Neonatal Screening for Inherited Metabolic Diseases in 2016

Paving the way in implementation of SCID newborn screening in developing nations: feasibility study and strategies to move forward in Malaysia

Early diagnosis and effective management of Primary immunodeficiency diseases (PIDs), particularly severe combined immunodeficiency (SCID), play a crucial role in minimizing associated morbidities and mortality. Newborn screening (NBS) serves as a valuable tool in facilitating these efforts. Timely detection and diagnosis are essential for swiftly implementing isolation measures and ensuring prompt referral for definitive treatment, such as allogeneic hematopoietic stem cell transplantation. The utilization of comprehensive protocols and screening assays, including T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC), is essential in facilitating early diagnosis of SCID and other PIDs, but their successful application requires clinical expertise and proper implementation strategy. Unfortunately, a notable challenge arises from insufficient funding for the treatment of PIDs. To address these issues, a collaborative approach is imperative, involving advancements in technology, a well-functioning healthcare system, and active engagement from stakeholders. The integration of these elements is essential for overcoming the existing challenges in NBS for PIDs. By fostering synergy between technology providers, healthcare professionals, and governmental stakeholders, we can enhance the efficiency and effectiveness of early diagnosis and intervention, ultimately improving outcomes for individuals with PIDs.

The investigation of serum phenylalanine levels based on infant feeding method: a cross-sectional study of children less than two years old with phenylketonuria (PKU)

BACKGROUND

Clinical advice may suggest discontinuing breastfeeding after the diagnosis of phenylketonuria in infants as the only effective way to monitor the newborn's intake and accurate measurement of phenylalanine (Phe). This study aims to investigate the prevalence and duration of breastfeeding, as well as its effect on serum Phe levels in infants with phenylketonuria at Education and Therapy Medical Center, Be'sat Hospital, Iran.

METHODS

We conducted a cross-sectional study of 34 children under two years old diagnosed with phenylketonuria between September 2018 and December 2022. Infants were categorized as breastfed and non-breastfed (bottle-fed) based on their feeding method after diagnosis. Data on age at diagnosis, medical records, demographic information, and anthropometric indices were collected, and infants with incomplete data or mixed feeding (formula + breast milk) were excluded from the study.

RESULTS

Of 94 infants managed in our hospital, 34 had complete medical records. Among the all patients 13 (38%) continued to be breastfed combined with phenylalanine-free amino acid-based protein substitute, while 21 (62%) were did not receive breast milk. The mean duration of breastfeeding was 2.57 ± 0.59 (1-3) months. The mean age at diagnosis was 22.6 ± 18.4 days. Phenylalanine concentrations at diagnosis were mean 10, SD 5.44; range 4-24 mg/dL [0.22-1.33 μmol/L] in the breastfed group and mean 14.3, SD 10.2; range 5-37 mg/dL [0.27-2.05 μmol/L] in the non-breastfed group.Non-breastfed infants had lower serum Phe levels than breastfed infants: mean 3.76, SD 2.10; range 1-7 mg/dL [0.05-0.38 μmol/L] and mean 4.89, SD 3.68; range 2-19 mg/dL [0.11-1.05 μmol/L], respectively, although not statistically significant [(t (34) = 118.0, P = 0.51]. Also we found no significant associations in body measurements for weight, height, and head circumference at birth and final assessment.

CONCLUSIONS

In conclusion, during treatment, there were no statistically significant associations between breastfeeding and serum Phe levels with growth in children with phenylketonuria.

Postmortem Identification of Genetic Variations Associated with Sudden Unexpected Death in Young People

Sudden unexpected death in the young (SUDY) is a traumatic occurrence for their family; however, information on the genetic variations associated with the condition is currently lacking. It is important to carry out postmortem genetic analyses in cases of sudden death to provide information for relatives and to allow appropriate genetic counselling and clinical follow-up. This study aimed to investigate the genetic variations associated with the occurrence of SUDY in Japan, using next-generation sequencing (NGS). The study included 18 cases of SUDY (16 males, 2 females; age 15-47 years) who underwent autopsy, including NGS DNA sequencing for molecular analysis. A total of 168 genes were selected from the sequencing panel and filtered, resulting in the identification of 60 variants in cardiac disease-related genes. Many of the cases had several of these genetic variants and some cases had a cardiac phenotype. The identification of genetic variants using NGS provides important information regarding the pathogenicity of sudden death.

