in this issue by Orsini et al. Although much has been written about the potential harms to individuals with an abnormal NBS for EIKD who do not have EIKD, several commentators have also asked whether screening provides a benefit when it leads to early identification of the disorder. Orsini and colleagues’ data suggest that the state-mandated, multimillion-dollar NBS program for EIKD in New York has failed to provide significant benefit to children with EIKD. Indeed, in addition to the potential harm to families receiving false-positive test results, NBS for EIKD appears to have resulted in a reduction in survival in individuals who have the disease. The data from the New York program suggest that NBS for EIKD should be abandoned, pending the development of improved screening or therapies shown to confer both survival and quality-of-life benefits over supportive care. The results of this experience suggest that research efforts should be focused on improving presymptomatic treatment outcomes in children identified by NBS prior to the redeployment of mandatory presymptomatic screening.

Newborn screening for Krabbe disease in New York State: the first eight years' experience

PURPOSE

Krabbe disease (KD) results from galactocerebrosidase (GALC) deficiency. Infantile KD symptoms include irritability, progressive stiffness, developmental delay, and death. The only potential treatment is hematopoietic stem cell transplantation. New York State (NYS) implemented newborn screening for KD in 2006.

METHODS

Dried blood spots from newborns were assayed for GALC enzyme activity using mass spectrometry, followed by molecular analysis for those with low activity (≤12% of the daily mean). Infants with low enzyme activity and one or more mutations were referred for follow-up diagnostic testing and neurological examination.

RESULTS

Of >1.9 million screened, 620 infants were subjected to molecular analysis and 348 were referred for diagnostic testing. Five had enzyme activities and mutations consistent with infantile KD and manifested clinical/neurodiagnostic abnormalities. Four underwent transplantation, two are surviving with moderate to severe handicaps, and two died from transplant-related complications. The significance of many sequence variants identified is unknown. Forty-six asymptomatic infants were found to be at moderate to high risk for disease.

CONCLUSIONS

The positive predictive value of KD screening in NYS is 1.4% (5/346) considering confirmed infantile cases. The incidence of infantile KD in NYS is approximately 1 in 394,000, but it may be higher for later-onset forms.

Public Perceptions of the Benefits and Risks of Newborn Screening

BACKGROUND

Growing technological capacity and parent and professional advocacy highlight the need to understand public expectations of newborn population screening.

METHODS

We administered a bilingual (French, English) Internet survey to a demographically proportional sample of Canadians in 2013 to assess preferences for the types of diseases to be screened for in newborns by using a discrete choice experiment. Attributes were: clinical benefits of improved health, earlier time to diagnosis, reproductive risk information, false-positive (FP) results, and overdiagnosed infants. Survey data were analyzed with a mixed logit model to assess preferences and trade-offs among attributes, interaction between attributes, and preference heterogeneity.

RESULTS

On average, respondents were favorable toward screening. Clinical benefits were the most important outcome; reproductive risk information and early diagnosis were also valued, although 8% disvalued early diagnosis, and reproductive risk information was least important. All respondents preferred to avoid FP results and overdiagnosis but were willing to accept these to achieve moderate clinical benefit, accepting higher rates of harms to achieve significant benefit. Several 2-way interactions between attributes were statistically significant: respondents were willing to accept a higher FP rate for significant clinical benefit but preferred a lower rate for moderate benefit; similarly, respondents valued early diagnosis more when associated with significant rather than moderate clinical benefit.

CONCLUSIONS

Members of the public prioritized clinical benefits for affected infants and preferred to minimize harms. These findings suggest support for newborn screening policies prioritizing clinical benefits over solely informational benefits, coupled with concerted efforts to avoid or minimize harms.

Ethical and policy issues in newborn screening of children for neurologic and developmental disorders

Genetic testing for neurologic and developmental disorders spans the spectrum from universal newborn screening for conditions like phenylketonuria to diagnostic testing for suspected genetic conditions, to predictive genetic testing for childhood-onset conditions. Given that virtually all children in the United States undergo genetic screening in the newborn period, this article focuses on 3 actual case studies of neurologic and developmental disorders that have been included or proposed for inclusion in newborn screening programs: Duchenne muscular dystrophy (a neuromuscular disorder), Krabbe disease (a neurodegenerative disorder), and fragile X syndrome (a neurodevelopmental disorder).

