Diagnosis and therapeutic monitoring of inborn errors of metabolism in 100,077 newborns from Jining city in China

Establishment of Age Specific Reference Interval for Aminoacids and Acylcarnitine in Dried Blood Spot by Tandem Mass Spectrometry

The Extended Screening for Inborn Errors of Metabolism is done for aminoacidopathies, fatty acid oxidation disorders and organic acid disorders. In a single dried blood spot, the tandem mass spectrometry is capable of measuring multiple analytes like amino acids, acylcarnitines, nucleosides, succinylacetone and lysophosphatidylcholines. This study was proposed to establish age specific reference internal for aminoacids and acylcartinitine in dried blood spot by tandem mass spectrometry. A total of 480 apparently healthy children were enrolled for the study and sub classified into four groups as follows: Group A: 0-1 month, Group B: 1 month-1 year, Group C: 1-5 year and Group D: 5-12 years each having 120 participants. Sample size were calculated as per CLSI approved guidelines. Tables 1 and 2 presents the age-specific percentile distribution of aminoacids and acylcarnitines established from healthy subjects as per rank-based method recommended by the IFCC and CLSI. Tables 3, 4 and 5 presents the cut-off values of primary and secondary marker/ratios for screening of aminoacidopathies, fatty acid oxidation disorders and organic acid disorders respectively. As a general principle, the interpretation of extended newborn screening results should be based on age specific cut-off established by the laboratory for primary analyte concentration and secondary analyte concentration/ ratios. This study was useful in establishing age specific cut-off values for various amino acids and acylcarnitines in South Indian population. [Table: see text] [Table: see text] [Table: see text] [Table: see text] [Table: see text].

Selective screening for inborn errors of metabolism using tandem mass spectrometry in West Kazakhstan children: study protocol

Data on the prevalence of most inborn errors of metabolism are still unavailable in Kazakhstan. The study aims to perform selective screening for hereditary metabolic diseases among patients aged from 1 day to 18 years in western Kazakhstan using the LC-MS/MS method, with establishing the reference values for the content of amino acids, acylcarnitines, and succinylacetone in blood samples of healthy children. Tasks: 1. To assess the burden of metabolic disorders detected by LC-MS/MS in western Kazakhstan by examination of children at clinical risk in pediatric clinics throughout the region; https://www.frontiersin.org/register?returnUrl=https://loop.frontiersin.org 2. To set the reference values of metabolites in the child population; 3. To analyze the age distribution, prevalence, and age of onset for each identified IEM, further comparing the obtained findings with those from previously published reports in other populations.

METHODS

To set the reference values of 51 metabolites in the child population, 750 healthy children will be included. The selective screening will be performed among 1,500 patients aged 1 day to 18 years with suspected hereditary metabolic disorders.

ANTICIPATED RESULTS

The results of selective screening will be interpreted by comparison with the reference values established. Diagnosis will be based on clinical signs, blood levels of amino acids, acylcarnitines, succinylacetone, and urine levels of organic acids and tests for gene mutations. An assessment of 37 inborn errors of metabolism frequencies in high-risk children will be performed. The research will further develop the national as selective as expanded newborn screening programs. The study was registered in clinicaltrials. gov (https://www.

CLINICALTRIALS

gov/study/NCT05910151) on 16 June 2023.

Gene therapy for organic acidemias: Lessons learned from methylmalonic and propionic acidemia

Organic acidemias (OA) are a group of rare autosomal recessive disorders of intermediary metabolism that result in a systemic elevation of organic acid. Despite optimal dietary and cofactor therapy, OA patients still suffer from potentially lethal metabolic instability and experience long-term multisystemic complications. Severely affected patients can benefit from elective liver transplantation, which restores hepatic enzymatic activity, improves metabolic stability, and provides the theoretical basis for the pursuit of gene therapy as a new treatment for patients. Because of the poor outcomes reported in those with OA, especially methylmalonic and propionic acidemia, multiple gene therapy approaches have been explored in relevant animal models. Here, we review the results of gene therapy experiments performed using MMA and PA mouse models to illustrate experimental paradigms that could be applicable for all forms of OA.

Assessment of reference intervals of acylcarnitines in newborns in Siberia

   Background. The incidence of diseases associated with impaired transport and oxidation of fatty acids is from 1:5,000 to 1:9,000 newborns. High morbidity, risk of death in the absence of timely correction, non-specificity of clinical manifestations define the importance of their timely laboratory diagnosis based on the determination of free carnitine and acylcarnitines in the blood. Reference values for free carnitine and acylcarnitines vary in different populations.   The aim. To determine the reference intervals of free carnitine and acylcarnitines in newborns of the Irkutsk region and to compare them with similar reference intervals in newborns in other countries.   Methods. The analysis of 229 samples of drу blood spots of healthy newborn children of the Irkutsk region aged from 0 to 7 days was carried out. Analysis of acylcarnitine concentrations was performed using high performance liquid chromatography with tandem mass spectrometry.   Results. 2.5 and 97.5 percentiles (µmol/l) were calculateed for 13 acylcarnitines: C0 – [8.78; 38.08]; C2 – [3.55; 19.09]; C3 – [0.33; 1.96]; C4 – [0.08; 0.51]; C5 – [0.06; 0.44]; C5DC – [0.03; 0.17]; C6 – [0.01; 0.07]; C8 – [0.01; 0.07]; C10 – [0.02; 0.07]; C12 – [0.04; 0.51]; C14 – [0.07; 0.24]; C16 – [0.58; 3.25]; C18 – [0.35; 1.16].   Conclusion. Differences in acylcarnitine reference intervals were found: compared with other countries, the concentrations of reference intervals for C0, C2, C3, C5DC, C8, C10, C14, C16 and C18 were lower in our study, reference intervals for C5 and C12 were higher in our country.