Inherited Metabolic Diseases from Past to Present: A Bibliometric Analysis (1968-2023)

Bibliometric studies on inherited metabolic diseases (IMDs) do not exist in the literature. Therefore, our research aims to conduct a bibliometric study to determine the current status, trending topics, and missing points of publications on IMDs. Between 1968 and 2023, we conducted a literature search with the keyword "inherited metabolic disease" in the SCOPUS database. We included research articles in medicine written in English and published in the final section. We created our data pool using VOSviewer, SciMAT, and Rstudio software programs for the bibliometric parameters of the articles that met the inclusion criteria. We performed a bibliometric analysis of the data with the R package "bibliometrix" and BibExcel programs. We included 2702 research articles published on IMDs. The top three countries that have written the most articles in this field are the USA (n = 501), the United Kingdom (n = 182), and China (n = 172). The most preferred keywords by the authors were: newborn screening (n = 54), mutation (n = 43), phenylketonuria (n = 42), children (n = 35), genetics (n = 34), and maple syrup urine disease (n = 32). Trending topics were osteoporosis, computed tomography, bone marrow transplantation in the early years of the study, chronic kidney disease, urea cycle disorders, next-generation sequencing, newborn screening, and familial hypercholesterolemia in the final years of the study. This study provides clinicians with a new perspective, showing that molecular and genetic studies of inherited metabolic diseases will play an essential role in diagnosis and treatment in the future.

Contribution of Genetic Test to Early Diagnosis of Methylenetetrahydrofolate Reductase (MTHFR) Deficiency: The Experience of a Reference Center in Southern Italy

BACKGROUND

the deficiency of 5,10-Methylenetetrahydrofolate reductase (MTHFR) constitutes a rare and severe metabolic disease and is included in most expanded newborn screening (NBS) programs worldwide. Patients with severe MTHFR deficiency develop neurological disorders and premature vascular disease. Timely diagnosis through NBS allows early treatment, resulting in improved outcomes.

METHODS

we report the diagnostic yield of genetic testing for MTHFR deficiency diagnosis, in a reference Centre of Southern Italy between 2017 and 2022. MTHFR deficiency was suspected in four newborns showing hypomethioninemia and hyperhomocysteinemia; otherwise, one patient born in pre-screening era showed clinical symptoms and laboratory signs that prompted to perform genetic testing for MTHFR deficiency.

RESULTS

molecular analysis of the MTHFR gene revealed a genotype compatible with MTHFR deficiency in two NBS-positive newborns and in the symptomatic patient. This allowed for promptly beginning the adequate metabolic therapy.

CONCLUSIONS

our results strongly support the need for genetic testing to quickly support the definitive diagnosis of MTHFR deficiency and start therapy. Furthermore, our study extends knowledge of the molecular epidemiology of MTHFR deficiency by identifying a novel mutation in the MTHFR gene.

Breastfeeding practices for infants with inherited metabolic disorders: A survey of registered dietitians in the United States and Canada

Background

Objective

Design

Results

Conclusions

Qualitative evaluation of the symptoms and quality of life impacts of long-chain fatty acid oxidation disorders

BACKGROUND

Long-chain fatty acid oxidation disorders (LC-FAOD) are a group of rare autosomal-recessive genetic disorders characterized by metabolic deficiencies in which the body is unable to convert long-chain fatty acids into energy. To date, however, there is limited understanding of the patient experience of LC-FAOD.

METHODS

The symptoms, observable signs, and quality of life (QoL) impacts associated with LC-FAOD were explored via a focus group (n = 8) and semi-structured interviews (n = 6) with patients and caregivers of patients with LC-FAOD, and interviews (n = 4) with expert clinicians. Data were analyzed via thematic analysis and summarized in a conceptual model.

