A novel pathogenic variant in the carnitine transporter gene, SLC22A5, in association with metabolic carnitine deficiency and cardiomyopathy features.

BACKGROUND: Primary carnitine deficiency (PCD) denotes low carnitine levels with an autosomal recessive pattern of inheritance. Cardiomyopathy is the most common cardiac symptom in patients with PCD, and early diagnosis can prevent complications. Next-generation sequencing can identify genetic variants attributable to PCD efficiently. OBJECTIVE: We aimed to detect the genetic cause of the early manifestations of hypertrophic cardiomyopathy and metabolic abnormalities in an Iranian family. METHODS: We herein describe an 8-year-old boy with symptoms of weakness and lethargy diagnosed with PCD through clinical evaluations, lab tests, echocardiography, and cardiac magnetic resonance imaging. The candidate variant was confirmed through whole-exome sequencing, polymerase chain reaction, and direct Sanger sequencing. The binding efficacy of normal and mutant protein-ligand complexes were evaluated via structural modeling and docking studies. RESULTS: Clinical evaluations, echocardiography, and cardiac magnetic resonance imaging findings revealed hypertrophic cardiomyopathy as a clinical presentation of PCD. Whole-exome sequencing identified a new homozygous variant, SLC22A5 (NM_003060.4), c.821G > A: p.Trp274Ter, associated with carnitine transport. Docking analysis highlighted the impact of the variant on carnitine transport, further indicating its potential role in PCD development. CONCLUSIONS: The c.821G > A: p.Trp274Ter variant in SLC22A5 potentially acted as a pathogenic factor by reducing the binding affinity of organic carnitine transporter type 2 proteins for carnitine. So, the c.821G > A variant may be associated with carnitine deficiency, metabolic abnormalities, and cardiomyopathic characteristics.

Hyperammonemia in the Pediatric Emergency Department.

ABSTRACT: Hyperammonemia is a serious clinical condition associated with significant morbidity and mortality. In the pediatric population, this is often caused by urea cycle disorders, acute liver failure, or other less common underlying etiologies. Children and teens with hyperammonemia can have a broad range of clinical findings, including vomiting, respiratory distress, and changes in mental status. As ammonia levels worsen, this presentation can progress to respiratory failure, encephalopathy, cerebral edema, seizures, and death. Given the risk of neurologic damage, timely identification and management of hyperammonemia is critical and includes initial resuscitation, early consultation with subspecialists, and initiation of appropriate therapies. It is important for pediatric emergency medicine providers to understand the clinical findings, causes, diagnosis, and management of hyperammonemia because they play a key role in the provision of effective, multidisciplinary care of these patients.

Acceptability of plasma ammonia results when samples are not transported and processed under ideal conditions.

BACKGROUND: It is recommended that samples for plasma ammonia analysis are kept chilled and processed promptly as in vitro metabolism causes falsely elevated results. Rejection of unsuitable samples can cause delayed diagnosis and treatment of hyperammonaemia with potentially serious clinical consequences. The Metabolic Biochemistry Network (MetBioNet) hyperammonaemia guideline recommends analysis of samples not collected under ideal conditions and reporting with appropriate comments. An audit found that some laboratories did not follow this guidance. An investigation was performed into whether storage at controlled room temperature and delayed sample processing affected interpretation of plasma ammonia results. METHODS: Eleven healthy volunteers provided informed consent. Blood was taken from each into 14 paediatric EDTA blood sample tubes, one placed immediately on ice, the others in a rack at room temperature. The chilled and baseline room temperature samples were centrifuged and plasma analysed by the Roche Ammonia (NH3L2) method. Samples stored at room temperature were analysed at 10-min intervals up to 2 h. RESULTS: Baseline room temperature ammonia was higher than in the chilled sample (19 ± 6.6 µmol/L [mean ± standard deviation] and 18 ± 6.6 µmol/L, respectively). Ammonia increased further by 0.09 ± 0.02 µmol/L per minute to 30 ± 8.4 µmol/L at 2 h. No result was above the reference range (50 µmol/L). No healthy subject with normal baseline ammonia would have been erroneously identified as having hyperammonaemia. CONCLUSIONS: Results support MetBioNet guidance that laboratories accept blood samples for ammonia analysis which are not processed under ideal conditions.

Screening primary carnitine deficiency in 10 million Chinese newborns: a systematic review and meta-analysis.

