Harmonization of distributed multi-center analysis based on dried blood spot reference materials supporting the screening of neonatal inherited metabolic disorders

BACKGROUND

The standardization of quantification data is critical for ensuring the reliability and measurement traceability in the screening of neonatal inherited metabolic disorders. However, the availability of national certified reference materials is limited in China.

METHODS

In this study, we developed a series of dried blood spot (DBS) reference materials containing 9 amino acids (AA) and 10 acylcarnitines (AC) for neonatal screening. Four levels of the reference materials were measured with tandem mass spectrometry (MS/MS) by seven laboratories using different commercial In Vitro Diagnostic Device (IVD) kits. Then, 100 clinical samples were measured using both derivatization and non-derivatization methods by the same laboratory.

RESULTS

We found high homogeneity and stability at all levels of the reference materials, with the coefficient of variation (CV) of the analytes less than 15%. These reference materials can be used to assess the testing capabilities of different laboratories. Our test also revealed that the correction factors (CF) calculated by the reference materials, along with clinical samples, could increase the consistency for different kits.

CONCLUSION

The DBS reference materials proposed in this study provide reliability for the harmonization in multi-center analysis for the screening of neonatal inherited metabolic disorders. And applying our correction method for the screening could improve the data consistency of the DBS samples prepared by different methods.

Stability of Plasma Protein Composition in Dried Blood Spot during Storage

Dried blood spot (DBS) technology has become a promising utility for the transportation and storage of biological fluids aimed for the subsequent clinical analysis. The basis of the DBS method is the adsorption of the components of a biological sample onto the surface of a membrane carrier, followed by drying. After drying, the molecular components of the biosample (nucleic acids, proteins, and metabolites) can be analyzed using modern omics, immunological, or genomic methods. In this work, we investigated the safety of proteins on a membrane carrier by tryptic components over time and at different temperatures (+4, 0, 25 °C) and storage (0, 7, 14, and 35 days). It was shown that the choice of a protocol for preliminary sample preparation for subsequent analytical molecular measurements affects the quality of the experimental results. The protocol for preliminary preparation of a biosample directly in a membrane carrier is preferable compared to the protocol with an additional stage of elution of molecular components before the sample preparation procedures. It was revealed that the composition of biosamples remains stable at a temperature of −20 and +4 °C for 35 days of storage, and at +25 °C for 14 days.

Verification of a Blood-Based Targeted Proteomics Signature for Malignant Pleural Mesothelioma

BACKGROUND

We have verified a mass spectrometry (MS)-based targeted proteomics signature for the detection of malignant pleural mesothelioma (MPM) from the blood.

METHODS

A seven-peptide biomarker MPM signature by targeted proteomics in serum was identified in a previous independent study. Here, we have verified the predictive accuracy of a reduced version of that signature, now composed of six-peptide biomarkers. We have applied liquid chromatography-selected reaction monitoring (LC-SRM), also known as multiple-reaction monitoring (MRM), for the investigation of 402 serum samples from 213 patients with MPM and 189 cancer-free asbestos-exposed donors from the United States, Australia, and Europe.

RESULTS

Each of the biomarkers composing the signature was independently informative, with no apparent functional or physical relation to each other. The multiplexing possibility offered by MS proteomics allowed their integration into a single signature with a higher discriminating capacity than that of the single biomarkers alone. The strategy allowed in this way to increase their potential utility for clinical decisions. The signature discriminated patients with MPM and asbestos-exposed donors with AUC of 0.738. For early-stage MPM, AUC was 0.765. This signature was also prognostic, and Kaplan-Meier analysis showed a significant difference between high- and low-risk groups with an HR of 1.659 (95% CI, 1.075-2.562; P = 0.021).

CONCLUSIONS

Targeted proteomics allowed the development of a multianalyte signature with diagnostic and prognostic potential for MPM from the blood.

IMPACT

The proteomic signature represents an additional diagnostic approach for informing clinical decisions for patients at risk for MPM.

Inborn Errors of Metabolism in the Era of Untargeted Metabolomics and Lipidomics

Inborn errors of metabolism (IEMs) are a group of inherited diseases with variable incidences. IEMs are caused by disrupting enzyme activities in specific metabolic pathways by genetic mutations, either directly or indirectly by cofactor deficiencies, causing altered levels of compounds associated with these pathways. While IEMs may present with multiple overlapping symptoms and metabolites, early and accurate diagnosis of IEMs is critical for the long-term health of affected subjects. The prevalence of IEMs differs between countries, likely because different IEM classifications and IEM screening methods are used. Currently, newborn screening programs exclusively use targeted metabolic assays that focus on limited panels of compounds for selected IEM diseases. Such targeted approaches face the problem of false negative and false positive diagnoses that could be overcome if metabolic screening adopted analyses of a broader range of analytes. Hence, we here review the prospects of using untargeted metabolomics for IEM screening. Untargeted metabolomics and lipidomics do not rely on predefined target lists and can detect as many metabolites as possible in a sample, allowing to screen for many metabolic pathways simultaneously. Examples are given for nontargeted analyses of IEMs, and prospects and limitations of different metabolomics methods are discussed. We conclude that dedicated studies are needed to compare accuracy and robustness of targeted and untargeted methods with respect to widening the scope of IEM diagnostics.