RESULTS

Participants reported a wide range of signs and symptoms associated with LC-FAOD, broadly categorized as musculoskeletal, endocrine/nutritional/metabolic, neurological, gastrointestinal/digestive, sensory, cardiovascular, respiratory, urological, and constitutional. LC-FAOD were reported to have a significant impact on various aspects of patients' lives including physical functioning, participation in daily activities, emotional/psychological wellbeing, and social functioning. Lifestyle modifications (such as diet and exercise restrictions) were necessary because of the condition. Symptoms were typically episodic in presentation often arising or exacerbated during catabolic conditions such as prolonged exercise, fasting, physiological stress, and illness/infection. Symptoms were also commonly reported to lead to emergency room visits, hospitalization, and clinical complications.

CONCLUSION

LC-FAOD have a considerable impact on patients' lives. There is a high degree of concordance in the signs, symptoms, and impacts of LC-FAOD reported by patients, caregivers, and clinicians; however, there were many symptoms and impacts that were only reported by patients and caregivers, thus demonstrating that insights from patient/caregiver experience data are integral for informing medical product development and facilitating patient-centered care.

Newborn screening for inherited metabolic diseases using tandem mass spectrometry in China: Outcome and cost-utility analysis

OBJECTIVES

Few studies in China have focused on the economic evaluation of newborn screening (NBS) for inherited metabolic disorders (IMDs) by tandem mass spectrometry (MS/MS). This study assesses the total costs, benefits, benefit-cost ratio (BCR), cost-utility ratio (CUR) and incremental cost-utility ratio (ICUR) of NBS using MS/MS compared to the non-screened group.

METHODS

The NBS outcomes of newborns who underwent MS/MS screening for IMDs in 2009-2018 were retrospectively reviewed. Records were extracted from a screening management system at the NBS Center of Zhejiang province. A cost-benefit analysis of screening was conducted, assessing screening costs for each subject, and direct and indirect treatment costs for IMDs detected by screening. The putative benefit of clinical outcomes related to early diagnosis was assumed to be improvement in quality of life and prolonged life expectancy in the screened group, as compared to the non-screened group.

RESULTS

Of the 3,040,815 newborns screened, 735 (2.86%) cases were diagnosed through gene sequence analysis. The most frequently occurring types of IMD were amino acid disorders (n = 276), then fatty acid oxidation disorders (n = 248), followed by organic acidaemias (n = 211). The difference in quality-adjusted life-years (QALYs) ranged from 0.78 to 15.4 in the screened group. The CUR was CNY¥ 116,183.89/QALY in the screened group and CNY¥ 3,078,823.65/QALY in the non-screened group. The ICUR was CNY¥ -768,428.76/QALY, and the BCR was 6.09.

CONCLUSIONS

NBS using MS/MS can be considered cost-effective in China. The nationwide promotion of NBS using MS/MS deserves priority consideration and sufficient publicity.

Use of nuclear magnetic resonance spectroscopy in diagnosis of inborn errors of metabolism

Nuclear Magnetic Resonance (NMR) spectroscopy has been applied in many fields of science and is increasingly being considered as a tool in the clinical setting. This review examines its application for diagnosis of inborn errors of metabolism (IEMs). IEMs, whether involving deficiency in the synthesis and degradation of metabolites, or in lipoprotein metabolism, affect nearly 3% of the global population. NMR is a preferred method for comprehensive evaluation of complex biofluids such as blood or urine, as it can provide a relatively unbiased overview of all compounds that are present and does not destroy or otherwise chemically alter the sample. While current newborn screening programs take advantage of other more sensitive methods, such as mass spectrometry, NMR has advantages especially for urine analysis with respect to ease of sample preparation and the reproducibility of results. NMR spectroscopy is particularly compatible with analysis of lipoproteins because it provides information about their size and density, not easily attained by other methods, that can help the clinician to better manage patients with dyslipidemia. We believe that NMR holds great potential for expanding clinical diagnosis in the future, in the field of IEMs and beyond.

