Analysis of genotypes and biochemical phenotypes of neonates with abnormal metabolism of butyrylcarnitine / 浙江大学学报·医学版

OBJECTIVES@#To investigate the genotypes and biochemical phenotypes of neonates with abnormal metabolism of butyrylcarnitine (C4).@*METHODS@#One hundred and twenty neonates with increased C4 levels detected by tandem mass spectrometry in the neonatal screening at Children's Hospital, Zhejiang University School of Medicine from January 2018 to June 2023 were included. The initial screening data and recalled data of C4 and C4/C3 were collected and converted into multiples of C4 reference range. Next generation sequencing was performed and the exons with adjacent 50 bp regions of ACAD8 and ACADS genes were captured by liquid phase capture technique. Variant information was obtained by bioinformatic analysis and the pathogenicity were classified according to the American College of Medical Genetics and Genomics criteria. The Wilcoxon rank sum test was used to analyze the differences in C4 levels among neonates with different variation types.@*RESULTS@#In total, 32 variants in ACAD8 gene were detected, of which 7 variants were reported for the first time; while 41 variants of ACADS gene were detected, of which 17 variants have not been previously reported. There were 39 cases with ACAD8 biallelic variations and 3 cases with ACAD8 monoallelic variations; 34 cases with ACADS biallelic variations and 36 cases with ACADS monoallelic variations. Furthermore, 5 cases were detected with both ACAD8 and ACADS gene variations. Inter group comparison showed that the multiples of C4 reference range in initial screening and re-examination of the ACAD8 biallelic variations and ACADS biallelic variations groups were significantly higher than those of the ACADS monoallelic variations group (all P<0.01), while the multiples in the ACAD8 biallelic variations group were significantly higher than those in the ACADS biallelic variations group (all P<0.01). The multiples of C4 reference range in the initial screening greater than 1.5 times were observed in all neonates carrying ACAD8 or ACADS biallelic variations, while only 25% (9/36) in neonates carrying ACADS monoallelic variations.@*CONCLUSIONS@#ACAD8 and/or ACADS gene variants are the main genetic causes for elevated C4 in newborns in Zhejiang region with high genotypic heterogeneity. The C4 levels of neonates with biallelic variations are significantly higher than those of neonates with monoallelic variations. The cut-off value for C4 level could be modestly elevated, which could reduce the false positive rate in tandem mass spectrometry neonatal screening.

Carnitine analysis in pterygium / Análise de carnitina no pterígio

ABSTRACT Purpose: The aim of the present study was to measure the free carnitine and acylcarnitine levels in pterygium tissue and normal conjunctival tissue at the metabolomics level using tandem mass spectrometry. Methods: In this prospective, clinical randomized study, pterygium tissues and normal conjunctival tissues taken during pterygium excision with autograft were compared regarding their free carnitine and acylcarnitine profiles. After tissue homogenization, carnitine levels were measured using tandem mass spectrometry. The data were statistically analyzed with the Wilcoxon signed-rank test. Results: Pterygium and normal conjunctival tissue samples from a single eye of 29 patients (16 females, 13 males; mean age, 54.75 ± 11.25 years [range, 21-78 years]) were evaluated. While the free carnitine (C0) level was significantly high in the pterygium tissue (p<0.001), acylcarnitine levels were significantly high in some esterized derivatives (C2, C5, C5:1, C5DC, C16:1, C18, methylglutarylcarnitine) (p<0.05). No statistically significant difference was determined for the other esterized derivatives (p>0.05). Conclusion: That the carnitine levels in pterygium tissue were higher suggests that acceleration of cell metabolism developed secondary to chronic inflammation and the premalignant characteristics of pterygium tissue. High carnitine levels may also effectively suppress the apoptosis process. The data reported in our study indicate that further, more extensive studies of the carnitine profile could help clarify the pathogenesis of pterygium.