BACKGROUND: Primary carnitine deficiency (PCD) is a rare autosomal recessive fatty acid oxidation disorder caused by variants in SLC22A5, with its prevalence and SLC22A5 gene mutation spectrum varying across races and regions. This study aimed to systematically analyze the incidence of PCD in China and delineate regional differences in the prevalence of PCD and SLC22A5 gene variants. METHODS: PubMed, Embase, Web of Science, and Chinese databases were searched up to November 2023. Following quality assessment and data extraction, a meta-analysis was performed on screening results for PCD among Chinese newborns. RESULTS: After reviewing 1,889 articles, 22 studies involving 9,958,380 newborns and 476 PCD cases were included. Of the 476 patients with PCD, 469 underwent genetic diagnosis, revealing 890 variants of 934 alleles of SLC22A5, among which 107 different variants were detected. The meta-analysis showed that the prevalence of PCD in China was 0.05‰ [95%CI, (0.04‰, 0.06‰)] or 1/20 000 [95%CI, (1/16 667, 1/25 000)]. Subgroup analyses revealed a higher incidence in southern China [0.07‰, 95%CI, (0.05‰, 0.08‰)] than in northern China [0.02‰, 95%CI, (0.02‰, 0.03‰)] (P < 0.001). Furthermore, the result of the meta-analysis showed that the frequency of the variant with c.1400C > G, c.51C > G, c.760C > T, c.338G > A, and c.428C > T were 45% [95%CI, (34%, 59%)], 26% [95%CI, (22%, 31%)], 14% [95%CI, (10%, 20%)], 6% [95%CI, (4%, 8%)], and 5% [95%CI, (4%, 8%)], respectively. Among the subgroup analyses, the variant frequency of c.1400C > G in southern China [39%, 95%CI, (29%, 53%)] was significantly lower than that in northern China [79‰, 95%CI, (47‰, 135‰)] (P < 0.05). CONCLUSIONS: This study systematically analyzed PCD prevalence and identified common SLC22A5 gene variants in the Chinese population. The findings provide valuable epidemiological insights and guidance for future PCD screening effects in newborns.

Manejo inicial de la hiperamonemia aguda en pediatría / Initial management of acute hyperammonemia in pediatrics

La hiperamonemia constituye una emergencia médica. No existen publicaciones que hagan referencia a la disponibilidad de recursos, insumos y conocimientos necesarios para el manejo inicial de esta por parte del pediatra en nuestro país, pero, según la experiencia de los autores, los recursos necesarios no se encuentran disponibles los 365 días del año en una gran porción de nuestro territorio. Sobre la base de este estado de situación, de una revisión bibliográfica internacional sobre el tema y de la experiencia de los autores, se elaboraron una serie de recomendaciones para el manejo pediátrico inicial de esta emergencia, que tienen como objetivo poder reducir las deficiencias, permitir una sospecha clínica adecuada que lleve a un diagnóstico y tratamiento de emergencia oportunos, con utilización racional de recursos farmacológicos (algunos de ellos de alto costo), para reducir la morbimortalidad que asocia la patología.

Hyperammonemia is a medical emergency. There are no publications regarding the availability of resources, supplies, and knowledge necessary for the initial management of hyperammonemia by pediatricians in Argentina; however, according to the authors' experience, the necessary resources are not available all year round in a large portion of our territory. Based on such state of affairs, an international bibliographic review on this topic and the authors' experience, we developed a series of recommendations for the initial pediatric management of this emergency, with the objective of reducing deficiencies, allowing adequate clinical suspicion leading to a timely diagnosis and emergency management and a rational use of pharmacological resources (some of which are costly) to reduce the morbidity and mortality associated with hyperammonemia.

Analysis of blood carnitine profile and SLC22A5 gene variants in 17 neonates with Primary carnitine deficiency / 中华医学遗传学杂志

OBJECTIVE@#To analyze the blood free carnitine (C0) level and SLC22A5 gene variants in 17 neonates with Primary carnitine deficiency (PCD) and to determine its incidence in local area and explore the correlation between C0 level and genotype.@*METHODS@#148 043 newborns born in 9 counties (cities and districts) of Ningde city from September 2016 to June 2021 were selected as study subjects. Blood free carnitine and acyl carnitine of 148 043 neonates were analyzed. Variants of the SLC22A5 gene were screened in those with blood C0 < 10 µmol/L, or C0 between 10 ∼ 15 µmol/L. Correlation between the free carnitine level and genetic variants was analyzed.@*RESULTS@#In total 17 neonates were diagnosed with PCD, which yielded a prevalence of 1/8 707 in the region. Twelve variants of the SLC22A5 gene were identified, with the common ones including c.760C>T, c.1400C>G and c.51C>G. Compared with those carrying other variants of the gene, children carrying the c.760C>T variant had significantly lower C0 values (P < 0.01).@*CONCLUSION@#The prevalence of PCD is relatively high in Ningde area, and intervention measures should be taken to prevent and control the disease. The c. 760C>T variant is associated with lower level of C0, which can provide a clue for the diagnosis.

