Screening for newborn fatty acid oxidation disorders in Chongqing and the follow-up of confirmed children.

OBJECTIVE: To investigate the incidence, clinical characteristics, gene mutations and prognosis of fatty acid oxidation disorders (FAOD) in newborns in Chongqing. METHODS: Blood samples were collected from 35 374 newborns for screening of FAOD in the Neonatal Screening Center of Women and Children's Hospital of Chongqing Medical University from July 2020 to February 2022. The acylcarnitine spectrum was detected by tandem mass spectrometry, the positive children in primary screening were recalled within 2 weeks, and the diagnosis of FAOD was confirmed by urine organic acid measurement, blood biochemistry testing and genetic analysis. The confirmed children were given early intervention, treatment and followed-up. RESULTS: Among 35 374 newborns, there were 267 positive children in primary screening, with a positive rate of 0.75%. Five children with FAOD were diagnosed by gene detection, with an incidence rate of 1/7075. Among them, there were 3 cases of primary carnitine deficiency (PCD, 1/11 791), 1 case of short-chain acyl-CoA dehydrogenase deficiency (SCADD, 1/35 374) and 1 case of very long-chain acyl-CoA dehydrogenase deficiency (VLCADD, 1/35 374). The c.1400C>G and c.338G>A were the common mutations of SLC22A5 gene in 3 children with PCD, while c.621G>T was a novel mutation. There were no clinical manifestations during the follow-up period in 2 children with supplementation of L-carnitine. Another child with PCD did not follow the doctor's advice of L-carnitine treatment, and had acute attack at the age of 6 months. The child recovered after treatment, and developed normally during the follow-up. The detected ACADS gene mutations were c.417G>C and c.1054G>A in child with SCADD, who showed normal intelligence and physical development without any clinical symptoms. The mutations of ACADVL gene were c.1349G>A and c.1843C>T in child with VLCADD, who showed acute attack in the neonatal period and recovered after treatment; the child was fed with milk powder rich in medium-chain fatty acids and had normal development during the follow-up. CONCLUSIONS: The incidence of FAOD in Chongqing area is relatively high. PCD is the most common type, and the clinical phenotype of VLCADD is serious. After early diagnosis through neonatal screening, standardized treatment and management is followed, most of FAOD children can have good prognosis.

Newborn screening and genetic variation of medium chain acyl-CoA dehydrogenase deficiency in the Chinese population.

OBJECTIVES: Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive disorder of the fatty acid oxidative metabolism. This study aimed to investigate the epidemiological characteristics, the spectrum of variation, clinical phenotype, and prognosis of MCADD in Chinese newborns. METHODS: We retrospectively analysed newborn screening (NBS) data in the Zibo area from January 2016 to March 2022 and summarized 42 cases recently reported in Chinese neonates. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and next-generation sequencing (NGS) were used to detect the concentrations of carnitine in the blood spots and for diagnosis. RESULTS: A total of 183,082 newborns were detected, and six patients were diagnosed with MCADD (1/3,0514). The primary octanoylcarnitine (C8) and the octanoylcarnitine/decanoylcarnitine ratio (C8/C10) were elevated in all patients. Gene analysis revealed four known and four novel variants of the ACADM gene. Five patients were asymptomatic and developed normally under dietary guidance. One child died of vaccination-induced MCADD, presenting with hypoglycemia and elevated acylcarnitines. CONCLUSIONS: The incidence of MCADD in Chinese newborns varies geographically from 1/222,903 to 1/30,514, and the most common pathogenic variant is c.449_452 del CTGA (p. T150Rfs∗4) in ACADM gene with a frequency of 27.7%. HPLC-MS/MS and genetic analysis are beneficial for early prevention and good prognosis of MCADD.

The frequencies of very long-chain acyl-CoA dehydrogenase deficiency genetic variants in Japan have changed since the implementation of expanded newborn screening.