Epidemiology, methods of diagnosis, and clinical management of patients with arginase 1 deficiency (ARG1-D): A systematic review

BACKGROUND

Arginase 1 Deficiency (ARG1-D) is a rare, progressive, metabolic disorder that is characterized by devastating manifestations driven by elevated plasma arginine levels. It typically presents in early childhood with spasticity (predominately affecting the lower limbs), mobility impairment, seizures, developmental delay, and intellectual disability. This systematic review aims to identify and describe the published evidence outlining the epidemiology, diagnosis methods, measures of disease progression, clinical management, and outcomes for ARG1-D patients.

METHODS

A comprehensive literature search across multiple databases such as MEDLINE, Embase, and a review of clinical studies in ClinicalTrials.gov (with results reported) was carried out per PRISMA guidelines on 20 April 2020 with no date restriction. Pre-defined eligibility criteria were used to identify studies with data specific to patients with ARG1-D. Two independent reviewers screened records and extracted data from included studies. Quality was assessed using the modified Newcastle-Ottawa Scale for non-comparative studies.

RESULTS

Overall, 55 records reporting 40 completed studies and 3 ongoing studies were included. Ten studies reported the prevalence of ARG1-D in the general population, with a median of 1 in 1,000,000. Frequently reported diagnostic methods included genetic testing, plasma arginine levels, and red blood cell arginase activity. However, routine newborn screening is not universally available, and lack of disease awareness may prevent early diagnosis or lead to misdiagnosis, as the disease has overlapping symptomology with other diseases, such as cerebral palsy. Common manifestations reported at time of diagnosis and assessed for disease progression included spasticity (predominately affecting the lower limbs), mobility impairment, developmental delay, intellectual disability, and seizures. Severe dietary protein restriction, essential amino acid supplementation, and nitrogen scavenger administration were the most commonly reported treatments among patients with ARG1-D. Only a few studies reported meaningful clinical outcomes of these interventions on intellectual disability, motor function and adaptive behavior assessment, hospitalization, or death. The overall quality of included studies was assessed as good according to the Newcastle-Ottawa Scale.

CONCLUSIONS

Although ARG1-D is a rare disease, published evidence demonstrates a high burden of disease for patients. The current standard of care is ineffective at preventing disease progression. There remains a clear need for new treatment options as well as improved access to diagnostics and disease awareness to detect and initiate treatment before the onset of clinical manifestations to potentially enable more normal development, improve symptomatology, or prevent disease progression.

Cut-off values in newborn screening for inborn errors of metabolism in Saudi Arabia

BACKGROUND

Newborn screening identifies individuals affected by a specific disorder within an apparently healthy population prior to the appearance of symptoms so that appropriate interventions can be initiated in time to minimize the harmful effects. Data on population based cut-off values, disease ranges for true positive cases, false positive rates, true positive rates, cut-off verification and comparisons with international cut-off ranges have not been done for Saudi Arabia.

OBJECTIVE

Establish population-based cut-off values and analyte ratios for newborn screening assays and clinically validate the values.

DESIGN

Population-based screening.

SETTING

Tertiary care hospitals and laboratories.

METHODS

After method verification, initial cut-off values were established by analyzing 400-500 dry blood spot (DBS) samples which were further evaluated after one year. About 74 000 patient results were reviewed to establish cut-off ranges from DBS samples received from five different hospitals during 2013-2020. Analysis was performed by tandem mass spectrometry (TMS) and a genetic screening processor. Confirmation of initial positive newborn screening results for different analytes were carried out using gas chromatography-mass spectrometry, high performance liquid chromatography and TMS.

MAIN OUTCOME MEASURES

Cut-off values, ratios, positive predictive values, false positive rate, true positive rate and disease range.

SAMPLE SIZE

74 000 samples.

RESULTS

Population based cut-off values were calculated at different percentiles. These values were compared with 156 true positive samples and 80 proficiency samples. The false positive rate was less than 0.04 for all the analytes, except for valine, leucine, isovalerylcarnitine (C5), biotinidase (BTD), 17-hydroxyprogesterone and thyroid stimulating hormone. The highest false positive rate was 0.14 for BTD which was due to pre-analytical errors. The analytical positive predictive values were greater than 80% throughout the eight years.

CONCLUSION

We have established clinical disease ranges for most of the analytes tested in our lab and several ratios which gives excellent screening specificity and sensitivity for early detection. The samples were representative of the local populations.

LIMITATIONS

Need for wider, population-based studies.

CONFLICT OF INTEREST

None.