Síndrome de enterocolitis inducida por proteínas alimentarias que debuta con hiperamoniemia / Hyperammonaemia as onset of food protein-induced enterocolitis syndrome

Dentro de las alergias no mediadas por IgE, la enterocolitis inducida por proteínas alimentarias (FPIES) es el cuadro de mayor gravedad, pudiendo cursar con una clínica muy variada. El FPIES crónico se suele manifestar con letargia, palidez cutánea, desnutrición, vómitos intermitentes y/o diarrea crónica, asociados a múltiples alteraciones analíticas (leucocitosis con desviación a la izquierda, eosinofilia, anemia, trombocitosis, hipoproteinemia, hipoalbuminemia, metahemoglobinemia y acidosis metabólica). La resolución ocurre entre los 3 a 10 días tras la exclusión del alérgeno causante; vuelven a tolerarlo aproximadamente a los 3-5 años de edad. Se presenta el caso clínico de un lactante de 47 días alimentado con fórmula de inicio, que debuta con un cuadro de vómitos y diarreas con deshidratación grave, acidosis metabólica, metahemoglobinemia, hipoproteinemia, hipoalbuminemia e hiperamoniemia, siendo esta última una característica solo referenciada en un caso hasta la actualidad (AU)

Food protein-induced enterocolitis syndrome (FPIES) is the most severe non-IgE-mediated allergies, and has a broad clinical spectrum. Chronic FPIES usually manifests with lethargy, pallor, undernutrition, intermittent vomiting and/or chronic diarrhoea associated with multiple laboratory abnormalities (leucocytosis with left shift, eosinophilia, anaemia, thrombocytosis, hypoproteinaemia, hypoalbuminaemia, methemoglobinemia and metabolic acidosis). It resolves 3 to 10 days after exclusion of the causative allergen, and most patients develop tolerance to the protein again at approximately 3 to 5 years of age. We present the case of a 47-day-old infant who presented with vomiting and diarrhoea with severe dehydration, metabolic acidosis, methaemoglobinaemia, hypoproteinaemia, hypoalbuminaemia and hyperammonaemia, the latter being a feature that has only been described in one other case before. (AU)

Síndrome de depleción de ADN mitocondrial tipo 13: un caso con un inicio poco común / Mitochondrial DNA depletion syndrome-13: a case with an unusual onset

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Uso de Hemofiltración veno-venosa continua en neonatos con hiperamonemia. Serie clínica / Continuous venovenous hemofiltration in neonates with hyperammonemia. A case series

Resumen: Introducción: La hiperamonemia neonatal secundaria a errores congénitos del metabolismo es una entidad poco frecuente pero con una alta tasa de secuelas neurológicas y mortalidad. El manejo médico inicial es en muchas ocasiones insuficiente para detener el progresivo aumento de la amonemia, con el consecuente deterioro del paciente. Por esta razón se han implementado técnicas depurativas entre las que se cuenta la diálisis peritoneal, la hemodiálisis intermitente y las terapias de reemplazo renal continuo (TRRC). Objetivo: Describir nuestra experiencia en diálisis extracorpórea continua en pacientes con hiperamonemia neonatal gravemente enfermos. Pacientes y Método: Revisión retrospectiva de fichas clínicas de neonatos con hiperamonemias secundarias a errores congénitos del metabolismo sometidos a TRRC, admitidos en nuestra institución en los últimos 6 años. Se obtuvieron datos demográficos, edad cronológica y gestacional, género; datos antropométricos y de laboratorio (creatininemia, amonemia) e índice de gravedad por PIM-II. Se analizó la TRRC utilizada: modalidad, duración y complicaciones. El inicio de la terapia dependió de la respuesta al manejo médico en las primeras 24 horas, compromiso neurológico progresivo, o cifras de amonio sanguíneo elevados (> 400 μg/dl) al momento del ingreso. Las TRRC fueron realizadas con la máquina Prisma Flex, usando filtros M100 y/o HF20. Resultados: 6 neonatos, 4 varones, la mitad con antecedentes de prematurez, todos con compromiso neurológico agudo severo y amonemias en rango grave (> 1.000 μg/dl). La edad y peso promedio al iniciar la TRRC fueron de 10 días y 2.798 g respectivamente, amonemia (mediana) 1.663 μg/dl (rango 1.195-3.097). El puntaje PIM-II tuvo una mediana de 53 (rango 13,4-87,4). En promedio, los pacientes estuvieron 49,5 h en la terapia continua. En cuatro neonatos se usó una técnica dialítica mixta convectiva y difusiva (hemodiafiltración), y solo convectiva (hemofiltración) en las 2 restantes. La mortalidad fue de 33%, y uno de los sobrevivientes quedó con daño neurológico moderado permanente en seguimiento clínico. Conclusiones: Los resultados obtenidos en este grupo de neonatos extremadamente graves nos incentivan a proponer esta terapia dialítica como una excelente alternativa en el manejo de este tipo de pacientes.

