Uterine leiomyoma with fumarate hydratase deficiency: A case report.

RATIONALE: Hereditary leiomyomatosis and renal cell carcinoma is an uncommon autosomal dominant disease caused by mutations in the fumarate hydratase (FH) gene. They usually demonstrated multiple uterine myomas and preformed surgical procedures for myomectomy and/or hysterectomy 10 years earlier than sporadic myomas due to early development. This case report describes a woman with multiple uterine leiomyomas diagnosed with FH deficiency. PATIENT CONCERNS: A 37-year-old woman visited a gynecological clinic for the discovery of uterine leiomyoma for more than 1 year. The size of the largest grew from 42 × 27 × 46 to 98 × 85 × 113 mm in 1 year. She had a history of surgery for breast cancer and thyroid cancer but denied a history of uterine leiomyoma in her family. DIAGNOSIS AND INTERVENTIONS: The patient underwent successful transabdominal hysterectomy. The pathological results showed multiple uterine leiomyomas (partly cellular leiomyomas) with scattered large bizarre giant cells. Immunohistochemistry results demonstrated FH deficiency. OUTCOMES: On follow-up, the patient did not have any complications. She was finally referred to the oncologists and urologists for follow-up. LESSONS: Gynecologists should be aware that early onset uterine leiomyoma presenting as large, multiple, and symptomatic lesion, may be associated with FH deficiency.

Novel mutations associated with carnitine-acylcarnitine translocase and carnitine palmitoyl transferase 2 deficiencies in Malaysia.

OBJECTIVE: Carnitine-acylcarnitine Translocase (CACT) deficiency (OMIM 212138) and carnitine palmitoyl transferase 2 (CPT2) deficiency (OMIM 60065050) are rare inherited disorders of mitochondrial long chain fatty acid oxidation. The aim of our study is to review the clinical, biochemical and molecular characteristics in children diagnosed with CACT and CPT2 deficiencies in Malaysia. DESIGN AND METHODS: This is a retrospective study. We reviewed medical records of six patients diagnosed with CACT and CPT2 deficiencies. They were identified from a selective high-risk screening of 50,579 patients from January 2010 until Jun 2020. RESULTS: All six patients had either elevation of the long chain acylcarnitines and/or an elevated (C16 + C18:1)/C2 acylcarnitine ratio. SLC25A20 gene sequencing of patient 1 and 6 showed a homozygous splice site mutation at c.199-10 T > G in intron 2. Two novel mutations at c.109C > T p. (Arg37*) in exon 2 and at c.706C > T p. (Arg236*) in exon 7 of SLC25A20 gene were found in patient 2. Patient 3 and 4 (siblings) exhibited a compound heterozygous mutation at c.638A > G p. (Asp213Gly) and novel mutation c.1073 T > G p. (Leu358Arg) in exon 4 of CPT2 gene. A significant combined prevalence at 0.01% of CACT and CPT2 deficiencies was found in the symptomatic Malaysian patients. CONCLUSIONS: The use of the (C16 + C18:1)/C2 acylcarnitine ratio in dried blood spot in our experience improves the diagnostic specificity for CACT/CPT2 deficiencies over long chain acylcarnitine (C16 and C18:1) alone. DNA sequencing for both genes aids in confirming the diagnosis.

Validation of plasma amino acid profile using UHPLC-mass spectrometer (QDa) as a screening method in a metabolic disorders reference centre: Performance and accreditation concerns.