Two Japanese siblings with arginase-1 deficiency identified using a novel frameshift mutation of ARG1 (p.Lys41Thrfs∗2)

We described two Japanese siblings with arginase-1 (ARG1) deficiency. A 10-year-old girl (the proband and elder sister) was referred to our hospital complaining about her short stature. We diagnosed her with ARG1 deficiency, possibly with elevated levels of blood ammonia and plasma arginine. Her younger sister was found to have spastic paraparesis in her lower extremities and short stature at the age of 4 years. The younger sister also had high levels of plasma arginine, instead of normal levels of blood ammonia. Interestingly, they also prefer to avoid protein-rich foods such as meat, soybeans, cow milk, and dairy products. Genetic testing identified compound heterozygous mutations (c.121_122insCTT [p.Lys41Thrfs^∗2] and c.298G>A [p.Asp100Asn]) in the ARG1 gene. The ARG1 mutation of p.Lys41Thrfs^∗2 is a novel pathogenic mutation according to open databases and literature.

Inherited metabolic disorders in the neonatal intensive care unit: Red flags to look out for

BACKGROUND

We aimed to assess symptoms, laboratory findings, and radiological abnormalities in patients diagnosed with inherited metabolic disorders (IMDs) in the neonatal intensive care unit.

METHODS

A total of 6,150 newborns treated in a third-level neonatal intensive care unit between 2012 and 2020 in Turkey were screened, of which 195 consulted with a suspicion of metabolic disease based on their clinical, laboratory, or radiological findings were included in the present study.

RESULTS

The prevalence of IMDs in the patients was 1:94.6. Those consulted in the department of pediatric metabolism were divided into two groups, with the 65 diagnosed with IMDs assigned as Group I, and the 130 patients who were not diagnosed with IMDs as Group II. The most common IMDs were organic acidemias (29.23%) and urea cycle disorders (UCDs) (26.15%). The rates of consanguinity marriage (75.3% vs 37.6%, P < 0.001), siblings diagnosed with an IMD (27.6% vs 3.8%, P < 0.001), and sibling death (56.9% vs 14.6%, P < 0.001) were higher in Group I than in Group II. Hyperammonemia (61.5% vs 18.4%, P < 0.001) was the most common laboratory finding in Group I, and anemia (Group I 60.0% vs 43.0% P = 0.033), metabolic acidosis (53.8% vs 36.9%, P = 0.028) and respiratory alkalosis (16.9% vs 1.5%, P < 0.001) were all higher in Group I.

CONCLUSIONS

This retrospective study found that the results of clinical findings and basic laboratory tests could be strong indicators of IMDs, although extensive newborn screening tests and advanced biochemical and genetic tests should be carried out for the diagnosis of IMDs in newborns.

Inborn Errors of Metabolism Screening in Neonates: Current Perspective with Diagnosis and Therapy

Inborn errors of metabolism (IEMs) are rare hereditary or acquired disorders resulting from an enzymatic deformity in biochemical and metabolic pathways influencing proteins, fats, carbohydrate metabolism, or hampered some organelle function. Even though individual IEMs are uncommon, together, they represent a diverse class of genetic diseases, with new issues and disease mechanisms being portrayed consistently. IEM includes the extraordinary multifaceted nature of the fundamental pathophysiology, biochemical diagnosis, molecular level investigation, and complex therapeutic choices. However, due to the molecular, biochemical, and clinical heterogeneity of IEM, screening alone will not detect and diagnose all illnesses included in newborn screening programs. Early diagnosis prevents the emergence of severe clinical symptoms in the majority of IEM cases, lowering morbidity and death. The appearance of IEM disease can vary from neonates to adult people, with the more serious conditions showing up in juvenile stages along with significant morbidity as well as mortality. Advances in understanding the physiological, biochemical, and molecular etiologies of numerous IEMs by means of modalities, for instance, the latest molecular-genetic technologies, genome engineering knowledge, entire exome sequencing, and metabolomics, have prompted remarkable advancement in detection and treatment in modern times. In this review, we analyze the biochemical basis of IEMs, clinical manifestations, the present status of screening, ongoing advances, and efficiency of diagnosis in treatment for IEMs, along with prospects for further exploration as well as innovation.

Identification of the metabolic signatures of prostate cancer by mass spectrometry-based plasma and urine metabolomics analysis

OBJECTIVE

Prostate cancer (PCa) is one of the most commonly diagnosed cancers among men which is associated with profound metabolic changes. Systematic analysis of the metabolic alterations and identification of new biomarkers may benefit PCa diagnosis and a deep understanding of the pathological mechanism. The purpose of this study was to determine the metabolic features of PCa.

METHODS

Plasma and urine metabolites from 89 prostate cancer (PCa) patients, 84 benign prostatic hyperplasia (BPH) patients, and 70 healthy males were analyzed using LC-MS/MS and GC-MS. The Orthogonalised Partial Least Squares Discriminant Analysis (OPLS-DA) was used to find the significantly changed metabolites. The clinical value of the candidate markers was examined by receiver operating characteristic curve analysis and compared with prostate-specific antigen (PSA).