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency has been a target of expanded newborn screening (ENBS) using tandem mass spectrometry in Japan. Since the implementation of ENBS, a number of novel ACADVL variants responsible for VLCAD deficiency have been identified. In this study, genotypic differences in Japanese patients with VLCAD deficiency were investigated before and after ENBS. The ACADVL variants in 61 subjects identified through ENBS (ENBS group) and in 40 patients who subsequently developed clinical symptoms without undergoing ENBS (pre-ENBS group) were compared. Subjects in the ENBS group underwent genetic testing and/or VLCAD enzyme activity measurements. Patients in the pre-ENBS group were stratified into three clinical phenotypes and underwent genetic testing. This study revealed that the variants p.K264E, p.K382Q and c.996dupT were found in both groups, but their frequencies were lower in the ENBS group (5.2%, 3.1% and 4.2%, respectively) than in the pre-ENBS group (16.5%, 12.7% and 10.1%, respectively). In addition, p.C607S, p.T409M, p.M478I, p.G289R, p.C237R, p.T260M, and p.R229* were exclusively identified in the ENBS group. Among these variants, p.C607S exhibited the highest frequency (18.8%). The patients who were heterozygous for p.C607S demonstrated 7-42% of control enzyme activity. p.C607S is suspected to be unique to Japanese individuals. According to a comparison of enzyme activity, patients with the p.C607S variant may exhibit higher enzyme activity than those with the p.A416T, p.A180T, p.R450H, and p.K264E variants, which are responsible for the myopathic form of the disease. The VLCAD deficiency genotypes have changed since the initiation of ENBS in Japan.

Target Diseases for Neonatal Screening in Germany.

BACKGROUND: Neonatal screening in Germany currently comprises 19 congenital diseases, 13 of which are metabolic diseases. Approximately one in 1300 newborns suffers from one of these target diseases. Early diagnosis and treatment enable the affected children to undergo better development and even, in many cases, to have a normal life. METHODS: This review is based on pertinent publications retrieved by a selective search in the PubMed and Embase databases. RESULTS: Positive screening findings are confirmed in approximately one out of five newborns. The prompt evaluation of suspected diagnoses is essential, as treatment for some of these diseases must be initiated immediately after birth to prevent longterm sequelae. The most commonly identified diseases are primary hypothyroidism (1:3338), phenylketonuria/hyperphenylalaninemia (1 : 5262), cystic fibrosis (1 : 5400), and medium-chain acyl-CoA dehydrogenase deficiency (1 : 10 086). Patient numbers are rising as new variants of the target diseases are being identified, and treatments must be adapted to their heterogeneous manifestations. Precise diagnosis and the planning of treatment, which is generally lifelong, are best carried out in a specialized center. CONCLUSION: Improved diagnosis and treatment now prolong the lives of many patients with congenital diseases. The provision of appropriate long-term treatment extending into adulthood will be a central structural task for screening medicine in the future.

Long-term Benefits and Harms Associated With Genetic Cholesteryl Ester Transfer Protein Deficiency in the General Population.

Importance: The balance between the potential long-term clinical benefits and harms associated with genetic cholesteryl ester transfer protein (CETP) deficiency, mimicking pharmacologic CETP inhibition, is unknown. Objective: To assess the relative benefits and harms associated with genetic CETP deficiency. Design, Setting, and Participants: This study examined 2 similar prospective cohorts of the Danish general population, with data on a total of 102 607 participants collected from October 10, 1991, through December 7, 2018. Exposures: Weighted CETP allele scores. Main Outcomes and Measures: Incident cardiovascular mortality, ischemic heart disease, myocardial infarction, ischemic stroke, peripheral arterial disease, vascular dementia, Alzheimer disease, all-cause mortality, and age-related macular degeneration (AMD). The study first tested whether a CETP allele score was associated with morbidity and mortality, when scaled to genetically lower levels of non-high-density lipoprotein (HDL) cholesterol (ie, 17 mg/dL), corresponding to the reduction observed for anacetrapib vs placebo in the Randomized Evaluation of the Effects of Anacetrapib Through Lipid-Modification (REVEAL) trial. Second, the study assessed how much of the change in morbidity and mortality was associated with genetically lower levels of non-HDL cholesterol. Finally, the balance between the potential long-term clinical benefits and harms associated with genetic CETP deficiency was quantified. For AMD, the analyses also included higher levels of HDL cholesterol associated with genetic CETP deficiency. Results: Of 102 607 individuals in the study, 56 559 (55%) were women (median age, 58 years [IQR, 47-67 years]). Multivariable adjusted hazard ratios showed that a genetically lower level of non-HDL cholesterol (ie, 17 mg/dL) was associated with a lower risk of cardiovascular mortality (hazard ratio [HR], 0.77 [95% CI, 0.62-0.95]), ischemic heart disease (HR, 0.80 [95% CI, 0.68-0.95]), myocardial infarction (HR, 0.72 [95% CI, 0.55-0.93]), peripheral arterial disease (HR, 0.80 [95% CI, 0.63-1.02]), and vascular dementia (HR, 0.38 [95% CI, 0.18-0.80]) and an increased risk of AMD (HR, 2.33 [95% CI, 1.63-3.30]) but was not associated with all-cause mortality (HR, 0.91 [95% CI, 0.81-1.02]), ischemic stroke (HR, 1.05 [95% CI, 0.81-1.36]), or Alzheimer disease (HR, 1.25 [95% CI, 0.89-1.76]). When scaled to a higher level of HDL cholesterol, the increased risk of AMD was even larger. A considerable fraction of the lower risk of cardiovascular end points was associated with genetically lower levels of non-HDL cholesterol, while the higher risk of AMD was associated with genetically higher levels of HDL cholesterol. Per 1 million person-years, the projected 1916 more AMD events associated with genetically higher levels of HDL cholesterol was similar to the 1962 fewer events of cardiovascular mortality and myocardial infarction combined associated with genetically lower levels of non-HDL cholesterol. Conclusions and Relevance: This study suggests that genetic CETP deficiency, mimicking pharmacologic CETP inhibition, was associated with a lower risk of cardiovascular morbidity and mortality, but with a markedly higher risk of AMD.