Newborn screening for lysosomal storage disorders

Every newborn in the U.S. is screened for at least 29 disorders, where evidence suggests that early detection is possible and beneficial. With new or improved treatment options and development of high-throughput screening tests, additional conditions have been proposed for inclusion in newborn screening programs. Among those are several lysosomal storage disorders that have been evaluated in limited pilot studies or that are already included in a few national or international newborn screening programs. These conditions include Pompe disease, Niemann-Pick type A/B disease, Fabry disease, Krabbe disease, Mucopolysaccharidoses types I and II, and Gaucher disease. Here, we review the current state of newborn screening for these lysosomal storage disorders.

Innovative treatments for lysosomal diseases

Striking therapeutic advances for lysosomal diseases have harnessed the biology of this organelle and illustrate its central rôle in the dynamic economy of the cell. Further Innovation will require improved protein-targetting or realization of therapeutic gene- and cell transfer stratagems. Rescuing function before irreversible injury, mandates a deep knowledge of clinical behaviour as well as molecular pathology – and frequently requires an understanding of neuropathology. Whether addressing primary causes, or rebalancing the effects of disordered cell function, true therapeutic innovation depends on continuing scientific exploration of the lysosome. Genuine partnerships between biotech and the patients affected by this extraordinary family of disorders continue to drive productive pharmaceutical discovery.

The evolution of blood-spot newborn screening

Over 50 years after the introduction of a blood-spot newborn screening test using the bacterial-inhibition assay (BIA), blood-spot newborn screening has evolved into complex public service scientific programmes. For several decades, many patients with phenylketonuria (PKU), congenital hypothyroidism (CH), cystic fibrosis (CF) and hemoglobinopathy disorders have benefited from early intervention across the world. In the last 20 years, there have been great changes in laboratory techniques and high-throughput data handling meaning that a huge spectrum of disorders can be identified from an increasing population. This coupled with the fact that there are an increasing number of therapies for specific rare disorders mean that health services may become inundated with complex and expensive demands in the future. Some of these issues have been realised in the implementation of multiplex assay such as electrospray tandem mass spectrometry (MSMS) programmes but will be much more exaggerated if genomic sequencing screening becomes a reality. In this context, the core-principles for implementation of newborn screening tests remain as important today as they have in the past when new tests are considered as part of the blood-spot screening programme.

Newborn screening for lysosomal storage disorders and other neuronopathic conditions

Newborn screening (NBS) is a public health program aimed at identifying treatable conditions in presymptomatic newborns to avoid premature mortality, morbidity, and disabilities. Currently, every newborn in the Unites States is screened for at least 29 conditions where evidence suggests that early detection is possible and beneficial. With new or improved treatment options and development of high-throughput screening tests, additional conditions have been proposed for inclusion into NBS programs. Among those are several conditions with a strong neuronopathic component. Some of these conditions have already been added to a few national and international screening programs, whereas others are undergoing pilot studies to determine the test performance metrics. Here, we review the current state of NBS for 13 lysosomal storage disorders, X-adrenoleukodystrophy, Wilson disease, and Friedreich ataxia.

Parental permission for pilot newborn screening research: guidelines from the NBSTRN

There is broad recognition of the need for population-based research to assess the safety and efficacy of newborn screening (NBS) for conditions that are not on current panels. However, prospective population-based research poses significant ethical, regulatory, and logistical challenges. In the context of NBS, there have been a variety of approaches that address parental decision-making in pilot studies of new screening tests or conditions. This article presents an ethical and legal analysis of the role of parental permission by the Bioethics and Legal Work Group of the Newborn Screening Translational Research Network created under a contract from the National Institute of Child Health and Human Development to the American College of Medical Genetics and Genomics. Circumstances are outlined in which a waiver of documentation of permission or a waiver of permission may be ethically and legally appropriate in the NBS context. These guidelines do not constitute American Academy of Pediatrics policy.