RESULTS

Multivariate statistical analyses found a series of altered metabolites, which related to the urea cycle, tricarboxylic acid cycle (TCA), fatty acid metabolism, and the glycine cleavage system. Plasma Glu/Gln showed the highest predictive value (AUC = 0.984) when differentiating PCa patients from healthy controls, with a higher sensitivity than PSA (96.6% vs. 94.4%). Both Glu/Gln and PSA displayed a low specificity when differentiating PCa patients from BPH patients (<53.2%), while the combination of Glu/Gln and PSA can further increase the diagnostic specificity to 66.9%.

CONCLUSIONS

The present study showed the metabolic features of PCa, provided strong evidence that the amide nitrogen and the energy metabolic pathways could be a valuable source of markers for PCa. Several candidate markers identified in this study were clinically valuable for further assessment.

Prevalence of methylmalonic acidemia among newborns and the clinical-suspected population: a meta-analyse

IMPORTANCE

Knowing the scale of rare inborn errors is important for screening and resource allocation. Evidence on the prevalence of methylmalonic acidemia (MMA) among newborns and the clinical-suspected population from large-scale screening programs needs to be systematically synthesized.

OBJECTIVE

To estimate the worldwide prevalence of MMA for newborns and the clinical-suspected population and explore the differences in different regions, periods, and diagnostic technologies.

DATA SOURCES

MEDLINE, Embase, CRD, Cochrane Library, Scopus, CINAHL, and PROSPERO. Study Selection: All studies reporting the epidemiology characteristics of MMA were selected.

DATA EXTRACTION AND SYNTHESIS

Characteristics of study, subjects, and epidemiology were extracted, random-effect models were used for meta-analyses.

MAIN OUTCOME AND MEASURE

Pooled prevalence of MMA.

RESULTS

This study included 111 studies. The pooled prevalence of MMA worldwide was 1.14 per 100,000 newborns (1516/190,229,777 newborns, 95% CI: 0.99-1.29) and 652.11 per 100,000 clinical-suspected patients (1360/4,805,665 clinical-suspected individuals, CI: 544.14-760.07). Asia and Africa got a higher pooled prevalence of MMA. The prevalence of MMA in newborns increased through the years, while that in the clinical-suspected population decreased. Collecting blood ≥ 72 h after birth had a higher pooled prevalence of MMA than collecting during 24 h-72 h after birth. The combining-use of MS/MS and GC/MS had a higher pooled prevalence than the single-use of MS/MS or GC/MS. Prevalence of cbl C, mut, cbl B, cbl A, isolated MMA, combined MMA and homocystinuria, vitamin B12-responsive MMA was synthesized.

CONCLUSIONS AND RELEVANCE

Prevalence of MMA among newborns was extremely low, but considerably high in the clinical-suspected population, indicating the need for more efficient newborn screening strategies and closer monitoring of the high-risk population for the early signs of MMA. Asia and Africa should attach importance to the high prevalence of MMA. Further diagnostic tests were recommended for the combining-use vs single-use of MS/MS and GC/MS and for collecting blood after 72 h vs during 24-72 h after birth.

Selective screening for inborn errors of metabolism by tandem mass spectrometry at Sohag University Hospital, Egypt

BACKGROUND

Inborn errors of metabolism (IEMs) comprise a group of inherited diseases that can have devastating consequences and cause irreversible damage to different body systems and even lead to death. Newborn screening helps in the presymptomatic diagnosis of many medical disorders including IEMs. Early diagnosis and management of IEMs helps reduce morbidity and mortality.

OBJECTIVE

This study aimed to estimate the prevalence of IEMs among at-risk children and contribute toward early diagnosis and management in order to minimize morbidity and mortality.

METHODS

This prospective study was conducted at the Pediatrics and Neonatology Department, Sohag University Hospital, Egypt. The study enrolled 308 participants suspected of having IEMs. Cases were included based on the presence of any of the following: unexplained convulsions, persistent metabolic acidosis, persistent hypoglycemia, disturbed consciousness, delayed milestones, or family history of previous sibling death with IEMs or sibling death with a history suggestive of IEMs. All participants in the study were subjected to metabolic screening by tandem mass spectrometry (MS/MS).

RESULTS

Out of 308 neonates, 93 (30.2%) were diagnosed with IEMs. The most common diagnosis was phenylketonuria, followed by glutaric aciduria type 1 and maple syrup urine disease (43%, 19.4%, and 14%, respectively). Five patients had Canavan disease, four had medium-chain acyl CoA dehydrogenase deficiency, three had congenital lactic acidosis, two had methylmalonic acidemia, and two had primary carnitine deficiency. Propionic acidemia, isovaleric acidemia, homocystinuria, short-chain acyl CoA dehydrogenase deficiency, B-ketothiolase deficiency, and ketone body utilization defect were diagnosed in one patient each. Most patients improved (73.1%) following proper specific management.

CONCLUSION

We recommend newborn screening for IEMs using MS/MS, which may help with the early diagnosis and management of this group of disorders.