INTRODUCTION: Amino acid (AA) analysis in plasma is essential for diagnosis and monitoring of inborn errors of metabolism (IEM). The efficacy of patient management is governed by the rapidity of AA profile availability, along with the robustness of the method. French quality guidelines and progress made in analytical techniques have led biologists to develop AA profile exploration via mass spectrometry (MS). OBJECTIVES: The aim of this study was to validate an analytical method with a single quadrupole mass spectrometer (MS) and to suggest reference values in regard to French quality and IEM society recommendations. DESIGN AND METHODS: Plasma samples from patients were deproteinised and derivatised with AccqTag™ reagent. Analysis was performed by reverse-phase chromatography coupled to QDA detector. We evaluated accuracy, intra-days and inter-days precision and limit of quantification by the ß-expectation tolerance interval method for 27 AA. Method comparison was performed with the standard method (ion exchange chromatography, IEC) on Jeol Aminotac® and to tandem MS. Reference values were established on AA concentrations of the cohort of patients who had no IEM. RESULTS: Our method allowed the separations of almost all amino acids with a total run time of 12 min. Separation of isoleucine and alloisoleucine was incomplete (R = 0.55) but without impact on biological interpretation. Precision, accuracy and quantification were satisfactory (intra-days coefficient of variation (CV) was <5%, inter-days precision CV <10% and accuracy <15%). The limits of quantification were validated between 1 and 900 µmol/L. Results were comparable between the new method and IEC. CONCLUSION: Ultimately, we validated a rapid method on plasma for quantifying 27 amino acids that can be used in routine practice, according to French quality laboratories and SFEIM (French Society of Inborn Error of Metabolism) recommendations. Furthermore, estimated reference values were similar to those found in published studies focusing on other methods. Despite a lower specificity compared to tandem MS, the simplicity and rapidity of our method are the main advantage of this technique and place it as a major tool in IEM diagnosis and management.

Sensitivity of turtles to anticoagulant rodenticides: Risk assessment for green sea turtles (Chelonia mydas) in the Ogasawara Islands and comparison of warfarin sensitivity among turtle species.

Although anticoagulant rodenticides (ARs) are effectively used for the control of invasive rodents, nontarget species are also frequently exposed to ARs and secondary poisonings occur widely. However, little data is available on the effects of ARs, especially on marine organisms. To evaluate the effects of ARs on marine wildlife, we chose green sea turtles (Chelonia mydas), which are one of the most common marine organisms around the Ogasawara islands, as our primary study species. The sensitivity of these turtles to ARs was assessed using both in vivo and in vitro approaches. We administered 4 mg/kg of warfarin sodium either orally or intravenously to juvenile green sea turtles. The turtles exhibited slow pharmacokinetics, and prolongation of prothrombin time (PT) was observed only with intravenous warfarin administration. We also conducted an in vitro investigation using liver microsomes from green sea turtles, and two other turtle species (softshell turtle and red-eared slider) and rats. The cytochrome P450 metabolic activity in the liver of green sea turtles was lower than in rats. Additionally, vitamin K epoxide reductase (VKOR), which is the target enzyme of ARs, was inhibited by warfarin in the turtles at lower concentration levels than in rats. These data indicate that turtles may be more sensitive to ARs than rats. We expect that these findings will be helpful for sea turtle conservation following accidental AR-broadcast incidents.

METABOLIC CONTROL AND BODY COMPOSITION OF CHILDREN AND ADOLESCENTS WITH PHENYLKETONURIA.

OBJECTIVE: To characterize metabolic control and verify whether it has any relation with socioeconomic, demographic, and body composition variables in children and adolescents with phenylketonuria (PKU) diagnosed in the neonatal period. METHODS: This cohort study collected retrospective data of 53 phenylketonuric children and adolescents. Data on family income, housing, and mother's age and schooling level were collected, and anthropometric measures of body composition and distribution were taken. All dosages of phenylalanine (Phe) from the last five years (2015-2019) were evaluated and classified regarding their adequacy (cutoffs: 0-12 years: 2-6 mg/dL; 12-19 years: 2-10 mg/dL). Adequate metabolic control was considered if ≥7%) of the dosages were within desired ranges. RESULTS: The mean (±standard deviation) age in the last year was 10.1±4.6 years. Most of them were under 12 years old (33/53; 62.3%) and had the classic form of the disease (39/53; 73.6%). Better metabolic control was observed among adolescents (68.4 versus 51.4%; p=0.019). Overweight was found in 9/53 (17%) and higher serum Phe levels (p<0.001) were found in this group of patients. Metabolic control with 70% or more Phe level adequacy decreased along with the arm muscle area (AMA) (ptendency=0.042), being 70.0% among those with low reserve (low AMA), and 18.5% among those with excessive reserve (high AMA). CONCLUSIONS: Adequate metabolic control was observed in most patients. The findings suggest that, in this sample, the levels of phenylalanine may be related to changes in body composition.