Amino and organic acid analysis: Essential tools in the diagnosis of inborn errors of metabolism

Inborn errors of metabolism (IEMs) are a large class of genetic disorders that result from defects in enzymes involved in energy production and metabolism of nutrients. For every metabolic pathway, there are defects that can occur and potentially result in an IEM. While some defects can go undetected in one's lifetime, some have moderate to severe clinical consequences. In the latter case, the biochemical defect leads to accumulation of metabolites and byproducts that are toxic or interfere with normal biological function. Disorders of amino acid metabolism, organic acid metabolism and the urea cycle comprise a large portion of IEMs. Two essential tools required for the diagnosis of these categories of disorders are amino acid and organic acid profiling. Most all clinical laboratories offering metabolic testing perform amino acid analysis, while organic acid profiling is restricted to more specialized pediatric hospitals and reference laboratories. In this chapter, we will provide an overview of various methodologies employed for amino acid and organic acid profiling as well as specific examples to demonstrate how these techniques are applied in clinical laboratories for the diagnosis of IEMs.

Newborn screening for 3-hydroxy-3-methylglutaric aciduria using direct analysis in real-time mass spectrometry

A novel method utilizing ambient thermal desorption ionization with a direct analysis in real-time source integrated with mass spectrometry (DART-MS) was established and applied to the rapid analysis of 3-hydroxy-3-methylglutaric (3-HMG) acid in the neonatal urine. Instrument parameter settings were optimized to obtain high sensitive and accurate determination of 3-HMG acid. The use of helium gas heated to temperature of 400°C was observed to permit deprotonation, 3-HMG acid producing an abundant (M-H)^- (m/z 161) in the negative ion mode. The calibration curve was determined to be linear over the range of 0.05-5 mg/L, with the correlation coefficient r = 0.9988 and the relative standard deviations (n = 6) in the range of 1.5-11.8%. The limit of detection was 0.002 mg/L, and the limit of quantitation was 0.007 mg/L. The recoveries ranged from 88.0% to 123.1%. Four urine samples from patients and four simulated urine samples were investigated. The results of DART-MS were in agreement with the values determined using established methods at the hospitals. The proposed method demonstrated significant potential in the application of the high-throughput screening in newborn screening.

New Advances for Newborn Screening of Inborn Errors of Metabolism by Capillary Electrophoresis-Mass Spectrometry (CE-MS)

Expanded newborn screening of inborn errors of metabolism (IEM) based on tandem mass spectrometry (MS/MS) technology is one of the most successful preventative healthcare initiatives for presymptomatic diagnosis and treatment of rare yet treatable genetic diseases in the population. However, confirmatory testing of presumptive screen-positive cases is required using high efficiency separations for improved specificity in order to improve the positive predictive value (PPV) for certain classes of IEMs. Here, we describe recent advances using capillary electrophoresis-mass spectrometry (CE-MS) for reliable second-tier screening or confirmatory testing based on targeted analysis of amino acids, acylcarnitines, nucleosides, and other classes of polar metabolites associated with IEMs. Additionally, nontargeted metabolite profiling enables the identification of unknown biomarkers of clinical significance for other genetic diseases that are currently screened by bioassays and/or mutation panels, such as cystic fibrosis (CF). Noteworthy, CE-MS allows for resolution of isobaric/isomeric interferences without complicated sample handling that is ideal when analyzing volume-restricted biospecimens from neonates/infants, including dried blood spots and sweat specimens. New developments to improve concentration sensitivity, as well as enhance sample throughput and quality control for unambiguous confirmatory testing of IEMs will also be discussed when using multiplexed separations based on multisegment injection-CE-MS.

An Assessment of a Shortened Consent Form for the Storage and Research Use of Residual Newborn Screening Blood Spots

As state newborn screening programs develop approaches to parental permission for the storage and use of residual dried newborn screening samples, it is important to understand how the public comprehends the consent elements. Focus groups in Utah, California, and Michigan ( n = 7 groups, 69 participants) were conducted to evaluate the language on a shortened consent form. Outcomes from the analysis included barriers to conceptualizing biospecimen research, the overly cautious tone and awkwardness of the consent form, and perceptions of community versus individual benefit. This research offers insight on public response to, and comprehension of, commonly used consent language for the storage and use of dried blood spot research in a shortened consent form.

