RESUMO
BACKGROUND: Propionate inborn errors of metabolism (PIEM), including propionic (PA) and methylmalonic (MMA) acidemias, are inherited metabolic diseases characterized by toxic accumulation of propionic, 3-hydroxypropionic, methylcitric, and methylmalonic organic acids in biological fluids, causing recurrent acute metabolic acidosis events and encephalopathy, which can lead to fatal outcomes if managed inadequately. PIEM patients can develop hematological abnormalities and immunodeficiency, either as part of the initial clinical presentation or as chronic complications. The origin and characteristics of these abnormalities have been studied poorly. Thus, the aim of the present work was to evaluate and describe lymphoid, myeloid, and erythroid cell population profiles in a group of clinically stable PIEM patients. METHODS: This was a retrospective study of 11 nonrelated Mexican PIEM patients. Clinical, biochemical, nutritional, hematological, and lymphocyte subsets were analyzed. RESULTS: Despite being considered clinically stable, 91% of patients had hematological or immunological abnormalities. The absolute lymphocyte subset counts were low in all patients but one, with CD4+ T-cell lymphopenia, being the most common one. Furthermore, of the 11 studied subjects, nine presented with a low CD4/CD8 ratio. Among the observed hematological alterations, bicytopenia was the most common (82%) one, followed by anemia (27%). CONCLUSION: Our results contribute to the landscape of immunological abnormalities observed previously in PIEM patients; these abnormalities can become a life-threatening chronic complications because of the increased risk of opportunistic diseases. These findings allow us to propose the inclusion of monitoring immune biomarkers, such as subsets of lymphocytes in the follow up of PIEM patients.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Linfócitos B/patologia , Subpopulações de Linfócitos/patologia , Linfócitos T/patologia , Erros Inatos do Metabolismo dos Aminoácidos/imunologia , Antígenos de Diferenciação/metabolismo , Linfócitos B/metabolismo , Biomarcadores/sangue , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Subpopulações de Linfócitos/metabolismo , Masculino , Acidemia Propiônica/sangue , Acidemia Propiônica/imunologia , Estudos Retrospectivos , Linfócitos T/metabolismoRESUMO
Propionic acidemia (PA) is caused by inherited deficiency of mitochondrial propionyl-CoA carboxylase (PCC) and results in significant neurodevelopmental and cardiac morbidity. However, relationships among therapeutic intervention, biochemical markers, and disease progression are poorly understood. Sixteen individuals homozygous for PCCB c.1606A > G (p.Asn536Asp) variant PA participated in a two-week suspension of therapy. Standard metabolic markers (plasma amino acids, blood spot methylcitrate, plasma/urine acylcarnitines, urine organic acids) were obtained before and after stopping treatment. These same markers were obtained in sixteen unaffected siblings. Echocardiography and electrocardiography were obtained from all subjects. We characterized the baseline biochemical phenotype of untreated PCCB c.1606A > G homozygotes and impact of treatment on PCC deficiency biomarkers. Therapeutic regimens varied widely. Suspension of therapy did not significantly alter branched chain amino acid levels, their alpha-ketoacid derivatives, or urine ketones. Carnitine supplementation significantly increased urine propionylcarnitine and its ratio to total carnitine. Methylcitrate blood spot and urine levels did not correlate with other biochemical measures or cardiac outcomes. Treatment of PCCB c.1606A > G homozygotes with protein restriction, prescription formula, and/or various dietary supplements has a limited effect on core biomarkers of PCC deficiency. These patients require further longitudinal study with standardized approaches to better understand the relationship between biomarkers and disease burden.
Assuntos
Carbono-Carbono Ligases/genética , Coração/fisiopatologia , Transtornos do Neurodesenvolvimento/genética , Acidemia Propiônica/genética , Ácidos/sangue , Ácidos/urina , Adolescente , Adulto , Aminoácidos/sangue , Aminoácidos/urina , Biomarcadores/sangue , Biomarcadores/urina , Carbono-Carbono Ligases/sangue , Carbono-Carbono Ligases/urina , Carnitina/sangue , Carnitina/urina , Criança , Pré-Escolar , Ecocardiografia , Feminino , Coração/diagnóstico por imagem , Humanos , Masculino , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mutação/genética , Transtornos do Neurodesenvolvimento/sangue , Transtornos do Neurodesenvolvimento/diagnóstico por imagem , Transtornos do Neurodesenvolvimento/urina , Compostos Orgânicos/sangue , Compostos Orgânicos/urina , Fenótipo , Acidemia Propiônica/sangue , Acidemia Propiônica/diagnóstico por imagem , Acidemia Propiônica/urina , Adulto JovemRESUMO