Impact of newborn screening on the reported incidence and clinical outcomes associated with medium- and long-chain fatty acid oxidation disorders

Fatty acid oxidation disorders (FAODs) are potentially fatal inherited disorders for which management focuses on early disease detection and dietary intervention to reduce the impact of metabolic crises and associated spectrum of clinical symptoms. They can be divided functionally into long-chain (LC-FAODs) and medium-chain disorders (almost exclusively deficiency of medium-chain acyl-coenzyme A dehydrogenase). Newborn screening (NBS) allows prompt identification and management. FAOD detection rates have increased following the addition of FAODs to NBS programs in the United States and many developed countries. NBS-identified neonates with FAODs may remain asymptomatic with dietary management. Evidence from numerous studies suggests that NBS-identified patients have improved outcomes compared with clinically diagnosed patients, including reduced rates of symptomatic manifestations, neurodevelopmental impairment, and death. The limitations of NBS include the potential for false-negative and false-positive results, and the need for confirmatory testing. Although NBS alone does not predict the consequences of disease, outcomes, or management needs, subsequent genetic analyses may have predictive value. Genotyping can provide valuable information on the nature and frequency of pathogenic variants involved with FAODs and their association with specific phenotypes. Long-term follow-up to fully understand the clinical spectrum of NBS-identified patients and the effect of different management strategies is needed.

Newborn Screening for Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase and Mitochondrial Trifunctional Protein Deficiencies Using Acylcarnitines Measurement in Dried Blood Spots-A Systematic Review of Test Accuracy

Background: Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and mitochondrial trifunctional protein (MTP) deficiencies are rare autosomal recessive fatty acid β-oxidation disorders. Their clinical presentations are variable, and premature death is common. They are included in newborn blood spot screening programs in many countries around the world. The current process of screening, through the measurement of acylcarnitines (a metabolic by-product) in dried blood spots with tandem mass spectrometry, is subject to uncertainty regarding test accuracy. Methods: We conducted a systematic review of literature published up to 19th June 2018. We included studies that investigated newborn screening for LCHAD or MTP deficiencies by tandem mass spectrometry of acylcarnitines in dried blood spots. The reference standards were urine organic acids, blood acylcarnitine profiles, enzyme analysis in cultured fibroblasts or lymphocytes, mutation analysis, or at least 10-year follow-up. The outcomes of interest were sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Assessment of titles, abstracts, and full-text papers and quality appraisal were carried out independently by two reviewers. One reviewer extracted study data. This was checked by a second reviewer. Results: Ten studies provided data on test accuracy. LCHAD or MTP deficiencies were identified in 23 babies. No cases of LCHAD/MTP deficiencies were identified in four studies. PPV ranged from 0% (zero true positives and 28 false positives from 276,565 babies screened) to 100% (13 true positives and zero false positives from 2,037,824 babies screened). Sensitivity, specificity, and NPV could not be calculated as there was no systematic follow-up of babies who screened negative. Conclusions: Test accuracy estimates of screening for LCHAD and MTP deficiencies with tandem mass spectrometry measurement of acylcarnitines in dried blood were variable in terms of PPVs. Screening methods (including markers and thresholds) varied between studies, and sensitivity, specificity, and NPVs are unknown.

Compromised therapeutic value of pediatric liver transplantation in ethylmalonic encephalopathy: A case report

BACKGROUND

Ethylmalonic encephalopathy (EE) is a rare autosomal recessive metabolic disorder caused by impaired mitochondrial sulfur dioxygenase. Due to poor therapeutic effect of current conventional treatments, progressive psychomotor regression and neurological impairment usually contribute to early death in the first decade of life. Liver transplantation (LT) is emerging as a novel therapeutic option for EE; however, worldwide experience is still limited.

CASE SUMMARY

An 18-mo-old patient with the diagnosis of EE received a living donor liver transplant in our institution, which, to our knowledge, is the first case in Asian-Pacific countries. During 20 mo of follow-up, the longitudinal metabolic evaluations revealed a wild fluctuation in urinary EMA levels, still far beyond the normal range. Urinary 2-methylsuccinic acid levels gradually restored to normal, whereas the concentrations of urinary isobutyrylglycine and plasma C4- and C5-acylcarnitines fluctuated markedly and still remained above the reference limits. Only mild amelioration of petechiae and ecchymosis was observed, and no dramatic reversion of chronic mucoid diarrhea and orthostatic acrocyanosis occurred. Although brain magnetic resonance imaging suggested a certain improvement in basal ganglia lesions, the patient still presented developmental delay and neurologic disability.

CONCLUSION

LT may bring about a partial but not complete cure to EE. Given its definite role in defending against the devastating natural progression of EE, LT should still be considered for patients with EE in the absence of other superior therapeutic options. Early establishment of diagnosis and initiation of conventional treatment pre-transplant, timely LT, and continuous administration of metabolism-correcting medications post-transplant may be helpful in minimizing the neurologic impairment and maximizing the therapeutic value of LT in EE.

Ethnic preference distribution of inborn errors of metabolism: A 4-year study in a multi-ethnic region of China

Chinese newborns have been screened for inborn errors of metabolism (IEM) for over 20 years. Although China features 56 different ethnic groups, there are no specific data describing the incidence of such genetic errors across difference ethnicities. To understand the ethnic preference distribution of the incidence and variants of IEM in the Ningxia Hui Autonomous Region of China, 189,354 newborns from 2016 to 2019 were screened by tandem mass spectrometry, including 87,482 from the Han ethnic population, 88,229 from the Hui population, 1,103 from other ethnicities, and 12,540 infants without ethnic registration. Suspected cases then underwent specific genetic profiling by targeted next generation sequencing. In total, 160 patients were diagnosed with 17 types of IEM, with a significant higher incidence in Hui infants (1/1,003) than in Han infants (1/1,232). Five diseases (eight patients) were specifically detected in Han infants, while three were exclusively diagnosed in six Hui infants. For shared diseases, the variants of keys genes also showed ethnic preference. Our findings enhance our understanding of the genetics underlying IEM, thus promoting the development of treatment plans for patients from different areas or ethnicities in China.