Cardiovascular manifestations of intermediate and major hyperhomocysteinemia due to vitamin B12 and folate deficiency and/or inherited disorders of one-carbon metabolism: a 3.5-year retrospective cross-sectional study of consecutive patients.

BACKGROUND: The association of moderate hyperhomocysteinemia (HHcy) (15-30 µmol/L) with cardiovascular diseases (CVD) has been challenged by the lack of benefit of vitamin supplementation to lowering homocysteine. Consequently, the results of interventional studies have confused the debate regarding the management of patients with intermediate/severe HHcy. OBJECTIVE: We sought to evaluate the association of intermediate (30-100 µmol/L) and severe (>100 µmol/L) HHcy related to vitamin deficiencies and/or inherited disorders with CVD outcomes. METHODS: We performed a retrospective cross-sectional study on consecutive patients who underwent a homocysteine assay in a French University Regional Hospital Center. Patients with CVD outcomes were assessed for vitamin B12, folate, Hcy, methylmalonic acid, and next-generation clinical exome sequencing. RESULTS: We evaluated 165 patients hospitalized for thromboembolic and other cardiovascular (CV) manifestations among 1006 patients consecutively recruited. Among them, 84% (138/165) had Hcy >30 µmol/L, 27% Hcy >50 µmol/L (44/165) and 3% Hcy >100 µmol/L (5/165). HHcy was related to vitamin B12 and/or folate deficiency in 55% (87/165), mutations in one or more genes of one-carbon and/or vitamin B12 metabolisms in 11% (19/165), and severe renal failure in 15% (21/141) of the studied patients. HHcy was the single vascular risk retrieved in almost 9% (15/165) of patients. Sixty % (101/165) of patients received a supplementation to treat HHcy, with a significant decrease in median Hcy from 41 to 17 µmol/L (IQR: 33.6-60.4 compared with 12.1-28). No recurrence of thromboembolic manifestations was observed after supplementation and antithrombotic treatment of patients who had HHcy as a single risk, after ∼4 y of follow-up. CONCLUSION: The high frequency of intermediate/severe HHcy differs from the frequent moderate HHcy reported in previous observational studies of patients with pre-existing CVD. Our study points out the importance of diagnosing and treating nutritional deficiencies and inherited disorders to reverse intermediate/severe HHcy associated with CVD outcomes.

Metabolic control and body composition of children and adolescents with phenylketonuria / Controle metabólico e composição corporal de crianças e adolescentes com diagnóstico neonatal de fenilcetonúria

ABSTRACT Objective: To characterize metabolic control and verify whether it has any relation with socioeconomic, demographic, and body composition variables in children and adolescents with phenylketonuria (PKU) diagnosed in the neonatal period. Methods: This cohort study collected retrospective data of 53 phenylketonuric children and adolescents. Data on family income, housing, and mother's age and schooling level were collected, and anthropometric measures of body composition and distribution were taken. All dosages of phenylalanine (Phe) from the last five years (2015-2019) were evaluated and classified regarding their adequacy (cutoffs: 0-12 years: 2-6 mg/dL; 12-19 years: 2-10 mg/dL). Adequate metabolic control was considered if ≥7%) of the dosages were within desired ranges. Results: The mean (±standard deviation) age in the last year was 10.1±4.6 years. Most of them were under 12 years old (33/53; 62.3%) and had the classic form of the disease (39/53; 73.6%). Better metabolic control was observed among adolescents (68.4 versus 51.4%; p=0.019). Overweight was found in 9/53 (17%) and higher serum Phe levels (p<0.001) were found in this group of patients. Metabolic control with 70% or more Phe level adequacy decreased along with the arm muscle area (AMA) (ptendency=0.042), being 70.0% among those with low reserve (low AMA), and 18.5% among those with excessive reserve (high AMA). Conclusions: Adequate metabolic control was observed in most patients. The findings suggest that, in this sample, the levels of phenylalanine may be related to changes in body composition.