Development of clinical guidelines for inborn errors of metabolism: commentary

This is one of an occasional series of articles commenting on trends, advances, and challenges in understanding and treating inborn errors of metabolism (IEMs). Previously, we have called attention to the critical lack of a clinical trial infrastructure to routinely evaluate new therapies for IEMs and the adverse effect of this deficit (Vockley and Vockley, 2010 [1]). In this article, we highlight the role of therapeutic guidelines in implementing best practice for IEMs and the processes used to generate them. Current conventions for evidence-based guidelines are best applied to studies involving significantly more subjects than is feasible for IEMs, and can lead to relative weak-appearing recommendations when applied to rare disorders. We propose a guideline development process that maintains the use of conventional methodologies but adapts to unique features and inherent difficulties dealing with rare conditions such as IEMs. Such guidelines will consist of a hybrid between evidence and consensus based processes. Implementation of these recommendations and subsequent therapeutic guidelines for IEMs provides an opportunity to define current knowledge as well as starting points for future clinical trials.

Expanding newborn screening for lysosomal disorders: opportunities and challenges

Newborn screening (NBS), since its implementation in the 1960s, has traditionally been successful in reducing mortality and disability in children with a range of different conditions. Lysosomal storage disorders (LSD) are a heterogeneous group of inherited metabolic diseases that result from lysosomal dysfunction. Based on available treatment and suitable screening methods, the LSDs that are considered for NBS generally include Fabry, Gaucher, Krabbe, MPSI, MPSII, MPSV, Metachromatic leukodystrophy, Niemann-Pick, and Pompe. Utilizing traditional and expanded criteria for consideration of NBS leads to a set of fundamental questions that need to be explored when considering the opportunities and challenges of adding LSDs to NBS panels.

Dangerous and expensive screening and treatment for rare childhood diseases: the case of Krabbe disease

Public policy surrounding newborn screening is in flux. New technology allows more screening for more diseases at lower cost. Traditional criteria for target diseases have been criticized by leading health policymakers. The example of newborn screening for Krabbe disease highlights many of the dilemmas associated with population-based screening programs. Krabbe is difficult to diagnose, variable in its natural history, and does not always respond to treatment. The only available treatment is hematopoietic stem cell transplantation, which is expensive, risky, and of uncertain efficacy. This article analyzes the debate about Krabbe as an example of the sorts of debates that will likely arise for many more diseases over the next decade. I conclude that pilot programs in pioneer states should be carefully evaluated before testing for Krabbe is universalized.

Newborn screening for lysosomal storage diseases: an ethical and policy analysis

The traditional focus of newborn screening (NBS) is testing infants for medical conditions like phenylketonuria (PKU) that may cause significant morbidity or mortality unless treatment is initiated early. Although the Wilson and Jungner criteria were not designed specifically for NBS, the public health screening criteria have been used, with some modifications, to justify what conditions are included in a universal NBS panel. These criteria are being challenged by platform technologies like tandem mass spectrometry (MS/MS) that allow for the identification of numerous conditions on a single sample because they identify many conditions and variants simultaneously, some of which meet and others which fail to meet the criteria. In this manuscript, I evaluate three lysosomal storage diseases included in this multiplex screening test-Pompe disease, Fabry disease, and Krabbe disease. I show that they fail to meet some of the critical Wilson and Jungner criteria and thus are not ready for inclusion in universal NBS panels. Rather, screening for these conditions should only be performed in the research context with institutional review board approval and parental permission.

Array CGH improves detection of mutations in the GALC gene associated with Krabbe disease

BACKGROUND

Krabbe disease is an autosomal recessive lysosomal storage disorder caused by mutations in the GALC gene. The most common mutation in the Caucasian population is a 30-kb deletion of exons 11 through 17. There are few other reports of intragenic GALC deletions or duplications, due in part to difficulties detecting them.