Impact of Newborn Screening and Early Dietary Management on Clinical Outcome of Patients with Long Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency and Medium Chain Acyl-CoA Dehydrogenase Deficiency-A Retrospective Nationwide Study.

Long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD/MTPD) and medium chain acyl-CoA dehydrogenase deficiency (MCADD) were included in the expanded neonatal screening program (ENBS) in Czechia in 2009, allowing for the presymptomatic diagnosis and nutritional management of these patients. The aim of our study was to assess the nationwide impact of ENBS on clinical outcome. This retrospective study analysed acute events and chronic complications and their severity in pre-ENBS and post-ENBS cohorts. In total, 28 children (12 before, 16 after ENBS) were diagnosed with LCHADD/MTPD (incidence 0.8/100,000 before and 1.2/100,000 after ENBS). In the subgroup detected by ENBS, a significantly longer interval from birth to first acute encephalopathy was observed. In addition, improvement in neuropathy and cardiomyopathy (although statistically non-significant) was demonstrated in the post-ENBS subgroup. In the MCADD cohort, we included 69 patients (15 before, 54 after ENBS). The estimated incidence rose from 0.7/100,000 before to 4.3/100,000 after ENBS. We confirmed a significant decrease in the number of episodes of acute encephalopathy and lower proportion of intellectual disability after ENBS (p < 0.0001). The genotype-phenotype correlations suggest a new association between homozygosity for the c.1528C > G variant and more severe heart involvement in LCHADD patients.

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 Program in the Community of Madrid: evaluation of positive cases.] / Análisis de casos positivos de cribado neonatal de errores congénitos del metabolismo en la Comunidad de Madrid.

OBJECTIVE: Tandem mass spectrometry (MS/MS) is being used for newborn screening since this laboratory testing technology increases the number of metabolic disorders that can be detected from dried blood-spot specimens. In the Community of Madrid, it was implemented in March 2011 and it includes 13 aminoacidopathies, fatty acid oxidation disorders and organic acidemias. The aim of this study was to describe our experience and evaluate the screening positive cases in a period of 9 years (2011-2019). METHODS: During the period of the study, a total of 592.822 neonates were screened with this expanded program by MS/MS in the Community of Madrid. Amino acids, acylcarnitines, and succinylacetone were quantified in all samples that met the quality criteria. Means, medians, percentiles and standard deviation of the analytes and ratios of interest were calculated. RESULTS: 901 patients (0,15 %) with a positive screening test were referred to clinical evaluation. 230 patients were diagnosed of 30 different inborn errors of metabolism (prevalence 1:2577), 11 of which were not included as a target in the Community of Madrid newborn screening program. The global positive predictive value was 25,6 %. During this period of time, two false negative cases were detected. The most prevalent disorders were phenylketonuria/hyperphenylalaninemia and medium chain acyl-CoA dehydrogenase deficiency (1:6444 and 1:13174 respectively). 93 % of the patients were detected in the presymptomatic stage. CONCLUSIONS: During the last 9 years a large number of cases of IEM have been detected with an acceptable global positive predictive value. These results confirm the utility of inborn errors of metabolism newborn screening as a public health program.