Abstract: Introduction: Neonatal hyperammonemia secondary due to inborn errors of metabolism is a rare condition with a high rate of neurological sequelae and mortality. Initial medical management is often insufficient to stop the progressive increase of ammonia, with the consequent deterioration of the patient. For this reason, depurative techniques have been implemented, including peritoneal dialysis, intermittent hemodialysis and continuous renal replacement therapy (CRRT). Objective: To describe our experience with continuous extracorporeal dialysis in severely ill neonates with hyperammonemia. Patients and Methods: Retrospective review of clinical records of neonates with hyperammonemia due to congenital errors of metabolism undergoing CRRT admitted in our institution in the last 6 years. Demographic data, chronological and gestational age, gender, anthropometric and laboratory data (creatininemia, ammonemia), and severity index PIM-II where collected. It was analyzed the CRRT: modality, duration and complications. The stard of therapy depended on the response to medical management in the first 24 hours, progressive neurological involvement, or increased blood ammonia (> 400 qg/dl) at the time of admission. CRRTs were performed using the Prisma Flex system and M100 and/or HF20 filters. Results: 6 neonates, 4 males, half of them with a history of prematurity, all with severe acute neurological involvement and severe ammonemias (> 1,000 qg/dl). The average age and weight at the start of the CRRT were 10 days and 2798 g, respectively, ammonia (median) 1,663 qg/dl (range 1,195 - 3,097). The PIM-II score had a median of 53 (range 13.4 - 87.4). On average, patients were 49.5 hours in continuous therapy. In four neonates, a mixed convective and diffusive technique (hemodiafiltration) was used, and only convective one (hemofiltration) in the 2 remaining. Mortality was 33%, and one of the survivors had permanent moderate neurological damage in clinical follow-up. Conclusions: The results obtained in this extremely ill group of neonates encourage us to propose this dialytic therapy as an excellent alternative in the management of this type of patients.

Hiperamonemia en niños: clasificación y opciones terapéuticas / Hyperammonaemia in children: classification and therapeutic options

La hiperamonemia se presenta en forma secundaria por aumento en la producción de amonio, como en la hemorragia gastrointestinal o disminución de la eliminación, como ocurre en errores innatos del metabolismo, principalmente en aquellos con defectos en el ciclo de la urea, insuficiencia hepática o fármacos. Clasificar la hiperamonemia y reportar las opciones terapéuticas en niños, su abordaje clínico y revisión de la literatura. Estudio prospectivo, descriptivo y transversal de niños con hiperamonemia. Variables: edad, género, etiología, niveles de amonio, clínica, tratamiento. 21 pacientes, 12 (57,12%) varones y 9 (42,88%) hembras. Edad promedio 3,91 años (rango:<1mes-14 años). Amonio promedio general 214,66 mmol/l (rango:110-980), clasificados según severidad: sin insuficiencia hepática 11/21 con promedio de amonio 99,44 y 201 mmol/l en hiperamonemia leve y moderada respectivamente. Clínica y laboratorio de insuficiencia hepática en 10/21 con promedio de amonio de 114,44, 287,51 y 756,66 en leve, moderada y severa hiperamonemia, con una diferencia significativa entre el nivel de amonio y la presencia o ausencia de insuficiencia hepática (p<0,0001); 5/10 con insuficiencia hepática ingresaron a terapia intensiva, 4 de ellos presentaron encefalopatía hepática, un paciente fallecido. Etiología: Error innato del metabolismo 33,33%, toxicidad por medicamentos 23,80%, hepatitis viral A fulminante 19,04% y otros virus 9,52%, hepatitis autoinmune 4,76% y urosepsis 4,76%. En los casos leves-moderados se administró lactulosa dosis respuesta vía oral 19/21 y por enema rectal 7/21 con L-carnitina en 15/21 y en Hiperamonemia severa adicionalmente Benzoato de sodio en 4/21 y hubo indicación de hemodiálisis en 3 pacientes. Restricción proteica en todos, vitaminoterapia y 6 niños tratados con ácido ursodeoxicólico. La hiperamonemia es multifactorial, requiere diagnóstico temprano, la clasificación de severidad permite el tratamiento oportuno para evitar complicaciones....