RESUMO Objetivo: O objetivo deste estudo foi medir os níveis de carnitina livre e acil-carnitina a nível metabolómico com espectrometria de massa em tandem no tecido do pterígio e no tecido conjuntivo normal. Método: Neste estudo prospetivo, clínico e aleatório, os tecidos de pterígio e os tecidos normais de conjuntiva, retirados durante a cirurgia de pterígio com autoenxerto, foram comparados em relação ao perfil de carnitina livre e de acil-carnitina. Após a homogeneização dos tecidos, os níveis de carnitina foram medidos por espectrometria de massa em tandem. A análise estatística dos dados foi realizada com o teste dos postos sinalizados de Wilcoxon. Resultados: A avaliação foi feita através de amostras de tecido pterígio e de conjuntiva normal de um único olho de 29 pacientes (16 mulheres, 13 homens). A média de idade dos pacientes foi de 54,75 ± 11,25 anos (faixa dos 21 aos 78 anos). Enquanto o nível de carnitina livre (C0) foi significativamente elevado no tecido pterígio (p<0,001), os níveis de acil-carnitina foram significativamente elevados em alguns derivados esterificados (C2, C5, C5: 1, C5DC, C16:1, C18, metilglutaril carnitina) (p<0,05). Não foi determinada uma diferença estatisticamen te significante noutros derivados esterificados (p>0,05). Conclusão: Os níveis mais elevados de carnitina no tecido do pterígio sugerem que a aceleração do metabolismo celular se tenha tornado secundária com o efeito da inflamação crónica e o caráter pré-maligno do tecido do pterígio. Os níveis elevados de carnitina também podem ser eficazes na supressão do processo de apoptose. Os dados obtidos no estudo indicam que estudos mais extensivos do perfil da carnitina contribuiriam para o esclarecimento da patogénese do pterígio.

Diagnóstico in vitro de la deficiencia primaria de carnitina / In vitro diagnosis of primary carnitine deficiency

El transportador de carnitina (OCTN2) es fundamental para el metabolismo mitocondrial de los ácidos grasos de cadena larga. Su carencia produce la deficiencia primaria de carnitina. El presente estudio tuvo como objetivo el análisis de los ácidos grasos producidos por fibroblastos incubados en presencia de sustratos deuterados, mediante cromatografía de gases acoplada a espectrometría de masas (GC - MS) como herramienta diagnóstica de la deficiencia primaria de carnitina. Se encontró un perfil característico en esta deficiencia, lo que permite su diagnóstico in vitro.

Carnitine transporter (OCTN2) is required for the mitochondrial metabolism of long-chain fatty acids. Primary carnitine deficiency is a consequence of its deficiency. The objective of the present study was to analyse the fatty acids produced by fibroblasts incubated with deuterated substrates, using gas chromatography-mass spectrometry as a diagnostic tool for the diagnosis of VLCAD deficiency. A characteristic profile for this deficiency was found using this technique which enables its in vitro diagnosis.

L-carnitina y el desarrollo pondoestatural en recién nacidos pretérminos acordes a edad gestacional / L-carnitina and the development pondostatural in newborn preterm in agreement to gestational age

Se seleccionó una muestra de 40 recién nacidos pretérminos acordes para la edad gestacional sin ningún tipo de enfermedad o trastorno, hijos de embarazadas con gestación entre 34 y 36 semanas; de los cuales 17 constituyeron la muestra definitiva para el estudio y que fueron subclasificados por azar simple en grupo estudio (n=9) que recibió L-carnitina oral y grupo control (n=7) que recibió placebo. Se hizo estudio comparativo, doble ciego, longitudinal con el objetivo de avaluar la carnitinemia libre al nacer y al mes de edad, así como el peso corporal y la talla, independientemente del sexo y otras características de persona. Se demostró hipocarnitinemia al nacer (20 uMol/lt), lo que contrasta con el valor de la población normal (40 uMol/lt), así como diferencia significativa en el aumento de las medidas del peso corporal y de la talla de los que recibieron L-carnitina con respecto al grupo control o placebo (to<0.05). Estos resultados demuestran que la deficiencia de L-carnitina en el pretérmino, influye en el menor desarrollo pondoestatural y permite recomendar su uso sistemático en todo niño pretérmino. Otra utilidad de la presente investigación, fué la obtención de los valores normales de carnitina libre en plasma en pretérminos de la Maternidad Concepción Palacios y pueden servir de referencia para otros trabajos de investigación

Carnitine and lipid metabolism

Carnitine, a short-chain nitrogen containing carboxylic acid, is found in meat and dairy foods. Carnitine aids in a shuttle process that makes long-chain, fatty-acid coenzyme A derivatives available for B-oxidation. Normal healthy adults have adequate carmitine stores and do not require dietary carnitine. However, neonates, chronically and critically ill patients with decreased muscle and liver carnitine store seen to benefit from carnitine supplementation to enhance their tolerance of metabolic stress