OBJETIVO: La tecnología de espectrometría de masas en tándem (MS/MS) en los programas de cribado neonatal ha permitido la detección de gran número de errores congénitos del metabolismo (ECM). En la comunidad de Madrid se implementó en marzo de 2011 incluyendo 13 aminoacidopatías, defectos de la ß-oxidación de ácidos grasos y acidemias orgánicas. El objetivo de este estudio fue describir nuestra experiencia y analizar los casos positivos de cribado en un periodo de 9 años (2011-2019). METODOS: Durante el periodo de estudio se realizó el cribado mediante MS/MS a 592822 recién nacidos en la Comunidad de Madrid. Se cuantificaron aminoácidos, acilcarnitinas y succinilacetona en todas las muestras que cumplieron los criterios de calidad. Se calcularon medias, medianas, percentiles y desviación típica de los analitos y ratios de interés. RESULTADOS: Se derivaron a las unidades clínicas de seguimiento por sospecha de una ECM un total de 901 (0,15 %) casos. Se confirmaron 230 casos de 30 ECM diferentes (prevalencia 1:2577), 11 de los cuales no eran inicialmente objetivo de detección del programa. El valor predictivo positivo global fue de 25,6 %. Durante este periodo se detectaron dos falsos negativos. Las enfermedades con mayor prevalencia fueron fenilcetonuria/hiperfenilalaninemia y deficiencia de acil-CoA deshidrogenasa de cadena media (1:6444 y 1: 13174 respectivamente). 93 % de los casos fueron detectados en fase presintomática. CONCLUSIONES: En estos 9 años de experiencia se han detectado numerosos casos de ECM con un valor predictivo positivo global aceptable. Estos resultados confirman la utilidad del cribado neonatal de ECM como programa de salud pública.

NGS-based expanded carrier screening for genetic disorders in North Indian population reveals unexpected results - a pilot study.

BACKGROUND: To determine the carrier frequency and pathogenic variants of common genetic disorders in the north Indian population by using next generation sequencing (NGS). METHODS: After pre-test counselling, 200 unrelated individuals (including 88 couples) were screened for pathogenic variants in 88 genes by NGS technology. The variants were classified as per American College of Medical Genetics criteria. Pathogenic and likely pathogenic variants were subjected to thorough literature-based curation in addition to the regular filters. Variants of unknown significance were not reported. Individuals were counselled explaining the implications of the results, and cascade screening was advised when necessary. RESULTS: Of the 200 participants, 52 (26%) were found to be carrier of one or more disorders. Twelve individuals were identified to be carriers for congenital deafness, giving a carrier frequency of one in 17 for one of the four genes tested (SLC26A4, GJB2, TMPRSS3 and TMC1 in decreasing order). Nine individuals were observed to be carriers for cystic fibrosis, with a frequency of one in 22. Three individuals were detected to be carriers for Pompe disease (frequency one in 67). None of the 88 couples screened were found to be carriers for the same disorder. The pathogenic variants observed in many disorders (such as deafness, cystic fibrosis, Pompe disease, Canavan disease, primary hyperoxaluria, junctional epidermolysis bullosa, galactosemia, medium chain acyl CoA deficiency etc.) were different from those commonly observed in the West. CONCLUSION: A higher carrier frequency for genetic deafness, cystic fibrosis and Pompe disease was unexpected, and contrary to the generally held view about their prevalence in Asian Indians. In spite of the small sample size, this study would suggest that population-based carrier screening panels for India would differ from those in the West, and need to be selected with due care. Testing should comprise the study of all the coding exons with its boundaries in the genes through NGS, as all the variants are not well characterized. Only study of entire coding regions in the genes will detect carriers with adequate efficiency, in order to reduce the burden of genetic disorders in India and other resource poor countries.

High prevalence of increased sitosterol levels in hypercholesterolemic children suggest underestimation of sitosterolemia incidence.