RESUMO Objetivo: Caracterizar o controle metabólico e verificar se existe relação entre ele, variáveis socioeconômicas, demográficas e composição corporal de crianças e adolescentes com fenilcetonúria (FNC) diagnosticada no período neonatal. Métodos: Coorte com coleta retrospectiva de dados de 53 crianças e adolescentes fenilcetonúricos. Foram coletados dados de renda familiar, moradia, idade e escolaridade materna e realizaram-se medidas antropométricas de composição e distribuição corporal. Todas as dosagens de fenilalanina (Fal) dos últimos cinco anos (2015-2019) foram avaliadas e classificadas quanto à adequação (cortes: 0-12 anos: 2-6 mg/dL; 12-19 anos: 2-10 mg/dL). A proporção de dosagens adequadas ≥70% foi considerada como controle metabólico adequado. Resultados: A média (±desvio padrão) de idade, no último ano, foi de 10,1±4,6 anos. A maioria tinha menos de 12 anos (33/53; 62,3%) e apresentava a forma clássica da doença (39/53; 73,6%). Observou-se melhor controle metabólico entre os adolescentes (68,4 vs. 51,4%; p=0,019). Excesso de peso foi encontrado em 9/53 (17%) e maiores níveis séricos de Fal foram descritos nesse grupo (p<0,001). O percentual de controle metabólico com 70% ou mais de adequação dos níveis de Fal foi decrescente de acordo com a área muscular do braço (AMB; ptendência=0,042), sendo de 70% entre os de baixa reserva (AMB reduzida) e de 18,5% entre os com excesso (AMB elevada). Conclusões: Observou-se controle metabólico adequado na maioria dos avaliados e os achados sugerem que, nesta amostra, os níveis de fenilalanina podem estar relacionados com alterações da composição corporal.

[Impact of the inclusion of second-tier tests in the newborn screening program of Catalonia and in other international programs.] / Impacto de la inclusión de pruebas de segundo nivel en el programa de cribado neonatal de Cataluña y en otros programas internacionales.

OBJECTIVE: Newborn screening programmes (NBSP) have experienced a qualitative breakthrough due to the implementation of tandem mass spectrometry. However, the tests used give rise to false positives (FP) generating an excessive request for second samples with the consequent anxiety of the families. In order to avoid this problem several programmes have developed second-tier tests (2TT). METHODS: This article presents our experience in the implementation of 2TT in the NBSP of Catalonia, as well as in other international programmes. RESULTS: From 2004 to the present, 2TT tests have been developed for more than 30 diseases. The use of 2TT helps to decrease the FP rate and increase the positive predictive value (PPV). In the NBSP of Catalonia, the implementation of 2TT for the detection of methylmalonic and propionic acidemias, homocystinurias, maple syrup disease and citrulinaemia, has managed to increase the PPV to 95% and decrease the PF rate to less than 0.01%. In cystic fibrosis, the application of 2TT slightly increases PPV but with a significant decrease in the request for second samples and in the number of cases referred to clinical units. CONCLUSIONS: The introduction of 2TT in the NBSP allows to reduce considerably the FP, decreases the number of requested samples, as well as both anxiety and stress of the families, at the same time that the hospital costs are reduced and the PPV is increased, improving notably the efficiency of the NBSP.