Implementation of second-tier tests in newborn screening for the detection of vitamin B12 related acquired and genetic disorders: results on 258,637 newborns

BACKGROUND

Alteration of vitamin B₁₂ metabolism can be genetic or acquired, and can result in anemia, failure to thrive, developmental regression and even irreversible neurologic damage. Therefore, early diagnosis and intervention is critical. Most of the neonatal cases with acquired vitamin B₁₂ deficiency have been detected by clinical symptoms and only few of them trough NBS programs. We aim to assess the usefulness of the second-tier test: methylmalonic acid (MMA), methylcitric acid (MCA) and homocysteine (Hcys) in our newborn screening program and explore the implications on the detection of cobalamin (vitamin B₁₂) related disorders, both genetic and acquired conditions.

METHODS

A screening strategy using the usual primary markers followed by the analysis of MMA, MCA and Hcys as second tier-test in the first dried blood spot (DBS) was developed and evaluated.

RESULTS

During the period 2015-2018 a total of 258,637 newborns were screened resulting in 130 newborns with acquired vitamin B₁₂ deficiency (incidence 1:1989), 19 with genetic disorders (incidence 1:13,613) and 13 were false positive. No false negatives were notified. Concerning the second-tier test, the percentage of cases with MMA above the cut-off levels, both for genetic and acquired conditions was very similar (58% and 60%, respectively). Interestingly, the percentage of cases with increased levels of Hcys was higher in acquired conditions than in genetic disorders (87% and 47%, respectively). In contrast, MCA was high only in 5% of the acquired conditions versus in 53% of the genetic disorders, and it was always very high in all patients with propionic acidemia.

CONCLUSIONS

When screening for methylmalonic acidemia and homocystinuria, differential diagnosis with acquired vitamin B₁₂ deficiency should be done. The results of our strategy support the inclusion of this acquired condition in the NBS programs, as it is easily detectable and allows the adoption of corrective measures to avoid the consequences of its deficiency.

Sudden Infant Death Syndrome: Beyond Risk Factors

Sudden infant death syndrome (SIDS) is defined as "the sudden death of an infant under 1 year of age which remains unexplained after thorough investigation including a complete autopsy, death scene investigation, and detailed clinical and pathological review". A significant decrease of SIDS deaths occurred in the last decades in most countries after the beginning of national campaigns, mainly as a consequence of the implementation of risk reduction action mostly concentrating on the improvement of sleep conditions. Nevertheless, infant mortality from SIDS still remains unacceptably high. There is an urgent need to get insight into previously unexplored aspects of the brain system with a special focus on high-risk groups. SIDS pathogenesis is associated with a multifactorial condition that comprehends genetic, environmental and sociocultural factors. Effective prevention of SIDS requires multiple interventions from different fields. Developing brain susceptibility, intrinsic vulnerability and early identification of infants with high risk of SIDS represents a challenge. Progress in SIDS research appears to be fundamental to the ultimate aim of eradicating SIDS deaths. A complex model that combines different risk factor data from biomarkers and omic analysis may represent a tool to identify a SIDS risk profile in newborn settings. If high risk is detected, the infant may be referred for further investigations and follow ups. This review aims to illustrate the most recent discoveries from different fields, analyzing the neuroanatomical, genetic, metabolic, proteomic, environmental and sociocultural aspects related to SIDS.

Univariate Analysis of Short-Chain Fatty Acids Related to Sudden Infant Death Syndrome

