Population newborn screening for inherited metabolic disease: current UK perspectives

Clinical and Laboratory Markers of Hereditary Metabolic Diseases in Children of the First Half of Life

A significant contribution to the morbidity and mortality of children is due to hereditary pathology, which is manifested by high mortality. Aim of the research. To study the frequency of occurrence, structure and clinical and laboratory markers of hereditary metabolic diseases in children of the first half of the year with suspicion of this pathology. Materials and methods. A retrospective analysis of case histories (form No. 003/y) and a face-to-face examination of patients directed to blood tests by tandem mass spectrometry, from Surgery Unit No. 2 for Newborns and Premature Babies and from the Unit of Pathology of Newborns, (Ivano-Matryoninskaya City Children’s Clinical Hospital, Irkutsk). Results. In 2019, 21 children with suspected hereditary metabolic diseases were examined using the tandem mass spectrometry method in the above mentioned departments. All of them had at least one of the main clinical criteria for hereditary metabolic diseases: 67 % had hepatomegaly in combination with an increase in the level of liver enzymes, 43 % had a hereditary history and metabolic acidosis, 33 % showed a sudden deterioration after a period of normal development, 24 % had hypoglycemia, and 14 % had an abnormal urine or body odor, in 4.7 % of cases there was an increase in ketone bodies in the blood and (or) urine. All children identified from 3 to 7 additional criteria, which are indications for examination on the hereditary metabolic diseases. The results of the study revealed 5 children with hereditary metabolic diseases namely amino acid metabolism. 90 % of them had a burdened hereditary history, 100 % had a concomitant pathology – hepatitis and cholestatic lesions of the liver, anemia, an open oval window and others. Conclusion. Despite the obvious economic and medical significance of preclinical identification of patients with hereditary metabolic diseases, the screening problem contains many open questions that need to be addressed at all levels of the organization.

International differences in the evaluation of conditions for newborn bloodspot screening: a review of scientific literature and policy documents

Despite international adoption of newborn bloodspot screening (DBS), no two countries' screening programs are the same. This article aims to understand what factors influence DBS decision-making criteria and how conditions are assessed against them. In doing so, it offers unique insights into the international landscape of DBS. A systematic review on DBS criteria in scientific literature was first undertaken. Through this, five topics were identified for consideration when analyzing DBS decision-making. Using these five topics as a template, a side-by-side comparison was conducted on DBS in policy documents of eight countries. Programs are using different approaches to explore the same policy issues, including: the beneficiary of DBS, definition of criteria, the way conditions are assessed, level of evidence required, and recommendations after assessment. These differences have the potential to result in increased disparity across DBS internationally. Ultimately, governments need to decide on their role and develop an approach to DBS decision-making in line with this role. The analyses presented in this article highlight that despite programs' commonalities, no one 'DBS decision-making solution' exists. Understanding the different approaches to decision-making within the literature and policy settings, provides an objective starting point for structured decision-making approaches for DBS programs.

Benefits and burdens of newborn screening: public understanding and decision-making

In this article we review the literature regarding the public understanding of the potential benefits and burdens of expanded newborn bloodspot screening. We draw attention to broadened notions of benefit that go beyond early identification of asymptomatic individuals and interventions to reduce morbidity or mortality, and include benefits gained by families through knowledge that may facilitate life choices, as well as gains generated by avoiding diagnostic delays. We also reflect on burdens such as increasing false-positive results and parental anxiety, together with risks of overdiagnosis when the natural history of a condition is poorly understood. We conclude that expanded notions of benefit and burden bring with them implications for parental consent and confidentiality and the secondary use of bloodspots.

[Determination of normal acylcarnitine levels in a healthy pediatric population as a diagnostic tool in inherited errors of mitochondrial fatty acid beta-oxidation]

INTRODUCTION

Acylcarnitine measurement in blood is a useful test for the diagnosis of inherited errors of mitochondrial fatty acid beta-oxidation. However, there are few data in the literature on the reference ranges of the various acylcarnitines and on whether these reference ranges are age- or sex-dependent.

OBJECTIVES

To draw attention to inherited errors of mitochondrial fatty acid beta-oxidation and to establish reference acylcarnitine values in children.

PATIENTS AND METHODS

A total of 309 blood samples from healthy children divided into four age groups (group A: <1 month; group B: 1-12 months; group C: 1-7 years; group D: 7-18 years) were obtained and analyzed using tandem mass spectrometry.

RESULTS AND CONCLUSION

Reference acylcarnitine values in children are provided. No significant differences were found in relation to age or sex. Our results differ from those reported in the literature reviewed. Importantly, hydroxyacylcarnitines and glutaryl carnitine are absent when normal samples are processed. We review the literature on the main clinical and laboratory findings in mitochondrial fatty acid beta-oxidation deficiencies.