A Great Catch for Investigating Inborn Errors of Metabolism-Insights Obtained from Zebrafish

Inborn errors of metabolism cause abnormal synthesis, recycling, or breakdown of amino acids, neurotransmitters, and other various metabolites. This aberrant homeostasis commonly causes the accumulation of toxic compounds or depletion of vital metabolites, which has detrimental consequences for the patients. Efficient and rapid intervention is often key to survival. Therefore, it requires useful animal models to understand the pathomechanisms and identify promising therapeutic drug targets. Zebrafish are an effective tool to investigate developmental mechanisms and understanding the pathophysiology of disorders. In the past decades, zebrafish have proven their efficiency for studying genetic disorders owing to the high degree of conservation between human and zebrafish genes. Subsequently, several rare inherited metabolic disorders have been successfully investigated in zebrafish revealing underlying mechanisms and identifying novel therapeutic targets, including methylmalonic acidemia, Gaucher’s disease, maple urine disorder, hyperammonemia, TRAPPC11-CDGs, and others. This review summarizes the recent impact zebrafish have made in the field of inborn errors of metabolism.

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.

Early access to biological neonatal screening: coordination among child care action programs

Objective:

To verify factors associated with early newborn access to biological neonatal screening.

Method:

A cross-sectional quantitative study was carried out with all newborns who underwent tests in healthcare units, hospitals, and laboratories of a city in the state of São Paulo, Brazil, with programs linking healthcare information. The following variables were investigated: child’s age at collection (dependent); place of collection; date of collection; and type of user (independent). Descriptive and inferential statistics were applied.

Results:

Records of 15,652 screenings were found in the two years analyzed. In the first year analyzed, 7,955 births and 7,640 (96.0%) tests were recorded, of which 5,586 (73.1%) were undertaken with newborns between three and five days old. In the next year analyzed, 8,316 births and 8,012 (96.3%) screenings were recorded, of which 7,025 (87.6%) were undertaken with newborns in the same age group. A statistically significant association was found between the variables “child’s age” and “type of user” in one year, and between the variables “child’s age” and “place of collection” in both years.

Conclusion:

Early access to these tests enables the screening of diseases and referral for treatment. The present study contributes to the management of child care programs by presenting strategies linking data and actions to improve access to biological neonatal screening.

Expanded newborn screening for inborn errors of metabolism by tandem mass spectrometry in newborns from Xinxiang city in China

Background

Tandem mass spectrometry is a powerful technology available in China over the last 15 years. The development of tandem mass spectrometry had made it possible to rapidly screen newborns for inborn errors of metabolism. The aim of this study was to determine the birth incidence of inborn errors of metabolism through expanded screening of newborns by tandem mass spectrometry in Xinxiang area.

Methods

Dried blood spots from 50 112 newborns were assessed for inborn errors of metabolism by tandem mass spectrometry. The diagnoses were confirmed based on the clinical features, conventional laboratory tests, and the organic acid levels tested in urine by gas chromatography‐mass spectrometry.

Results

The study findings revealed that 31 newborns were diagnosed with inborn errors of metabolism. The total incidence rate of inborn errors of metabolism was 1/1617, and these included 16 cases of amino acid disorders (51.6%), nine cases of organic acid disorders (29.0%), and 6 (19.4%) cases of fatty acid beta‐oxidation disorders.

Conclusions

The screening for the incidence of inborn errors of metabolism in Xinxiang area showed that the rate was higher than previously reported. This study provides valuable data which may be useful in facilitating improvements in the expansion of screening to enable early diagnosis and treatment of inborn errors of metabolism before the onset of symptoms.

Newborn screening and diagnosis of inborn errors of metabolism: A 5-year study in an eastern Chinese population

Inborn errors of metabolism (IEMs) can cause intellectual disability or even death in children. To evaluate the disease spectrum and genetic characteristics of IEMs in Jining City of Shandong Province in East China, we used tandem mass spectrometry (MS/MS) technology for IEMs screening combined with genetic analysis. Newborns were screened from July 14, 2014, to December 31, 2018. Amino acid and carnitine contents were detected by MS/MS. According to the results for normal newborns, the reference range of our laboratory was established with the percentile method. The suspected positive newborns were further diagnosed using next-generation sequencing. A total of 514,234 newborns were screened, and 265 were diagnosed with IEMs, with a detection rate of 1:1941. Of the 265 patients, 130 (49.06%) had organic acid disorders, 83 (31.32%) had amino acid disorders, 34 (12.83%) had fatty acid oxidation disorders, and 18 (6.79%) had urea circulatory disorders. PAHD and MMA were the two most common disorders. IEMs-associated genes were identified in 233 patients. Our data indicated that IEMs are never uncommon in Jining, and the disease spectrum and genetic background were clearly elucidated, contributing to the treatment and prenatal genetic counseling of these disorders in the region.