BACKGROUND: Sitosterolemia is an inherited lipid disorder which presents with elevated serum sitosterol and can result in an increased risk of premature cardiovascular disease. However, sitosterol cannot be accurately measured by routine diagnostic assays, meaning that sitosterolemia diagnosis can often be difficult, especially with many clinical features overlapping with familial hypercholesterolemia. With such complications resulting in increasing reports of misdiagnosis, the prevalence of sitosterolemia is predicted to be much higher than previously reported. METHODS: Gas chromatography-mass spectrometry was utilized to measure sitosterol levels of normocholesterolemic and hypercholesterolemic children. Subsequently, an epidemiologically determined cutoff level of sitosterol was calculated and applied to estimate the prevalence of children with increased sitosterol and identify potential sitosterolemia patients. Massively parallel sequencing was used to confirm the diagnosis in suspected patients. RESULTS: Samples from 109 normocholesterolemic and 220 hypercholesterolemic were tested for phytosterols. Sitosterol and campesterol levels were significantly increased in hypercholesterolemic children (mean 22.0±45.9 µmol/L for sitosterol and 26.0±32.8 µmol/L for campesterol) compared to normocholesterolemic children (mean 12.1±4.9 µmol/L for sistosterol and 14.8±6.7 µmol/L for campesterol). Via application of a cutoff of 35.9 µmol/L, the prevalence rates for increased and overtly increased sitosterol in hypercholesterolemic children were 6.4% and 1.4% respectively. Furthermore, 3 suspected sitosterolemia patients were identified, with 2 patients receiving molecular confirmation for sitosterolemia diagnosis. CONCLUSIONS: Our findings reaffirm that the prevalence of sitosterolemia is probably much higher than previously reported, which also indicates the significant risk of misdiagnosis of sitosterolemia with familial hypercholesterolemia. Special lipid testing including sitosterol, especially in children with uncontrolled hypercholesterolemia, is recommended in children in order to identify potential sitosterolemia patients that would otherwise be neglected.

Incidence of newborn screening disorders among 56632 infants in Central Saudi Arabia. A 6-year study.

OBJECTIVES: To determine the incidence of newborn screening (NBS) disorders and to study the key performance indicators of the program. METHODS: This retrospective single-center study enrolled all infants who underwent NBS from January 2012 to December 2017 at Prince Sultan Military Medical City, Riyadh, Saudi Arabia. We screened 17 NBS disorders. Blood samples were collected 24 hours after birth. If the initial result was positive, a second sample was collected. True positive cases were immediately referred for medical management. Data were extracted from laboratory computerized and non-computerized records using case report forms. RESULTS: During the study period, 56632 infants underwent NBS with a coverage rate of 100%. Thirty-eight cases were confirmed. The incidence of congenital hypothyroidism was 1:3775. The positive predictive value for the detection of congenital hypothyroidism was 11.8%. Propionic aciduria was the most common metabolic disorder, with an incidence of 1:14158. Very long-chain acyl CoA dehydrogenase deficiency and glutaric aciduria type 1 had an incidence of 1:18877 each. Phenylketonuria, biotinidase deficiency, maple syrup urine disease, and citrullinemia had an incidence of 1:28316 each. However, galactosemia and 3-methyl crotonyl carboxylase deficiency had the lowest incidence of 1:56632. CONCLUSION: The NBS coverage rate at our facility was 100%. Congenital hypothyroidism was the most frequently detected disorder with an incidence that matches worldwide figures. The incidence of other inherited disorders was consistent with regional figures.

Institutional experience of newborn screening for inborn metabolism disorders by tandem MS in the Turkish population.

Background The tandem mass spectrometry method in the screening of congenital metabolic disorders is not included in routine national newborn screening programmes in Turkey. To evaluate the distribution of acylcarnitines and amino acid levels in normal newborns, establish acylcarnitine and amino acid cut-off levels and further preliminary results of inherited metabolic disorders inferentially in the Turkish population. Methods Newborn screening tests performed by tandem MS from 2016 to 2018 were retrospectively reviewed. The study group included 17,066 newborns born in our hospitals located in various regions of Turkey. Blood samples were obtained from infants older than 24 h of age. Among the 17,066 newborns, the metabolic screening data of 9,994 full-term newborns (>37 weeks) were employed to obtain the percentile distribution of the normal population. The study group (17,066) was screened for 26 types of inborn error of metabolism. Results Our established cut-offs, were compared with the cut-offs determined by Region for Stork Study and Centers for Disease Control. Among the 26 screened disorders, a total of 12 cases (8 amino acid metabolism disorders, 1 urea cycle defect, 2 organic acidaemias and 1 fatty acid oxidation disorder) were identified. Conclusions Because of the high rate of consanguineous marriages in Turkey, the development of a nationwide screening panel is necessary for early detection and management of potentially treatable inherited metabolic disorders.