Effects of birth weight on profiles of dried blood amino-acids and acylcarnitines

Background

Birth weight influences profiles of dried blood amino-acids and acylcarnitines in newborn screening. This study aimed to define a more appropriate cut-off value to reduce the false positive rate and the number of recalled patients in newborn screening.

Methods

All babies who underwent newborn screening in our center were included; they were divided into groups by birth weight: 2500–3999 g (comparator group), <1000 g (group 1), 1000–1499 g (group 2), 1500–2499 g (group 3), and >4000 g (group 4). The 0.5th and 99.5th percentiles were used as the cut-off values. Comparisons were done on amino acid and acylcarnitines concentrations between the groups. False positive rate, positive predictive value, corrected false positive rate by birth weights were determined.

Results

Data on a total of 578,287 newborn infants were included in the analysis. The total false positive rate was 0.75%, and positive predictive value 2.89%. The false positive rate was 0.69%, 0.54% and 5.31% in infants with normal birth weight, birth weight of >4000 (group 4) and low birth weight of < 2500 g (groups 1, 2 and 3), respectively. Low-birth weight infants had much higher phenylalanine, tyrosine, methionine, arginine, propionylcarnitine, isovalerylcarnitine and octadecanoylcarnitine concentrations. Free carnitines and palmitoylcarnitine concentrations were lower. After adjusting for birth weight, false positive rate of all indices decreased to 0.53%, and positive predictive value increased to 4.31%.

Conclusions

Amino acid and carnitine concentrations in low-birth weight newborn infants may differ from the normal term newborn infants. The cut-off values of individual metabolites should be adjusted based on birth weight, to reduce false positive rate and increase positive predictive value.

Expanding preconception carrier screening for the Jewish population using high throughput microfluidics technology and next generation sequencing

Background

Genetic screening to identify carriers of autosomal recessive diseases has become an integral part of routine prenatal care. In spite of the rapid growth of known mutations, most current screening programs include only a small subset of these mutations, and are performed using diverse molecular techniques, which are generally labor-intensive and time consuming. We examine the implementation of the combined high-throughput technologies of specific target amplification and next generation sequencing (NGS), for expanding the carrier screening program in the Israeli Jewish population as a test case.

Methods

We compiled a panel of 370 germline mutations, causing 120 disorders, previously identified in affected Jewish individuals from different ethnicities. This mutation panel was simultaneously captured in 48 samples using a multiplex PCR-based microfluidics approach followed by NGS, thereby performing 17,760 individual assays in a single experiment.

Results

The sensitivity (measured with depth of at least 50×) and specificity of the target capture was 98 and 95 % respectively, leaving minimal rate of inconclusive tests per sample tested. 97 % of the targeted mutations present in the samples were correctly identified and validated.

Conclusion

Our methodology was shown to successfully combine multiplexing of target specific primers, samples indexing and NGS technology for population genetic screens. Moreover, it’s relatively ease of use and flexibility of updating the targets screened, makes it highly suitable for clinical implementation. This protocol was demonstrated in pre-conceptional screening for pan-Jewish individuals, but can be applied to any other population or different sets of mutations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-016-0184-7) contains supplementary material, which is available to authorized users.

Expanded newborn screening of inborn errors of metabolism by capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS)

Expanded newborn screening of inborn errors of metabolism (IEM) based on tandem mass spectrometry technology has emerged as one of the most successful preventative healthcare initiatives for presymptomatic diagnosis and treatment of rare yet treatable genetic diseases. However, confirmatory testing using methods with improved specificity is required in clinical laboratories to improve the positive predictive value for certain classes of IEMs due to their high rates of false positives. Here, we describe recent advances for comprehensive profiling of amino acids and acylcarnitines derived from dried blood spot extracts or plasma using capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) that allows for resolution of major isobaric/isomeric interferences without complicated sample handling. The integration of online sample preconcentration together with desalting in CE-ESI-MS enables the direct analysis of hydrophilic amino acids, surface-active acylcarnitines, as well as labile thiols under a single format when using a simple aqueous buffer electrolyte system.

Screening newborns for candidate biomarkers of type 1 diabetes

Combining samples from a national neonatal screening programme with the information from a national health registry allow for unique opportunities in analysing newborn blood for protein changes that could predict eventual disease development. A nested case-control cohort (n = 54 cases, 108 controls) was analysed by proteomics as a new way of looking for biomarkers that could bolster prediction of T1D risk in newborns. Protein extraction and haemoglobin depletion were automated and samples were processed and analysed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). The data set was reduced to the highest quality peaks and analysed using conditional logistic regression. A total of 25 protein peaks were found to differ between the two groups. The automated haemoglobin depletion provides a platform for further proteomics studies of individual patient material. The method opens a door to a wealth of patient material stored as dried blood spots.

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.