Sudden infant death syndrome (SIDS) is defined as the death of a child under one year of age, during sleep, without apparent cause, after exhaustive investigation, so it is a diagnosis of exclusion. SIDS is the principal cause of death in industrialized countries. Inborn errors of metabolism (IEM) have been related to SIDS. These errors are a group of conditions characterized by the accumulation of toxic substances usually produced by an enzyme defect and there are thousands of them and included are the disorders of the β-oxidation cycle, similarly to what can affect the metabolism of different types of fatty acid chain (within these, short chain fatty acids (SCFAs)). In this work, an analysis of postmortem SCFAs profiles of children who died due to SIDS is proposed. Initially, a set of features containing SCFAs information, obtained from the NIH Common Fund's National Metabolomics Data Repository (NMDR) is submitted to an univariate analysis, developing a model based on the relationship between each feature and the binary output (death due to SIDS or not), obtaining 11 univariate models. Then, each model is validated, calculating their receiver operating characteristic curve (ROC curve) and area under the ROC curve (AUC) value. For those features whose models presented an AUC value higher than 0.650, a new multivariate model is constructed, in order to validate its behavior in comparison to the univariate models. In addition, a comparison between this multivariate model and a model developed based on the whole set of features is finally performed. From the results, it can be observed that each SCFA which comprises of the SFCAs profile, has a relationship with SIDS and could help in risk identification.

Conjugating immunoassays to mass spectrometry: Solutions to contemporary challenges in clinical diagnostics

Developments in immunoassays and mass spectrometry have independently influenced diagnostic technology. However, both techniques possess unique strengths and limitations, which define their ability to meet evolving requirements for faster, more affordable and more accurate clinical tests. In response, hybrid techniques, which combine the accessibility and ease-of-use of immunoassays with the sensitivity, high throughput and multiplexing capabilities of mass spectrometry are continually being explored. Developments in antibody conjugation methodology have expanded the role of these biomolecules to applications outside of conventional colorimetric assays and histology. Furthermore, the range of different mass spectrometry ionisation and analysis technologies has enabled its successful adaptation as a detection method for numerous clinically relevant immunological assays. Several recent examples of combined mass spectrometry-immunoassay techniques demonstrate the potential of these methods as improved diagnostic tests for several important human diseases. The present challenges are to continue technological advancements in mass spectrometry instrumentation and develop improved bioconjugation methods, which can overcome their existing limitations and demonstrate the clinical significance of these hybrid approaches.

Inborn errors of metabolism detectable by tandem mass spectrometry in Beijing

Background Individual inborn errors of metabolism (IEMs) are rare disorders. Expanded newborn screening for IEMs by tandem mass spectrometry (TMS) is an efficient approach for early diagnosis. Here we provide the newborn screening program for the application of this approach (between July 2014 and March 2019) to the identification of newborns in Beijing at risk of developing a potentially fatal disease. Methods The amino acids and acylcarnitines in dried blood spots were analyzed by TMS. Diagnoses of newborns with elevated metabolites were confirmed by gas chromatography-mass spectrometry, biochemical studies, and genetic analysis. Results Among the healthy newborns, 16 metabolic disorder cases were confirmed, giving a total birth prevalence of 1:3666 live births. Organic acidemia (OA) was the most common (9/16 patients; 56%), and methylmalonic acidemia was the most frequently observed OA (7/9 patients; 89%). Five infants were diagnosed with methylmalonic acidemia with homocystinuria type CblC, two with isolated methylmalonic acidemia, one with propionic acidemia, and one with isovaleric acidemia. Four patients (4/16, 25%) were diagnosed with hyperphenylalaninemia. One suffered with medium-chain acyl CoA dehydrogenase deficiency, one with carnitine uptake deficiency, and one with citrin deficiency. Eleven cases underwent genetic analysis. Seventeen mutations in eight IEM-associated genes were identified in 11 confirmed cases. Symptoms were already present within 2 days after birth in 44% (7/16) cases. The infant with propionic acidemia died at 7 days after birth. The other cases received timely diagnosis and treatment, and most of them grew well. Conclusions The results illustrate challenges encountered in disease management highlighting the importance of newborn screening for inherited metabolic disorders, which is not yet nationally available in our country. Regional newborn screening programs will provide a better estimation of the incidence of IEM.