Genetic characteristics and follow-up of patients with fatty acid ß-oxidation disorders through expanded newborn screening in a Northern Chinese population.

Background Fatty acid ß-oxidation disorders (FAODs) include more than 15 distinct disorders and have a wide variety of symptoms, usually not evident between episodes of acute decompensation. After the introduction of newborn screening (NBS) using tandem mass spectrometry (MS/MS), early identification of FAODs has become feasible. We analyzed the MS/MS results in Tianjin, China during a six-year period to evaluate the incidence, disease spectrum, and genetic characteristics of FAODs. Methods We analyzed the MS/MS results for screening FAODs from May 2013 to December 2018 in Tianjin, China. Infants with positive screening results were confirmed through next-generation sequencing and validated by Sanger sequencing. Results A total of 220,443 infants were screened and 25 FAODs patients were identified (1:8,817). Primary carnitine deficiency (PCD) with an incidence rate up to 1:20,040 was the most common disorder among all FAODs. Recurrent mutations of relatively common diseases, like PCD and short-chain acyl-CoA dehydrogenase deficiency (SCADD), were identified. During the follow-up, two patients suffered from sudden death due to carnitine palmitoyl transferase-Ⅱ deficiency (CPT Ⅱ) and very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD). Conclusion Our data indicated that FAODs are relatively common in Tianjin and may even cause infant death in certain cases. The elucidated disease spectrum and genetic backgrounds elucidated in this study may contribute to the treatment and prenatal genetic counseling of FAODs.

Reference Intervals of Serum Non-Cholesterol Sterols by Gender in Healthy Japanese Individuals.

AIMS: The present study was conducted to establish a practical method for measuring non-cholesterol sterols and reference intervals of serum levels. METHODS: Healthy subjects (109 men and 151 women), four patients with sitosterolemia, and 10 heterozygous mutation carriers of ABCG5/ABCG8 genes were investigated. Then, three non-cholesterol sterols (sitosterol, campesterol, and lathosterol) of fasting serum samples were measured via a practical and highly sensitive gas chromatography (GC) method with 0.2 µg/mL as the lower limit of quantification. The coefficient of variation (CV) values for within-run reproducibility were 3.06%, 1.89%, and 1.77% for lathosterol, campesterol, and sitosterol, respectively. The CV values for between-run reproducibility were 2.81%, 2.06%, and 2.10% for lathosterol, campesterol, and sitosterol, respectively. RESULTS: The serum levels of sitosterol and campesterol were significantly higher in women than in men, whereas the serum levels of lathosterol were significantly higher in men than in women. Because of these gender difference, the determination of reference intervals of the three sterol values was performed by considering gender. The reference intervals of sitosterol, campesterol, and lathosterol were 0.99-3.88, 2.14-7.43, and 0.77-3.60 µg/mL in men and 1.03-4.45, 2.19-8.34, and 0.64-2.78 µg/mL in women, respectively. The serum levels of sitosterol and campesterol were higher in patients with sitosterolemia (94.3±47.3 and 66.3±36.6 µg/mL, respectively) than in healthy subjects. CONCLUSION: These results demonstrate a practical and highly sensitive GC method to measure non-cholesterol sterol levels and gender-segregated reference intervals of sitosterol, campesterol, and lathosterol in Japanese healthy subjects.

Análisis de casos positivos de cribado neonatal de errores congénitos del metabolismo en la Comunidad de Madrid / Newborn Screening Program in the Community of Madrid: evaluation of positive cases