METHODS AND RESULTS

We used gene-targeted array comparative genomic hybridization (CGH) to analyze the GALC gene in individuals with Krabbe disease in whom sequence analysis with 30-kb deletion analysis identified only one mutation. In our sample of 33 cases, traditional approaches failed to identify two pathogenic mutations in five (15.2%) individuals with confirmed Krabbe disease. The addition of array CGH deletion/duplication analysis to the genetic testing strategy led to the identification of a second pathogenic mutation in three (9.1%) of these five individuals. In all three cases, the deletion or duplication identified through array CGH was a novel GALC mutation, including the only reported duplication in the GALC gene, which would have been missed by traditional testing methodologies. We report these three cases in detail. The second mutation remains unknown in the remaining two individuals (6.1%), despite our full battery of testing.

CONCLUSIONS

Analysis of the GALC gene using array CGH deletion/duplication testing increased the two-mutation detection rate from 84.8% to 93.9% in affected individuals. Better mutation detection rates are important for improving molecular diagnosis of Krabbe disease, as well as for providing prenatal and carrier testing in family members.

Screening for disease in the newborn: the evidence base for blood-spot screening

This paper reviews the evidence of benefit resulting from newborn screening in Australia as well as for some of those disorders not yet included in the Australian panels, and discusses briefly disorders under active consideration for inclusion in the screening panels.There is solid evidence of benefit from newborn screening for phenylketonuria, congenital hypothyroidism, cystic fibrosis, and overall for the disorders included in tandem mass spectrometry screening. There is also some evidence of benefit for several disorders not screened for in Australia, including congenital adrenal hyperplasia. Harms resulting from screening include anxiety related to false positive results; adverse effects of unwarranted treatment for mild variants; unwanted genetic information; and the costs (opportunity costs) of screening. For well-run programs these harms are relatively small.Screening could become more effective with the development of good systems for rational consideration of disorders to be included, with the extended use of second tier testing to reduce the false positive rate, and with research on the most effective way to deal with mild variants. The most important aspect of increasing effectiveness is the full integration of the screening program, diagnostic laboratories, and the clinical service. This is already in place in Australasia.

Public support for neonatal screening for Pompe disease, a broad-phenotype condition

Background

Neonatal screening for Pompe disease has been introduced in Taiwan and a few U.S. states, while other jurisdictions including some European countries are piloting or considering this screening. First-tier screening flags both classic infantile and late-onset Pompe disease, which challenges current screening criteria. Previously, advocacy groups have sometimes supported expanded neonatal screening more than professional experts, while neutral citizens' views were unknown. This study aimed to measure support for neonatal screening for Pompe disease in the general public and to compare it to support among (parents of) patients with this condition. The study was done in the Netherlands, where newborns are not currently screened for Pompe disease. Newborn screening is not mandatory in the Netherlands but current uptake is almost universal.

Methods

A consumer panel (neutral group) and (parents of) patients with Pompe disease (Pompe group) were sent information and a questionnaire. Responses were analyzed of 555 neutral and 58 Pompe-experienced informants who had demonstrated sufficient understanding.

Results

87% of the neutral group and 88% of the Pompe group supported the introduction of screening (95% CI of difference -10 to 7%). The groups were similar in their moral reasoning about screening and acceptance of false positives, but the Pompe-experienced group expected greater benefit from neonatal detection of late-onset disease. Multivariate regression analysis controlling for demographics confirmed that approval of the introduction of screening was independent of having (a child with) Pompe disease. Furthermore, respondents with university education, regardless of whether they have (a child with) Pompe disease, were more likely to be reluctant about the introduction of screening than those with less education, OR for approval 0.29 (95% CI 0.18 to 0.49, p < 0.001).

Conclusions

This survey suggests a rather high level of support for newborn screening for Pompe disease, not only among those who have personal experience of the disease but also among the general public in the Netherlands. Optional screening on the basis of informed parental consent is probably unrealistic, underlining the need for new guidelines to help policymakers in their consideration of newborn screening for broad phenotype conditions.