A Strategy Employing a TF-Splinting Duplex Nanoswitch to Achieve Single-Step, Enzyme-Free, Signal-On Detection of l-Tryptophan

Transcription factor (TF)-based metabolite detection mainly depends on TF-regulated gene expression in cells. From TF activation to gene transcription and translation, the signal travels a relatively long way before it is received. Here, we propose a TF-splinting duplex DNA nanoswitch to detect metabolites. We show its feasibility using tryptophan repressor (TrpR) to detect l-tryptophan as a model. The assay has been optimized and characterized after obtaining a proof of concept, and the detection of l-tryptophan in complex biological samples is feasible. Unlike an equivalent gene expression approach, the whole process is a single-step, enzyme-free, and signal-on method. It can be completed within 20 min. This proposed TF-splinting duplex has the potential to be applied to the quick and convenient detection of other metabolites or even TFs.

Metabolomics to Improve the Diagnostic Efficiency of Inborn Errors of Metabolism

Early diagnosis of inborn errors of metabolism (IEM)—a large group of congenital disorders—is critical, given that many respond well to targeted therapy. Newborn screening programs successfully capture a proportion of patients enabling early recognition and prompt initiation of therapy. For others, the heterogeneity in clinical presentation often confuses diagnosis with more common conditions. In the absence of family history and following clinical suspicion, the laboratory diagnosis typically begins with broad screening tests to circumscribe specialised metabolite and/or enzyme assays to identify the specific IEM. Confirmation of the biochemical diagnosis is usually achieved by identifying pathogenic genetic variants that will also enable cascade testing for family members. Unsurprisingly, this diagnostic trajectory is too often a protracted and lengthy process resulting in delays in diagnosis and, importantly, therapeutic intervention for these rare conditions is also postponed. Implementation of mass spectrometry technologies coupled with the expanding field of metabolomics is changing the landscape of diagnosing IEM as numerous metabolites, as well as enzymes, can now be measured collectively on a single mass spectrometry-based platform. As the biochemical consequences of impaired metabolism continue to be elucidated, the measurement of secondary metabolites common across groups of IEM will facilitate algorithms to further increase the efficiency of diagnosis.

Statistically Driven Metabolite and Lipid Profiling of Patients from the Undiagnosed Diseases Network

Advancements in molecular separations coupled with mass spectrometry have enabled metabolome analyses for clinical cohorts. A population of interest for metabolome profiling is patients with rare disease for which abnormal metabolic signatures may yield clues into the genetic basis, as well as mechanistic drivers of the disease and possible treatment options. We undertook the metabolome profiling of a large cohort of patients with mysterious conditions characterized through the Undiagnosed Diseases Network (UDN). Due to the size and enrollment procedures, collection of the metabolomes for UDN patients took place over 2 years. We describe the study designed to adjust for measurements collected over a long time scale and how this enabled statistical analyses to summarize the metabolome of individual patients. We demonstrate the removal of time-based batch effects, overall statistical characteristics of the UDN population, and two case studies of interest that demonstrate the utility of metabolome profiling for rare diseases.

Increased parental anxiety and a benign clinical course: Infants identified with short-chain acyl-CoA dehydrogenase deficiency and isobutyryl-CoA dehydrogenase deficiency through newborn screening in Georgia

The long-term consequences and need for therapy in children with short-chain acyl-CoA dehydrogenase deficiency (SCADD) or isobutyryl-CoA dehydrogenase deficiency (IBDD) identified via newborn screening (NBS) remains controversial. Initial clinical descriptions were severe; however, while most cases identified through NBS have remained asymptomatic, clinical concerns have been raised in these populations. It is not clear whether these children are asymptomatic because of the success of NBS, or because the normal clinical course of these disorders is relatively benign. To evaluate these possibilities in our program, we evaluated the clinical outcomes of children with SCADD or IBDD identified by the Georgia NBS compared to the health status of a healthy age-matched control group. We also assessed parental anxiety during a phone interview both subjectively and objectively using the Pediatric Inventory for Parents (PIP), a validated measure of illness-related parental stress. The general health of 52 SCADD and nine IBDD cases from 2007 to 2016 were compared to the general health of unaffected control children obtained through the Centers for Disease Control and Prevention (CDC) parent listserv. We also collected statements from parents who participated in a phone survey regarding events they experienced during and after their diagnostic process. Overall, the children with SCADD and IBDD had no major health problems. There was no significant difference in cognitive development (p = .207). We identified a slightly higher incidence of reported neonatal hypoglycemia in the SCADD group; two of these occurred in the context of maternal diabetes. All interviewed parents reported extreme anxiety during the diagnostic period and current feelings of uncertainty about their child's future. PIP scores for all six caregivers who responded to that portion of the survey were consistent with some degree of parental stress. The greatest reported stressor was the unknown long-term impact of the illness. All children with SCADD and IBDD had no significant long-term sequelae. The phone interviews revealed substantial parental anxiety about the identification and follow-up of SCADD and IBDD. Based on our findings, the anxiety parents experience may be unwarranted given that we see no disease-associated morbidity or mortality in these children. Consideration should be given to the removal of these conditions from NBS panels, or if that is not possible, clinicians could educate parents on the benign nature of these diagnoses and release them from follow-up without treatment.