OBJETIVO: Los programas de cribado neonatal (PCN) han experimentado un gran avance cualitativo debido a la implementación de la espectrometría de masas en tándem. Sin embargo, las pruebas utilizadas dan lugar a falsos positivos (FP) generando una excesiva solicitud de segundas muestras con la consiguiente ansiedad de las familias. Con el fin de evitar este problema diversos programas han desarrollado pruebas de segundo nivel (2TT). METODOS: En este artículo se presenta nuestra experiencia en la implementación de 2TT en el PCN de Cataluña, así como en otros programas internacionales. RESULTADOS: Desde el año 2004 hasta la actualidad se han desarrollado pruebas de 2TT para más de 30 enfermedades. La utilización de 2TT ayuda a disminuir la tasa de FP y aumentar el valor predictivo positivo (VPP). En el PCN de Cataluña, la implementación de 2TT para la detección de acidemias metilmalónicas y propiónica, homocistinurias, jarabe de arce y citrulinemia, ha conseguido aumentar el VPP a un 95% y disminuir la tasa de FP a menos del 0,01%. En la fibrosis quística la aplicación de 2TT aumenta ligeramente el VPP pero con disminución significativa de la solicitud de segundas muestras y de los casos referidos a las unidades clínicas. CONCLUSIONES: La introducción de los 2TT en los PCN permite reducir considerablemente los FP, disminuye el número de muestras solicitadas, así como la ansiedad y el estrés de las familias, a la vez que se reducen los costes hospitalarios y se aumenta el VPP, mejorando notablemente la eficiencia de los PCN.

[Recommendations for aminoacids chromatography analysis]. / Recommandations concernant l'analyse de la chromatographie des acides aminés.

Biochemical diagnosis of hereditary metabolic diseases requires the detection and simultaneous identification of a large number of compounds, hence the interest in metabolic profiles. Amino acid chromatography allows the identification and quantification of more than forty compounds. As part of the accreditation process for medical biology examinations according to standard NF EN ISO 15189, the group from SFEIM recommends an approach to accredit amino acid chromatography. Validation parameters and recommendations are discussed in this specific framework.

Expanding phenotypic and mutational spectra of mitochondrial HMG-CoA synthase deficiency.

Mitochondrial 3-hydroxy-3 methylglutaryl-CoA synthase-2 deficiency (HMGCS2D) is a rare autosomal recessive inborn error of hepatic ketogenesis, caused by mutations in HMGCS2. As its clinical and laboratory manifestations resemble many other metabolic disorders, HMGCS2D definite diagnosis presents a challenge, frequently requiring molecular tests. Only 26 patients with HMGCS2 mutations have been previously described, and this study reports the first two unrelated Thai patients, a 9-month-old male and an 8-month-old female, with HMGCS2D. During acute episodes, steatorrhea and dyslipidemia occurred, both previously unreported. Increased serum levels of triglycerides, very low density lipoproteins (VLDL), and low density lipoproteins (LDL), along with a decreased serum level of HDL were found. Both patients had hypophosphatemic encephalopathy, and the female had metabolic acidosis without hypoglycemia. Trio whole-exome sequencing (WES) revealed that the male harbored two HMGCS2 mutations, a novel c.1480C>T (p.Arg494*) and a previously reported c.1502G>C (p.Arg501Pro), while the female was compound heterozygous for the c.1502G>C (p.Arg501Pro) and a previously reported mutation, c.520T>C (p.Phe174Leu). Interestingly, c.1502G>C (p.Arg501Pro) was not only found in both of our patients but also detected heterozygously in 9 out of 1081 unrelated individuals (allele frequency of 9/2162; 0.42%) in our in-house Thai exome database. Discovery of this common mutation suggests there could be about 14 babies with HMGCS2D within 800,000 newborns in Thailand annually. Therefore, awareness of HMGCS2D among medical personnel in Thailand should be raised.

[Recommendations for acylcarnitine profile analysis]. / Recommandations concernant l'analyse du profil des acylcarnitines.

Biochemical diagnosis of hereditary metabolic diseases requires the detection and simultaneous identification of a large number of compounds, hence the interest in metabolic profiles. Acylcarnitine profile allows the identification and quantification of more than thirty compounds. As part of the accreditation process for medical biology examinations according to standard NF EN ISO 15189, the group from SFEIM recommends an approach to accredit acylcarnitine profile. Validation parameters and recommendations are discussed in this specific framework.

Effects of fasting, feeding and exercise on plasma acylcarnitines among subjects with CPT2D, VLCADD and LCHADD/TFPD.