Krabbe disease: clinical, biochemical and molecular information on six new patients and successful retrospective diagnosis using stored newborn screening cards

PURPOSE

To present clinical, biochemical and molecular information on six new clinically diagnosed Krabbe disease patients and assess the sensitivity of retrospective galactocerebrosidase measurement in their newborn screening samples.

METHODS

Medical records were reviewed. Galactocerebrosidase activity was measured in leukocytes and, retrospectively, in the patients' newborn screening cards (stored for 1.4 to 13.5 years). GALC gene mutation analysis was performed.

RESULTS

Five patients with Krabbe disease, one of whom also had hydrocephalus, became symptomatic during infancy. A sixth patient presented with seizures and developmental regression at age two and had a protracted disease course. Galactocerebrosidase activity in leukocytes ranged from 0.00 to 0.20 nmol/h/mg protein. Low galactocerebrosidase activity (range: 3.2% to 11.1% of the daily mean), consistent with Krabbe disease, was detected in each of the newborn screening samples. GALC molecular analysis identified six previously unreported mutations and two novel sequence variants.

CONCLUSION

Our cases highlight the clinical variability of Krabbe disease. Galactocerebrosidase activity in newborn dried blood spots is a highly sensitive test, even when samples have been stored for many years. The high frequency of private mutations in the GALC gene may limit the use of genetic information for making treatment decisions in the newborn period.

Ethical issues in genetics

Genetic disorders are caused by abnormalities in genes and chromosomes and for the most part have implications for family members, affecting such matters as confidentiality and disclosure to third parties. Genetic testing can be not only diagnostic but also predictive, raising issues of the need for pre-test counselling, protection of children from unwanted testing, and most importantly, the imprecision of interpretation of future risk. The rise in availability of direct-to-consumer testing is a fresh cause for concern, as are the new possibilities in reproductive medicine. New technologies and the falling cost of whole genome sequencing ensure that ethics will be a prominent concern for clinical genetics.

Genetic screening

Current approaches to genetic screening include newborn screening to identify infants who would benefit from early treatment, reproductive genetic screening to assist reproductive decision making, and family history assessment to identify individuals who would benefit from additional prevention measures. Although the traditional goal of screening is to identify early disease or risk in order to implement preventive therapy, genetic screening has always included an atypical element-information relevant to reproductive decisions. New technologies offer increasingly comprehensive identification of genetic conditions and susceptibilities. Tests based on these technologies are generating a different approach to screening that seeks to inform individuals about all of their genetic traits and susceptibilities for purposes that incorporate rapid diagnosis, family planning, and expediting of research, as well as the traditional screening goal of improving prevention. Use of these tests in population screening will increase the challenges already encountered in genetic screening programs, including false-positive and ambiguous test results, overdiagnosis, and incidental findings. Whether this approach is desirable requires further empiric research, but it also requires careful deliberation on the part of all concerned, including genomic researchers, clinicians, public health officials, health care payers, and especially those who will be the recipients of this novel screening approach.

Newborn screening: how are we travelling, and where should we be going?

In general, newborn screening is now a highly successful enterprise. The introduction of tandem mass spectrometry in the mid-1990s changed the pace of screening, raising its profile and increasing its relevance to a wider range of health professionals. The clinical effectiveness is not in doubt for some conditions, but is lacking for others. Evaluation has major difficulties for the rarer disorders and has been sadly neglected. Partly because clinical effectiveness has not been enthusiastically addressed, but also because of undue caution on the part of regulators, who often seem to ignore available evidence, there are huge differences in the adoption of screening programmes in different jurisdictions. New treatments, especially mutation-specific treatments, and technological advances in diagnostic testing are being rapidly developed, and this will further change the face of newborn screening and probably magnify these differences. The challenges will be considerable, especially with the increasing availability of DNA testing at modest cost. It is likely that there will be pressure to change the aims of newborn screening to encompass "personalised medicine". We must all prepare in a thoughtful way for these future challenges.