Hydrocephalus in cblC type methylmalonic acidemia

Methylmalonic acidemia (MMA) is a typical type of organic acidemia caused by defects in methylmalonyl-CoA mutase or adenosyl-cobalamin synthesis. Hydrocephalus (HC), results from an imbalance between production and absorption of cerebrospinal fluid (CSF), causeing enlarged cerebral ventricles and increased intracranial pressure, is a condition that requires urgent clinical decision-making. MMA without treatment could result in brain damage. However, HC in MMA was rarely reported. In this study, 147 MMA were identified from 9117 high risk children by gas chromatography mass spectrometry (GC/MS) for organic acidurias screening in urine samples and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for amino acids detection in blood samples. Totally 10 cases with MMA and HC were determined by brain MRI/CT, as well as gene mutation testing either by high throughput sequencing or Sanger sequencing. Besides, homocysteine was also analyzed for the 10 MMA with HC. Out of them, 9 cases carry out compound heterozygous mutations or homozygous mutation in MMACHC gene, and 1 case has MUTmutation. The mutation c.609G > A in MMACHC was the most common in the cbl type patients. Although MMA has a high incidence in Shandong province of China, especially cblC type. All of the 10 patients were not correctly diagnosed before developing HC. As a result, when a child develops progressive and refractory HC, the screening for inherited metabolic diseases should be immediately conducted.

Application of Next-Generation Sequencing Following Tandem Mass Spectrometry to Expand Newborn Screening for Inborn Errors of Metabolism: A Multicenter Study

This study explored the effectiveness of expanding newborn screening (NBS) by tandem mass spectrometry (TMS) and gene diagnosis by next-generation sequencing (NGS). First, we described the characteristics of gene variants in Jiangsu Province. We collected clinical data from three NBS centers. All infants followed a unified screening and diagnosis process. After obtaining informed consent, dried blood spots (DBSs) were collected and analyzed by TMS. If the results fell outside of the cut-off value, repeat analysis was performed. If the re-test results remained abnormal, the infant was recalled for further assessment. We performed targeted sequencing using the extended edition panel of inborn errors of metabolism (IEM) to detect 306 genes using the Illumina HiSeq 2500 platform. A total of 536,008 babies underwent NBS by TMS in three NBS centres. In total, 194 cases were eventually diagnosed with various types of inherited metabolic diseases, with an overall incidence of 1/2763. There were 23 types of diseases, including ten amino acid disorders (43.5%), eight organic acidaemias (34.8%) and five fatty acid oxidation defects (21.7%). In these infants, we clearly identified variants of disease-causing genes by next-generation sequencing (NGS). Most had two variants and others had one or three variants: 88% of gene variants were heterozygous and 12% were homozygous. There is a certain incidence of IEM in Jiangsu Province and it is necessary to carry out screening for 27 diseases. Meanwhile, NGS combined with TMS offers an enhanced plan for NBS for IEM.