BACKGROUND: The plasma acylcarnitine profile is frequently used as a biochemical assessment for follow-up in diagnosed patients with fatty acid oxidation disorders (FAODs). Disease specific acylcarnitine species are elevated during metabolic decompensation but there is clinical and biochemical heterogeneity among patients and limited data on the utility of an acylcarnitine profile for routine clinical monitoring. METHODS: We evaluated plasma acylcarnitine profiles from 30 diagnosed patients with long-chain FAODs (carnitine palmitoyltransferase-2 (CPT2), very long-chain acyl-CoA dehydrogenase (VLCAD), and long-chain 3-hydroxy acyl-CoA dehydrogenase or mitochondrial trifunctional protein (LCHAD/TFP) deficiencies) collected after an overnight fast, after feeding a controlled low-fat diet, and before and after moderate exercise. Our purpose was to describe the variability in this biomarker and how various physiologic states effect the acylcarnitine concentrations in circulation. RESULTS: Disease specific acylcarnitine species were higher after an overnight fast and decreased by approximately 60% two hours after a controlled breakfast meal. Moderate-intensity exercise increased the acylcarnitine species but it varied by diagnosis. When analyzed for a genotype/phenotype correlation, the presence of the common LCHADD mutation (c.1528G > C) was associated with higher levels of 3-hydroxyacylcarnitines than in patients with other mutations. CONCLUSIONS: We found that feeding consistently suppressed and that moderate intensity exercise increased disease specific acylcarnitine species, but the response to exercise was highly variable across subjects and diagnoses. The clinical utility of routine plasma acylcarnitine analysis for outpatient treatment monitoring remains questionable; however, if acylcarnitine profiles are measured in the clinical setting, standardized procedures are required for sample collection to be of value.

Untargeted metabolomics as an unbiased approach to the diagnosis of inborn errors of metabolism of the non-oxidative branch of the pentose phosphate pathway.

Inborn errors of metabolism (IEM) involving the non-oxidative pentose phosphate pathway (PPP) include the two relatively rare conditions, transketolase deficiency and transaldolase deficiency, both of which can be difficult to diagnosis given their non-specific clinical presentations. Current biochemical testing approaches require an index of suspicion to consider targeted urine polyol testing. To determine whether a broad-spectrum biochemical test could accurately identify a specific metabolic pattern defining IEMs of the non-oxidative PPP, we employed the use of clinical metabolomic profiling as an unbiased novel approach to diagnosis. Subjects with molecularly confirmed IEMs of the PPP were included in this study. Targeted quantitative analysis of polyols in urine and plasma samples was accomplished with chromatography and mass spectrometry. Semi-quantitative unbiased metabolomic analysis of urine and plasma samples was achieved by assessing small molecules via liquid chromatography and high-resolution mass spectrometry. Results from untargeted and targeted analyses were then compared and analyzed for diagnostic acuity. Two siblings with transketolase (TKT) deficiency and three unrelated individuals with transaldolase (TALDO) deficiency were identified for inclusion in the study. For both IEMs, targeted polyol testing and untargeted metabolomic testing on urine and/or plasma samples identified typical perturbations of the respective disorder. Additionally, untargeted metabolomic testing revealed elevations in other PPP metabolites not typically measured with targeted polyol testing, including ribonate, ribose, and erythronate for TKT deficiency and ribonate, erythronate, and sedoheptulose 7-phosphate in TALDO deficiency. Non-PPP alternations were also noted involving tryptophan, purine, and pyrimidine metabolism for both TKT and TALDO deficient patients. Targeted polyol testing and untargeted metabolomic testing methods were both able to identify specific biochemical patterns indicative of TKT and TALDO deficiency in both plasma and urine samples. In addition, untargeted metabolomics was able to identify novel biomarkers, thereby expanding the current knowledge of both conditions and providing further insight into potential underlying pathophysiological mechanisms. Furthermore, untargeted metabolomic testing offers the advantage of having a single effective biochemical screening test for identification of rare IEMs, like TKT and TALDO deficiencies, that may otherwise go undiagnosed due to their generally non-specific clinical presentations.

Coincidence of 3-methylglutaconic aciduria and duplication 5q - a case report and literature review.