Clinical Spectrum of Inherited Disorders of Metabolism

OBJECTIVE

To study the clinical profile and outcome of children with Inborn errors of metabolism.

METHODS

Thirty one newly diagnosed children with Inborn errors of metabolism over a 1 y period were studied for their relevant clinical, biochemical, diagnosis, treatment and follow-up details.

RESULTS

Inborn errors of metabolism accounted for 2% of hospital admissions. Sixty five percent were born to parents of consanguineous marriage. Of the 31 children with Inborn errors of metabolism, 16 (51%) had lysosomal storage disorders, 8 (26%) had disorders of amino acid metabolism, 2 (6%) each had disorders of carbohydrate and bile acid metabolism, 1 (3%) each had disorders of fatty acid oxidation, mitochondrial and peroxisome metabolism. Acrodermatitis dysmetabolica, as a complication was observed in one child and the overall mortality rate in this series was 10%.

CONCLUSIONS

Lysosomal storage disorders constituted the majority of Inborn errors of metabolism in this series and amino acidopathies/organic acidemias were successfully treated with special formulas.

Biochemical Screening of Intellectually Disabled Patients: A Stepping Stone to Initiate a Newborn Screening Program in Pakistan

Inborn errors of metabolism (IEMs) are rare group of genetic disorders comprising of more than 1,000 different types. Around 200 of IEMs are potentially treatable through diet, pharmacological and other therapies, if diagnosed earlier in life. IEMs can be diagnosed early through newborn screening (NBS) programs, which are in place in most of the developed countries. However, establishing a NBS in a developing country is a challenging task due to scarcity of disease related data, large population size, poor economy, and burden of other common disorders. Since, not enough data is available for the prevalence of IEMs in Pakistan; therefore, in this study, we set out to find the prevalence of various treatable IEMs in a cohort of intellectually disabled patients suspected for IEMs, which will help us to initiate a NBS program for the most frequent IEMs in Pakistan. Therefore, a total of 429 intellectually disabled (IQ <70) patient samples were collected from Pakistan. A subset of 113 patient samples was selected based on the clinical information for the detailed biochemical screening. Advance analytical techniques like, Amino Acid Analyzer, GC-MS, UHPLC-MS, and MS/MS were used to screen for different treatable IEMs like aminoacidopathies, fatty acid β-oxidation disorders and mucopolysaccharidoses (MPS) etc. A total of 14 patients were diagnosed with an IEM i.e., 9 with homocystinuria, 2 with MPS, 2 with Guanidinoacetate methyltransferase (GAMT) deficiency and 1 with sitosterolemia. These IEMs are found frequent in the collected patient samples from Pakistan. Thus, present study can help to take an initiative step to start a NBS program in Pakistan, especially for the homocystinuria having highest incidence among aminoacidopathies in the studied patients, and which is amenable to treatment. This endeavor will pave the way for a healthier life of affected patients and will lessen the burden on their families and society.

Two Infants With Beta-Ketothiolase Deficiency Identified by Newborn Screening in China

Beta-ketothiolase deficiency (BKTD) is an autosomal recessive disease caused by a defect of mitochondrial acetoacetyl-CoA thiolase. Beginning in 2014, we carried out newborn screening by tandem mass spectrometry (MS/MS) followed by next-generation sequencing (NGS) and identified two infants with BKTD among 203,750 newborns born in Jiangsu Province, China. Both infants showed the characteristic chemical abnormalities of BKTD. We used NGS to confirm variants in the ACAT1. Patient 1 had the compound heterozygous variants c.721dupA and c.928G > C. Patient 2 had compound heterozygosity for the c.238+1G > A and c.1163G > T variants. c.721dupA, c.928G > C and c.1163G > T were suspected to be likely pathogenic, whereas c.238+1G > A was determined to be pathogenic. None of the four variants have been reported in the literature. Patient 1 presented with onset of metabolic acidosis and neonatal hypoglycemia 8 days after birth, whereas patient 2 was detected through neonatal disease screening but had no clinical manifestations. These findings contribute to our understanding of the clinical characteristics and genetic basis of BKTD.

A verification of the application of the non-derivatized mass spectrometry method in newborns screening of metabolic disorders

It is required that the clinical screening of metabolic disorders in newborns meet International Organization for Standardization 15189-2012 approval. The new tandem mass spectrometry (MS/MS) based screening system and its companion reagent should be independently authenticated before their implementation in clinical diagnosis laboratories.Linearity, stability, accuracy, and precision evaluations were carried out to verify the performance of the Waters ACQUITY TQD MS/MS system with the NeoBase non-derivatized MS/MS PerkinElmer kit for detecting amino acids and acylcarnitine in newborns with metabolic disorders.Statistically, the correlation coefficient (R) of 0.9982 to 0.9999 indicates good linearity. The measurements at the beginning and end of the reagent storage procedure were taken for stability verification. No significant difference was detected between the 2 periods. The amino acid exhibited a degree of bias in the range of 0% to 14.17%, with acylcarnitine's being was in the range of 0% to 14.84%; they consequently passed the quality assessment requirements for clinical laboratories of the China National Centre. The amino acids' within-run, between-run, and day-to-day run precision were 1.19% to 7.68%, 1.63% to 5.01%, and 4.77% to 12.48%, respectively, while the total imprecision was 5.55% to 13.33%. Acylcarnitine's within-run, between-run, and day-to-day run precision was 1.2% to 8.43%, 0.19% to 9.60%, and 2.33% to 10.74%, respectively, while it's total imprecision was 6.57% to 13.99%. The manufacturer declared that the total imprecision of the tests, using Multiple Reaction Monitoring, should be less than or equal to 25% of the coefficient of variation for the kit's high and low-quality control levels.The performance of the non-derivatized MS/MS screening system in detecting the amino acids and acylcarnitines passed the test's requirements. It was maintained in accordance with the routine clinical chemical detection system.