Biochemical screening of intellectually disabled and healthy children in Punjab, Pakistan: differences in liver function test and lipid profiles

Objectives: Inborn errors of metabolism (IEMs) are rare genetic disorders. Generally, IEMs are untreatable; however, some IEMs causing intellectual disability are potentially treatable if diagnosed earlier. In this study, levels of some clinically important biochemical parameters in intellectually disabled children suspected for IEMs were tested to see their association with intellectual disability, which could be helpful in preliminary screening. Methods: This comparative cross-sectional observational study was carried out from 2014 to 2017. Blood samples from 800 boys and girls (aged 4-24 years) were collected, of which 391 were healthy (IQ >90) and 409 were intellectually disabled (IQ <70) children with unknown cause. Clinically important (Liver and kidney enzymes etc.) biochemical parameters were analyzed in sera samples using commercial kits on semi-automated clinical chemistry analyzer. Results: Serum analysis showed the levels of ALP (p < 0.00001), ASAT (p = 0.001), ALAT (p = 0.016), albumin (p < 0.001), uric acid (p < 0.001), cholesterol (p < 0.001), triglycerides (p < 0.001), and hemoglobin (p = 0.005) were significantly different between healthy and intellectually disabled children. Conclusion: Changes in the liver function test and lipid profile parameters were significantly different in children with intellectual disability; however, it requires further detailed analysis for complete characterization of these diseases.

Newborn screening for lysosomal storage disorders by tandem mass spectrometry in North East Italy

BACKGROUND

Lysosomal storage diseases (LSDs) are inborn errors of metabolism resulting from 50 different inherited disorders. The increasing availability of treatments and the importance of early intervention have stimulated newborn screening (NBS) to diagnose LSDs and permit early intervention to prevent irreversible impairment or severe disability. We present our experience screening newborns in North East Italy to identify neonates with Mucopolysaccharidosis type I (MPS I) and Pompe, Fabry, and Gaucher diseases.

METHODS

Activities of acid β-glucocerebrosidase (ABG; Gaucher), acid α-glucosidase (GAA; Pompe), acid α-galactosidase (GLA; Fabry), and acid α-L-iduronidase (IDUA; MPS-I) in dried blood spots (DBS) from all newborns during a 17-month period were determined by multiplexed tandem mass spectrometry (MS/MS) using the NeoLSD^® assay system. Enzymatic activity cutoff values were determined from 3500 anonymous newborn DBS. In the screening study, samples were retested if the value was below cutoff and a second spot was requested, with referral for confirmatory testing and medical evaluation if a low value was obtained.

RESULTS

From September 2015 to January 2017, 44,411 newborns were screened for the four LSDs. We recalled 40 neonates (0.09%) for collection of a second DBS. Low activity was confirmed in 20, who had confirmatory testing. Ten of 20 had pathogenic mutations: two Pompe, two Gaucher, five Fabry, and one MPS-I. The incidences of Pompe and Gaucher diseases were similar (1/22,205), with Fabry disease the most frequent (1/8882) and MPS-I the rarest (1/44411). The combined incidence of the four disorders was 1/4411 births.

CONCLUSIONS

Simultaneously determining multiple enzyme activities by MS/MS, with a focus on specific biochemical markers, successfully detected newborns with LSDs. The high incidence of these disorders supports this screening program.

Newborn Screening for Primary Immunodeficiency Diseases: History, Current and Future Practice

The primary objective of population-based newborn screening is the early identification of asymptomatic infants with a range of severe diseases, for which effective treatment is available and where early diagnosis and intervention prevent serious sequelae. Primary immunodeficiency diseases (PID) are a heterogeneous group of inborn errors of immunity. Severe combined immunodeficiency (SCID) is one form of PID which is uniformly fatal without early, definitive therapy, and outcomes are significantly improved if infants are diagnosed and treated within the first few months of life. Screening for SCID using T cell receptor excision circle (TREC) analysis has been introduced in many countries worldwide. The utility of additional screening with kappa recombining excision circles (KREC) has also been described, enabling identification of infants with severe forms of PID manifested by T and B cell lymphopenia. Here, we review the early origins of newborn screening and the evolution of screening methodologies. We discuss current strategies employed in newborn screening programs for PID, including TREC and TREC/KREC-based screening, and consider the potential future role of protein-based assays, targeted sequencing, and next generation sequencing (NGS) technologies, including whole genome sequencing (WGS).