OBJETIVO: La tecnología de espectrometría de masas en tándem (MS/MS) en los programas de cribado neonatal ha permitido la detección de gran número de errores congénitos del metabolismo (ECM). En la comunidad de Madrid se implementó en marzo de 2011 incluyendo 13 aminoacidopatías, defectos de la beta-oxidación de ácidos grasos y acidemias orgánicas. El objetivo de este estudio fue describir nuestra experiencia y analizar los casos positivos de cribado en un periodo de 9 años (2011-2019). MÉTODOS: Durante el periodo de estudio se realizó el cribado mediante MS/MS a 592822 recién nacidos en la Comunidad de Madrid. Se cuantificaron aminoácidos, acilcarnitinas y succinilacetona en todas las muestras que cumplieron los criterios de calidad. Se calcularon medias, medianas, percentiles y desviación típica de los analitos y ratios de interés. RESULTADOS: Se derivaron a las unidades clínicas de seguimiento por sospecha de una ECM un total de 901 (0,15 %) casos. Se confirmaron 230 casos de 30 ECM diferentes (prevalencia 1:2577), 11 de los cuales no eran inicialmente objetivo de detección del programa. El valor predictivo positivo global fue de 25,6 %. Durante este periodo se detectaron dos falsos negativos. Las enfermedades con mayor prevalencia fueron fenilcetonuria/hiperfenilalaninemia y deficiencia de acil-CoA deshidrogenasa de cadena media (1:6444 y 1: 13174 respectivamente). 93 % de los casos fueron detectados en fase presintomática. CONCLUSIONES: En estos 9 años de experiencia se han detectado numerosos casos de ECM con un valor predictivo positivo global aceptable. Estos resultados confirman la utilidad del cribado neonatal de ECM como programa de salud pública

OBJECTIVE: Tandem mass spectrometry (MS/MS) is being used for newborn screening since this laboratory testing technology increases the number of metabolic disorders that can be detected from dried blood-spot specimens. In the Community of Madrid, it was implemented in March 2011 and it includes 13 aminoacidopathies, fatty acid oxidation disorders and organic acidemias. The aim of this study was to describe our experience and evaluate the screening positive cases in a period of 9 years (2011-2019). METHODS: During the period of the study, a total of 592.822 neonates were screened with this expanded program by MS/MS in the Community of Madrid. Amino acids, acylcarnitines, and succinylacetone were quantified in all samples that met the quality criteria. Means, medians, percentiles and standard deviation of the analytes and ratios of interest were calculated. RESULTS: 901 patients (0,15 %) with a positive screening test were referred to clinical evaluation. 230 patients were diagnosed of 30 different inborn errors of metabolism (prevalence 1:2577), 11 of which were not included as a target in the Community of Madrid newborn screening program. The global positive predictive value was 25,6 %. During this period of time, two false negative cases were detected. The most prevalent disorders were phenylketonuria/hyperphenylalaninemia and medium chain acyl-CoA dehydrogenase deficiency (1:6444 and 1:13174 respectively). 93 % of the patients were detected in the presymptomatic stage. CONCLUSIONS: During the last 9 years a large number of cases of IEM have been detected with an acceptable global positive predictive value. These results confirm the utility of inborn errors of metabolism newborn screening as a public health program

Neutral lipid storage disease with myopathy in China: a large multicentric cohort study.

BACKGROUND: Neutral lipid storage disease with myopathy (NLSDM) is a rare clinical heterogeneous disorder caused by mutations in the patatin-like phospholipase domain-containing 2 (PNPLA2) gene. NLSDM usually presents skeletal myopathy, cardiomyopathy and the multiple organs dysfunction. Around 50 cases of NLSDM have been described worldwide, whereas the comprehensive understanding of this disease are still limited. We therefore recruit NLSDM patients from 10 centers across China, summarize the clinical, muscle imaging, pathological and genetic features, and analyze the genotype-phenotype relationship. RESULTS: A total of 45 NLSDM patients (18 men and 27 women) were recruited from 40 unrelated families. Thirteen patients were born from consanguineous parents. The phenotypes were classified as asymptomatic hyperCKemia (2/45), pure skeletal myopathy (18/45), pure cardiomyopathy (4/45), and the combination of skeletal myopathy and cardiomyopathy (21/45). Right upper limb weakness was the early and prominent feature in 61.5% of patients. On muscle MRI, the long head of the biceps femoris, semimembranosus and adductor magnus on thighs, the soleus and medial head of the gastrocnemius on lower legs showed the most severe fatty infiltration. Thirty-three families were carrying homozygous mutations, while seven families were carrying compound heterozygous mutations. A total of 23 mutations were identified including 11 (47.8%) point mutations, eight (34.8%) deletions and four (17.4%) insertions. c.757 + 1G > T, c.245G > A and c.187 + 1G > A were the three most frequent mutations. Among four groups of phenotypes, significant differences were shown in disease onset (< 20 years versus ≥20 years old, p = 0.003) and muscle pathology (with rimmed vacuoles versus without rimmed vacuoles, p = 0.001). PNPLA2 mutational type or functional defects did not show great impact on phenotypes. CONCLUSION: We outline the clinical and genetic spectrum in a large cohort of NLSDM patients. Selective muscle fatty infiltration on posterior compartment of legs are characteristic of NLSDM. Chinese patients present with distinctive and relative hotspot PNPLA2 mutations. The disease onset age and pathological appearance of rimmed vacuoles are proved to be related with the clinical manifestations. The phenotypes are not strongly influenced by genetic defects, suggesting the multiple environmental risk factors in the development of NLSDM.