Knowledge about Neonatal Screening among Postpartum Women and Complexity Level of Birthing Facilities

BACKGROUND

To ascertain the degree of knowledge of postpartum women about important aspects related to the neonatal screening process and whether differences of opinion exist between those who deliver in low-complexity versus high-complexity health facilities (low-risk versus high-risk pregnancies, respectively).

METHODS

This was a prospective, cross-sectional, questionnaire-based study. The sample consisted of postpartum women recruited from 2013 to 2015 at public maternity hospitals in the city of Niterói, Brazil. Participants were divided into two groups and completed a questionnaire consisting of Likert-scored items. Continuous variables were analyzed with the Mann-Whitney test, and categorical variables, with Fisher's test. A confirmatory factor analysis of participants' answers was performed.

RESULTS

Of 188 women enrolled, 54 (28.7%) had incomplete elementary education; 119 (62.2%) had attended more than six antenatal care visits. The mean age was 25.57 years. Nearly all women (n = 179, 95.2%) were roomed-in with their infants. Knowledge of neonatal screening was very similar in the high-complexity and low-complexity groups. Divergences were limited to items regarding the risks of neonatal screening.

CONCLUSIONS

The degree of knowledge among postpartum women was similar among high- and low-complexity facilities. Those who attended high-complexity facilities had longer hospital stays and greater adherence to ethical issues regarding neonatal screening.

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.

Age-Specific Cut-off Values of Amino Acids and Acylcarnitines for Diagnosis of Inborn Errors of Metabolism Using Liquid Chromatography Tandem Mass Spectrometry

Liquid Chromatography tandem mass spectrometry (LC-MS/MS) is used for the diagnosis of more than 30 inborn errors of metabolisms (IEMs). Accurate and reliable diagnosis of IEMs by quantifying amino acids (AAs) and acylcarnitines (ACs) using LC-MS/MS systems depend on the establishment of age-specific cut-offs of the analytes. This study aimed to (1) determine the age-specific cut-off values of AAs and ACs in Bangladesh and (2) validate the LC-MS/MS method for diagnosis of the patients with IEMs. A total of 570 enrolled healthy participants were divided into 3 age groups, namely, (1) newborns (1-7 days), (2) 8 days–7 years, and (3) 8–17 years, to establish the age-specific cut-offs for AAs and ACs. Also, 273 suspected patients with IEMs were enrolled to evaluate the reliability of the established cut-off values. Quantitation of AAs and ACs was performed on an automated LC-MS/MS system using dried blood spot (DBS) cards. Then the specimens of the enrolled clinically suspected patients were analyzed by the established method. Nine patients came out as screening positive for different IEMs, including two borderline positive cases of medium-chain acyl-CoA dehydrogenase deficiency (MCAD). A second-tier test for confirmation of the screening positive cases was conducted by urinary metabolic profiling using gas chromatography- mass spectrometry (GC-MS). Out of 9 cases that came out as screening positive by LC-MS/MS, seven cases were confirmed by urinary GC-MS analysis including 3 cases with phenylketonuria, 1 with citrullinemia type II, 1 with methylmalonic acidemia, 1 with isovaleric acidemia and 1 with carnitine uptake defect. Two borderline positive cases with MCAD were found negative by urinary GC-MS analysis. In conclusion, along with establishment of a validated LC-MS/MS method for quantitation of AAs and ACs from the DBS cards, the study also demonstrates the presence of predominantly available IEMs in Bangladesh.

Newborn screening in the developing countries

PURPOSE OF REVIEW

We review newborn screening (NBS) publications from the developing countries to identify global progress in improving child health.

RECENT FINDINGS

Many developing countries do not yet have national NBS. As infant mortality rates decline, NBS gains in public health priority. Local incidence and outcome data are used to persuade health officials to include screening in priority health spending. Congenital hypothyroidism is the most cost-effective screened condition in most countries. In sub-Saharan Africa, India and some parts of Asia, screening for hemoglobinopathies and glucose-6-dehydrogenase deficiency are also important. Expanded screening for metabolic conditions is most needed in areas of high consanguinity. Screening for hearing disorders and critical congenital heart defects is increasing globally. The largest birth cohorts are India and China, but only China has successful NBS. Reports from completed government research projects in India support initiation of NBS.

SUMMARY

Government activities around NBS are increasing in India and there is increased emphasis on pilot programs for sickle cell NBS in sub-Saharan Africa. Genetic counseling training in Asia and Africa is increasing and will be helpful as part of NBS. To build successful screening programs, partnerships among health professionals, parents, policy makers and industry stakeholders are essential.