The cost-effectiveness of expanding newborn screening for up to 21 inherited metabolic disorders using tandem mass spectrometry: results from a decision-analytic model

OBJECTIVES

In 2005, in Ontario, Canada, newborns were only screened for phenylketonuria (PKU) and hypothyroidism. Tandem mass spectrometry (MS/MS) has since been implemented as a new screening technology because it can screen for PKU and many other diseases simultaneously. We estimated the cost-effectiveness of using this technology to expand the Ontario newborn screening program to screen for each disease independently and for hypothetical bundles of up to 21 metabolic diseases.

METHODS

We constructed a decision-analytic model to estimate the incremental costs and life-years of survival that can be gained by screening or changing screening technologies. Costs and health benefits were estimated for a cohort of babies born in Ontario in 1 year. Secondary sources and expert opinion were used to estimate the test characteristics, disease prevalence, treatment effectiveness, disease progression rates, and mortality. The London Health Sciences Centre Case Costing Initiative, the Ontario Health Insurance Plan Schedule, and the Ontario Drug Benefits plan formulary were used to estimate costs.

RESULTS

Changing screening technologies, from the Guthrie test to MS/MS, for PKU detection had an incremental cost of $5,500,000 per life-year (LY) gained. We identified no diseases for which the incremental cost of screening for just that disease was less than $100,000 per LY gained. The incremental costs of screening ranged from $222,000 (HMG-CoA lyase deficiency) to $142,500,000 (glutaric acidemia type II) per LY gained. Screening for a bundle of diseases including PKU and the 14 most cost-effective diseases to screen for cost less than $70,000 per LY gained, and the incremental cost-effectiveness of adding each of the 14 diseases to the bundle was less than $100,000 per LY gained. The incremental cost of adding the 15th most cost-effective disease was $309,400 per LY gained.

CONCLUSIONS

Early diagnosis and treatment of metabolic disease is important to reduce disease severity and delay or prevent the onset of the disease. Screening at birth reduces the morbidity, mortality, and social burden associated with the irreversible effects of disease on the population. Our analysis suggests that the cost-efficiencies gained by using MS/MS to screen for bundles of diseases rather than just one disease are sufficient to warrant consideration of an expanded screening program. It is, however, not cost-effective to screen for all diseases that can be screened for using this technology.

International perspectives on newborn screening

The development of electrospray tandem mass spectrometry (MS-MS) has greatly increased the number of diseases that can be detected by newborn blood-spot screening. Different countries are introducing the technology at different rates and for different disease panels. Current policies in the United Kingdom, Germany and the United States are taken as examples. In the United Kingdom, many laboratories are using MS-MS for routine screening for phenylketonuria but, except for those participating in a two-year pilot study of screening for medium-chain acyl-CoA dehydrogenase deficiency, are forbidden use MS-MS to screen for other disorders. In Germany there has been considerable experience of MS-MS screening for a wide range of diseases, but recently the Federal Ministry for Health and Social Security prescribed a much more restricted disease panel, with the instruction that any other diagnostic results are to be suppressed and not reported. By contrast, a recent report from the American College of Medical Genetics, still being debated, recommends screening procedures that will detect an extremely broad range of disorders, including some that are very rare or of unproven clinical significance. The lack of even broad concordance at the level of national policy is extremely disturbing. Though all discussion is nominally founded on the ten principles laid down by Wilson and Jungner in 1968, there seems no generally accepted way of using these principles, or derived criteria, as objective decision tools. Alternative, less categorical, approaches are needed: the disorders concerned are not homogeneous entities and there may be advantages to screening other than reducing morbidity or mortality.

Diagnosis and management of defects of mitochondrial beta-oxidation

PURPOSE OF REVIEW

At least 22 different inborn errors of metabolism affecting beta-oxidation in skeletal muscle and other tissues have been identified in the past 30 years. Early diagnosis and therapeutic diets offer the best chance for normal growth and development in most patients.

RECENT FINDINGS

Clinical heterogeneity has become the hallmark of defects in beta-oxidation. In many cases a correct diagnosis will only be made if these disorders are specifically considered and appropriate studies are obtained, since screening tests which detect other inborn errors of metabolism are often normal in patients with beta-oxidation defects. Dietary management provides the only opportunity for therapy in many cases, including carbohydrate supplements intended to provide more extended delivery of glucose to the bloodstream. Use of a novel odd chain fat supplement as an alternative fuel source in long chain fat metabolism defects offers promise of alleviating muscular symptoms not well controlled by diet. The introduction of expanded newborn screening will lead to the recognition of an increasing number of individuals with these disorders, placing greater demand for services on practitioners knowledgeable in their therapy. Study of the clinical outcome in these patients will provide a better understanding of defects of beta-oxidation.