Health services use among children diagnosed with medium-chain acyl-CoA dehydrogenase deficiency through newborn screening: a cohort study in Ontario, Canada.

BACKGROUND: We describe early health services utilization for children diagnosed with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency through newborn screening in Ontario, Canada, relative to a screen negative comparison cohort. METHODS: Eligible children were identified via newborn screening between April 1, 2006 and March 31, 2010. Age-stratified rates of physician encounters, emergency department (ED) visits and inpatient hospitalizations to March 31, 2012 were compared using incidence rate ratios (IRR) and incidence rate differences (IRD). We used negative binomial regression to adjust IRRs for sex, gestational age, birth weight, socioeconomic status and rural/urban residence. RESULTS: Throughout the first few years of life, children with MCAD deficiency (n = 40) experienced statistically significantly higher rates of physician encounters, ED visits, and hospital stays compared with the screen negative cohort. The highest rates of ED visits and hospitalizations in the MCAD deficiency cohort occurred from 6 months to 2 years of age (ED use: 2.1-2.5 visits per child per year; hospitalization: 0.5-0.6 visits per child per year), after which rates gradually declined. CONCLUSIONS: This study confirms that young children with MCAD deficiency use health services more frequently than the general population throughout the first few years of life. Rates of service use in this population gradually diminish after 24 months of age.

Value of genetic analysis for confirming inborn errors of metabolism detected through the Spanish neonatal screening program.

The present work describes the value of genetic analysis as a confirmatory measure following the detection of suspected inborn errors of metabolism in the Spanish newborn mass spectrometry screening program. One hundred and forty-one consecutive DNA samples were analyzed by next-generation sequencing using a customized exome sequencing panel. When required, the Illumina extended clinical exome panel was used, as was Sanger sequencing or transcriptional profiling. Biochemical tests were used to confirm the results of the genetic analysis. Using the customized panel, the metabolic disease suspected in 83 newborns (59%) was confirmed. In three further cases, two monoallelic variants were detected for two genes involved in the same biochemical pathway. In the remainder, either a single variant or no variant was identified. Given the persistent absence of biochemical alterations, carrier status was assigned in 39 cases. False positives were recorded for 11. In five cases in which the biochemical pattern was persistently altered, further genetic analysis allowed the detection of two variants affecting the function of BCAT2, ACSF3, and DNAJC12, as well as a second, deep intronic variant in ETFDH or PTS. The present results suggest that genetic analysis using extended next-generation sequencing panels can be used as a confirmatory test for suspected inborn errors of metabolism detected in newborn screening programs. Biochemical tests can be very helpful when a diagnosis is unclear. In summary, simultaneous genomic and metabolomic analyses can increase the number of inborn errors of metabolism that can be confirmed following suggestive newborn screening results.

Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) in the Irish Paediatric Population.

Aim This study aims to investigate the disease frequency of Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) among the Irish population. Methods Children (<18 years) with MCADD were identified via the National Centre for Inherited Metabolic Disorders and the metabolic laboratory at Temple Street Children's University Hospital. Central Statistics Office population data was used to calculate epidemiological figures. Results From 1998 to 2016, 17 children (<18 years) were diagnosed with MCADD including two patients whose initial presentation was fatal. The mean age at initial presentation was 1.48 years (Range: 0.005 to 2.86). The incidence was 1:71650 with mortality at 15.38%. No child subsequently died post diagnosis. The common c.985A>G mutation accounted for 88% of alleles. Conclusion The incidence of MCADD in Ireland is lower than global estimates. The potential for under-ascertainment and late diagnosis of cases exists in Ireland and is of concern for a treatable condition with a significant mortality when undiagnosed. The authors welcome the introduction of MCADD to the National Newborn Bloodspot Screening Program.