Hyperammonaemia occurs secondarily by increased production of ammonia, as gastrointestinal bleeding or decreased elimination, as occurs in inborn errors of metabolism, especially in those with defects in the urea cycle, liver failure or drugs. To classify the report hyperammonaemia and therapeutic options in children, its clinical approach and review of the literature. Prospective, descriptive and transversal children with hyperammonaemia. Variables: age, gender, etiology, ammonia levels, clinical treatment. 21 patients, 12 (57,12%) males and 9 (42,88%) females. Mean age 3,91 years (range: <1m-14a). ammonium 214,66 mmol / l (range :110-980), classified according to severity: no hepatic impairment 11/21 with 99,44 average ammonium and 201 mmol / l in Hyperammoanemia mild and moderate respectively. Clinical and laboratory liver failure 10/21 with ammonium averaging 114,44, 287,51 and 756,66 as mild, moderate and severe hyperammonemia, with a significant difference between the level of ammonia and the presence or absence of liver failure (p < 0,0001), 5/10 with liver failure admitted to intensive care, 4 of them had hepatic encephalopathy, a patient died. Etiology: An inborn error of metabolism 33,33%, 23,80% drug toxicity, fulminant viral hepatitis and other viruses 19,04% 9,52% 4,76% autoimmune hepatitis and urosepsis 4,76%. In mild-moderate cases were given oral lactulose Dose 19/21 and by enema rectal 7/21 with L-carnitine in 15/21 and further severe Hyperammonemia sodium benzoate 4/21 and was indication of hemodialysis in 3 patients. Protein restriction at all, vitamin therapy and 6 children treated with ácidoursodeoxicólico. Hyperammonemia is multifactorial, requires early diagnosis, classification of severity allows early treatment to avoid complications and development of irreversible neurological sequelae

Alteración del ciclo de la urea, tratamiento de la hiperamoniemia en una Unidad de Cuidados Intensivos Pediátricos / Alteration of urea cycle, treatment of hyperammonemia in a Pediatric Intensive Care Unit

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Encefalopatía asociada a Valproato / Val proate-associated hyperammonemic encephalopathy. Report of one case

Valproate can be associated to hyperammonemic encephalopathy, characterized by fluctuating sudden-onset alterations of sensorium, focal symptoms and an increase in the frequency of seizures. We report a 78 year-old female using valproate 1,000 mg/ day for 10 months for the treatment to tonic-clonic seizures. She was admitted on three occasions in the last fourth months for self limited clouding of sensorium. Laboratory, imaging and electroencephalografic studies were non-contributory Blood ammonia levels were 123 fig/dl (normal: 15-50 fig/dl). Due to the possibility of a hyperammonemic encephalopathy secondary to valproate, the drug was discontinued and she was treated with lactulose and intravenous L-carnitine, 1 g/day The patient showed a complete recovery within 48 hours. This drug-associated encephalopathy is a reversible but potentially fatal cause, probably underdiagnosed, that requires a high index of suspicion.

Síndrome de hipoventilación tipo ROHHAD / ROHHAD type hypoventilation syndrome

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Hiperamoniemia. Tratamiento de urgencia y en fase aguda de un paciente con citrulinemia / Hyperammonaemia. Treatment in the emergency and acute phase of a patient with citrullinaemia

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Guía clínica de diagnóstico y tratamiento urgente de hiperamonemia neonatal / A guide to the clinical diagnosis and urgent treatment of neonatal hyperammonaemia

La hiperamonemia sintomática en el recién nacido es una urgencia médica que debe reconocerse de manera precoz, diagnosticarse de manera específica y tratarse de forma intensiva para mejorar el pronóstico inmediato y a largo plazo de estos niños. Para esto, es necesario que el pediatra en general y el neonatólogo en particular tengan presente una secuencia diagnostico terapéutica de actitud inmediata que contribuya a una adecuada actuación (AU)

Symptomatic hyperammonaemia in newborn is a medical emergency that should be recognised in its early stages, specifically diagnosed and aggressively treated to improve the immediate and long-term prognosis of these children. The paediatrician and the neonatal doctor should have a diagnosis-therapy scheme for its urgent management (AU)

Presentación tardía de una deficiencia de carbamilfosfato sintetasa 1 en un niño de 6 años / Late-onset presentation of carbamoyl phosphate synthetase 1 deficiency in a 6-year-old boy

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