SUMMARY

Clinical symptoms, diagnostic testing, and issues of newborn screening for this important group of disorders are discussed.

Cost-benefit analysis of universal tandem mass spectrometry for newborn screening

OBJECTIVE

To estimate potential costs and benefits of routinely using tandem mass spectrometry (MS/MS) to screen newborns for inborn errors of metabolism.

METHOD

Analysis of costs and benefits resulting from use of MS/MS in screening of 32 000 newborn infants using data from the Kaiser Permanente Medical Care Program of Northern California plus other published data.

SETTING

A large health maintenance organization.

RESULTS

In the base scenario, the cost per quality-adjusted life year saved by MS/MS screening was $5827; in the least favorable scenario, this cost was $11 419, and in the most favorable scenario, $736.

CONCLUSION

Costs per quality-adjusted life year saved by MS/MS screening for inborn errors of metabolism compare favorably with other mass screening programs, including those for breast and prostate cancer.

Very high compliance in an expanded MS-MS-based newborn screening program despite written parental consent

OBJECTIVES

In Bavaria, Germany, an expanded MS-MS-based newborn screening program was implemented in 1999. The coverage of new additional conditions and novelty of technology required introduction of written parental consent. Here we evaluated the influence of the consent procedure on compliance by systematic demographic tracking.

METHODS

Comprehensive information was provided for parents, professionals, and the public. Screening notifications were matched with all birth notifications on name and date of birth. Parents of children without screening notification were contacted and counseled.

RESULTS

Between August 1, 1999, and July 31, 2000, 123,284 children eligible for screening were born. Of these, 116,652 were matched successfully. Among 6,632 parents contacted, 2,516 (2%) did not respond. Three thousand thirty-four children were screened but the parents initially refused to participate in tracking. Five hundred ninety-four were screened outside the program. Four hundred eighty-eight untested newborns were identified. Three hundred twenty-five screening failures due to logistic problems were tested subsequently. Screening was definitely refused by the parents of 163 children (0.1% of target population).

CONCLUSIONS

With appropriate information provided and surveillance by tracking, high compliance with newborn screening can be achieved despite a written consent requirement.

Neonatal biochemical screening for disease

BACKGROUND

The practice of screening the neonatal population for certain diseases by biochemical testing of a dried blood spot is an established public health initiative in many countries. The diseases for which screening is done vary from region to region, based on ethnic, financial and political considerations. Criteria have been established to identify diseases suitable for neonatal screening.

DISEASES SCREENED

In Western countries, screening for phenylketonuria (PKU) and congenital hypothyroidism (CH) has been introduced throughout. Subsequently, cost-benefit analysis has confirmed the existence of a financial benefit. Other diseases screened for in some regions include galactosemia, aminoacidemias and organic acidemias, cystic fibrosis, congenital adrenal hyperplasia, biotinidase deficiency, hemoglobinopathies, glucose-6-phosphate dehydrogenase deficiency, and Duchenne muscular dystrophy, although in no case has a clear financial benefit been established.

CONCLUSIONS

Since the introduction of neonatal screening over 40 years ago, new methods have resulted in an increase in the number of diseases amenable to screening, better automation and greater specificity. Methods currently used include growth of an inhibited bacterial auxotroph (the original phenylalanine (phe) method of Dr. Robert Guthrie), spectrophotometry, fluorometry, immunoassay, and tandem mass spectrometry with electrospray ionization.

Neonatal screening for metabolic, endocrine, infectious, and genetic disorders. Current and future directions

There are good reasons to expect that future neonatal screening will expand both to include more disorders and to cover more of the global newborn population. Disorders for which neonatal screening will be given high priority in the health care field in the future are CH and PKU. Screening for CH is likely to expand faster than screening for PKU, especially in the developing world. In the future, screening for CAH will be practiced much more widely than today. Screening for CF is likely to qualify for routine neonatal screening in the future, especially if gene therapy becomes successful. Screening for infectious diseases is an area that is also developing rapidly. Which disorders to screen for neonatally will depend on a number of factors that are unique to each society, such as the prevalence, economy, and ethics. This must be realized when international guidelines are drafted. Technical development, which is of major importance for neonatal screening, includes MS-MS, different DNA techniques, and automation. The expansion of biomedical knowledge in a wide variety of fields will establish new grounds for neonatal screening.

Acute encephalopathy despite early therapy in a patient with homozygosity for E365K in the glutaryl-coenzyme A dehydrogenase gene

A patient with glutaric aciduria type I had an acute encephalopathic crisis despite early treatment. This report indicates that current therapeutic strategies may be insufficient for some high-risk patients and stresses the demand for new approaches in glutaric aciduria type I.