Newborn Screening: Current Status

Newborn screening, which represents one of the major advances in child health of the past century, has been carried out in all fifty U.S. states since the 1970s. Newborn screening programs are state-run, and decisions are left to the individual states regarding the conditions to be screened for, the mechanism for confirmatory testing, follow-up care, and financing of the programs. Laboratory advances in tandem mass spectrometry make it possible to screen newborns for many rare inborn errors of metabolism. This raises many policy issues including screening's cost-effectiveness, ethics, quality, and oversight.

Expanded newborn screening of inherited metabolic disorders by tandem mass spectrometry: Clinical and laboratory aspects

Newborn screening started in the 1960s for the purpose of identifying phenylketonuric patients to begin early intervention and to prevent mental retardation in these patients. Soon thereafter, screening programs expanded to include additional genetic disorders added individually one at a time. In the 1980s, tandem mass spectrometry (MS/MS) was introduced in clinical laboratories, and in the 1990s, the technique was used for newborn screening. Unlike measuring one analyte at a time, MS/MS allows measurement of >40 analytes, in a few minutes with the use of a single assay. Currently, MS/MS is being used for the identification of several amino acid, organic acid and fatty acid disorders. Several states in the United States and many other countries are using MS/MS in newborn screening. However, there is a significant disparity among different newborn screening programs for disorders being screened by MS/MS and many other challenges are faced by the expanded newborn screening. It is anticipated that in the future the use of MS/MS in newborn screening will expand both at the analyte and geographic levels. Clinicians and laboratory scientists should become familiar with MS/MS, disorders being screened in their patients' population and the future of this emerging technology.

A biochemical perspective on the use of tandem mass spectrometry for newborn screening and clinical testing

The first newborn screen was a clinical test to detect a disorder of the biochemistry of the amino acid, phenylalanine. This disorder, known as phenylketonuria, produces profound mental retardation if not detected and treated early in life. Early screening programs relied on inexpensive population screening techniques that have all but been replaced by more accurate analytical methods such as tandem mass spectrometry (MS/MS). MS/MS enables a multianalyte approach for detecting biochemical disorders such that a metabolic profile is obtained rather than a single analyte measurement. The metabolic profile has clearly shown improvements in the detection of diseases such as phenylketonuria and several new disorders arising from errors in fatty acid oxidation and organic acid metabolism. MS/MS is a powerful tool for accessing the metabolic status of a newborn and can detect both inborn metabolic errors as well as examine the effect of acquired diseases or pharmacologic intervention on intermediary metabolism.

Use of tandem mass spectrometry for multianalyte screening of dried blood specimens from newborns

BACKGROUND

Over the past decade laboratories that test for metabolic disorders have introduced tandem mass spectrometry (MS/MS), which is more sensitive, specific, reliable, and comprehensive than traditional assays, into their newborn-screening programs. MS/MS is rapidly replacing these one-analysis, one-metabolite, one-disease classic screening techniques with a one-analysis, many-metabolites, many-diseases approach that also facilitates the ability to add new disorders to existing newborn-screening panels.

METHODS

During the past few years experts have authored many valuable articles describing various approaches to newborn metabolic screening by MS/MS. We attempted to document key developments in the introduction and validation of MS/MS screening for metabolic disorders. Our approach used the perspective of the metabolite and which diseases may be present from its detection rather than a more traditional approach of describing a disease and noting which metabolites are increased when it is present.

CONTENT

This review cites important historical developments in the introduction and validation of MS/MS screening for metabolic disorders. It also offers a basic technical understanding of MS/MS as it is applied to multianalyte metabolic screening and explains why MS/MS is well suited for analysis of amino acids and acylcarnitines in dried filter-paper blood specimens. It also describes amino acids and acylcarnitines as they are detected and measured by MS/MS and their significance to the identification of specific amino acid, fatty acid, and organic acid disorders.

CONCLUSIONS

Multianalyte technologies such as MS/MS are suitable for newborn screening and other mass screening programs because they improve the detection of many diseases in the current screening panel while enabling expansion to disorders that are now recognized as important and need to be identified in pediatric medicine.

The application of tandem mass spectrometry to neonatal screening for inherited disorders of intermediary metabolism

This review is intended to serve as a practical guide for geneticists to current applications of tandem mass spectrometry to newborn screening. By making dried-blood spot analysis more sensitive, specific, reliable, and inclusive, tandem mass spectrometry has improved the newborn detection of inborn errors of metabolism. Its innate ability to detect and quantify multiple analytes from one prepared blood specimen in a single analysis permits broad recognition of amino acid, fatty acid, and organic acid disorders. An increasing number of newborn screening programs are either utilizing or conducting pilot studies with tandem mass spectrometry. It is therefore imperative that the genetics community be familiar with tandem mass spectrometric newborn screening.