3-methylglutaconic aciduria includes a heterogeneous group of inborn errors of metabolism. The disease may have various clinical presentations, as can duplication 5q. We present the case of a 13-year-old boy with 3-methylglutaconic aciduria and duplication 5q. The main symptoms included myopathy, weakness, spastic paresis intensified mostly in the lower limbs, and intellectual disability. Additional studies showed elevated levels of 3-methylglutaconic acid in urine and ammonia in plasma. A duplication in region 5q23.3q31.1 was found in array-based comparative genomic hybridization. Next-generation sequencing did not reveal any pathological mutation. On the basis of the clinical picture and the results of biochemical and genetic tests 3-methylglutaconic aciduria type IV with duplication 5q was diagnosed.

Precision of a Clinical Metabolomics Profiling Platform for Use in the Identification of Inborn Errors of Metabolism.

BACKGROUND: The application of whole-exome sequencing for the diagnosis of genetic disease has paved the way for systems-based approaches in the clinical laboratory. Here, we describe a clinical metabolomics method for the screening of metabolic diseases through the analysis of a multi-pronged mass spectrometry platform. By simultaneously measuring hundreds of metabolites in a single sample, clinical metabolomics offers a comprehensive approach to identify metabolic perturbations across multiple biochemical pathways. METHODS: We conducted a single- and multi-day precision study on hundreds of metabolites in human plasma on 4, multi-arm, high-throughput metabolomics platforms. RESULTS: The average laboratory coefficient of variation (CV) on the 4 platforms was between 9.3 and 11.5% (median, 6.5-8.4%), average inter-assay CV on the 4 platforms ranged from 9.9 to 12.6% (median, 7.0-8.3%) and average intra-assay CV on the 4 platforms ranged from 5.7 to 6.9% (median, 3.5-4.4%). In relation to patient sample testing, the precision of multiple biomarkers associated with IEM disorders showed CVs that ranged from 0.2 to 11.0% across 4 analytical batches. CONCLUSIONS: This evaluation describes single and multi-day precision across 4 identical metabolomics platforms, comprised each of 4 independent method arms, and reproducibility of the method for the measurement of key IEM metabolites in patient samples across multiple analytical batches, providing evidence that the method is robust and reproducible for the screening of patients with inborn errors of metabolism.

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.

Rare causes of hypoglycemia in adults.

Hypoglycemia is defined by a low blood glucose level associated to clinical symptoms. Hypoglycemia may be related to treatment of diabetes, but also to drugs, alcohol, critical illness, cortisol insufficiency including hypopituitarism, insulinoma, bariatric or gastric surgery, pancreas transplantation or glucagon deficiency, or may be surreptitious. Some hypoglycemic episodes remain unexplained, and genetic, paraneoplastic and immune causes should be considered. Genetic causes may be related to endogenous hyperinsulinism and to inborn errors of metabolism (IEM). Endogenous hyperinsulinism is related to monogenic congenital hyperinsulinism, and especially to mutations of the glucokinase-activating gene or of insulin receptors, both characterised by postprandial hypoglycemia with major hyperinsulinism. In adulthood, IEM-related hypoglycemia can persist in a previously diagnosed childhood disease or may be a presenting sign. It is suggested by systemic involvement (rhabdomyolysis after fasting or exercising, heart disease, hepatomegaly), sometimes associated to a family history of hypoglycemia. The timing of hypoglycemic episodes with respect to the last meal also helps to orientate diagnosis. Fasting hypoglycemia may be related to type 0, I or III glycogen synthesis disorder, fatty acid oxidation or gluconeogenesis disorder. Postprandial hypoglycemia may be related to inherited fructose intolerance. Exercise-induced hyperinsulinism is mainly related to activating mutation of the SLC16A1 gene. Besides exceptional ectopic insulin secretion, paraneoplastic causes involve NICTH (Non-Islet-Cell Tumour Hypoglycemia), caused by Big-IGF2 secretion by a large tumour, with low blood levels of insulin, C-peptide and IGF1. Autoimmune causes involve antibodies against insulin (HIRATA syndrome), especially in case of Graves' disease, or against the insulin receptor. Medical history, timing, and insulin level orientate the diagnosis.