Methylcitric acid (MCA) analysis has been mainly utilized for the diagnosis of propionate disorders or as a second-tier test in newborn screening, but its utility for patients monitoring still needs to be established. We explored the potential contribution of MCA in the long-term management of organic acidurias. We prospectively evaluated plasma MCA and its relationship with disease biomarkers, clinical status, and disease burden in 22 patients, 13 with propionic acidemia (PA) and nine with methylmalonic acidemia (MMA) on standard treatment and/or after transplantation. Samples were collected at scheduled routine controls or during episodes of metabolic decompensation (MD), 10 patients were evaluated after transplantation (six liver, two combined liver and kidney, 2 kidney). MCA levels were higher in PA compared to MMA and its levels were not influenced by the clinical status (MD vs well state). In MMA, MCA was higher in elder patients and, along with fibroblast growth factor 21 (FGF21) and plasma methylmalonic acid, negatively correlated with GFR. In both diseases, MCA correlated with ammonia, glycine, lysine, C3, and the C3/C2, C3/C16 ratios. The disease burden showed a direct correlation with MCA and FGF21, for both diseases. All transplanted patients showed a significant reduction of MCA in comparison to baseline values, with some differences dependent on the type of transplantation. Our study provided new insights in understanding the disease pathophysiology, showing similarities between MCA and FGF21 in predicting disease burden, long-term complications and in evaluating the impact of organ transplantation.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Citratos/sangue , Fatores de Crescimento de Fibroblastos/sangue , Acidemia Propiônica/sangue , Adolescente , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico , Biomarcadores/sangue , Criança , Pré-Escolar , Feminino , Seguimentos , Humanos , Lactente , Masculino , Ácido Metilmalônico/sangue , Transplante de Órgãos , Valor Preditivo dos Testes , Acidemia Propiônica/diagnóstico , Adulto JovemRESUMO
Classical organic acidemias (OAs) result from defective mitochondrial catabolism of branched-chain amino acids (BCAAs). Abnormal mitochondrial function relates to oxidative stress, ectopic lipids and insulin resistance (IR). We investigated whether genetically impaired function of mitochondrial BCAA catabolism associates with cardiometabolic risk factors, altered liver and muscle energy metabolism, and IR. In this case-control study, 31 children and young adults with propionic acidemia (PA), methylmalonic acidemia (MMA) or isovaleric acidemia (IVA) were compared with 30 healthy young humans using comprehensive metabolic phenotyping including in vivo 31 P/1 H magnetic resonance spectroscopy of liver and skeletal muscle. Among all OAs, patients with PA exhibited abdominal adiposity, IR, fasting hyperglycaemia and hypertriglyceridemia as well as increased liver fat accumulation, despite dietary energy intake within recommendations for age and sex. In contrast, patients with MMA more frequently featured higher energy intake than recommended and had a different phenotype including hepatomegaly and mildly lower skeletal muscle ATP content. In skeletal muscle of patients with PA, slightly lower inorganic phosphate levels were found. However, hepatic ATP and inorganic phosphate concentrations were not different between all OA patients and controls. In patients with IVA, no abnormalities were detected. Impaired BCAA catabolism in PA, but not in MMA or IVA, was associated with a previously unrecognised, metabolic syndrome-like phenotype with abdominal adiposity potentially resulting from ectopic lipid storage. These findings suggest the need for early cardiometabolic risk factor screening in PA.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Aminoácidos de Cadeia Ramificada/deficiência , Aminoácidos de Cadeia Ramificada/metabolismo , Isovaleril-CoA Desidrogenase/deficiência , Acidemia Propiônica/sangue , Adolescente , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico , Distribuição da Gordura Corporal , Fatores de Risco Cardiometabólico , Estudos de Casos e Controles , Criança , Análise por Conglomerados , Metabolismo Energético , Feminino , Humanos , Resistência à Insulina , Isovaleril-CoA Desidrogenase/sangue , Fígado/metabolismo , Espectroscopia de Ressonância Magnética , Masculino , Músculo Esquelético/metabolismo , Acidemia Propiônica/diagnóstico , Adulto JovemRESUMO
Propionic acidemia (PA) and methylmalonic acidemia (MMA) comprise the most common organic acidemias and account for profound morbidity in affected individuals. Although liver transplantation (LT) has emerged as a bulk enzyme-replacement strategy to stabilize metabolically fragile patients, it is not a metabolic cure because patients remain at risk for disease-related complications. We retrospectively studied LT and/or liver-kidney transplant in 9 patients with PA or MMA with additional focus on the optimization of metabolic control and management in the perioperative period. Metabolic crises were common before transplant. By implementing a strategy of carbohydrate minimization with gradual but early lipid and protein introduction, lactate levels significantly improved over the perioperative period (P < 0.001). Posttransplant metabolic improvement is demonstrated by improvements in serum glycine levels (for PA; P < 0.001 × 10-14 ), methylmalonic acid levels (for MMA; P < 0.001), and ammonia levels (for PA and MMA; P < 0.001). Dietary restriction remained after transplant. However, no further metabolic crises have occurred. Other disease-specific comorbidities such as renal dysfunction and cardiomyopathy stabilized and improved. In conclusion, transplant can provide a strategy for altering the natural history of PA and MMA providing stability to a rare but metabolically brittle population. Nutritional management is critical to optimize patient outcomes.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/cirurgia , Transplante de Fígado , Assistência Perioperatória/métodos , Acidemia Propiônica/cirurgia , Erros Inatos do Metabolismo dos Aminoácidos/sangue , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico , Biomarcadores/sangue , Bases de Dados Factuais , Metabolismo Energético , Nutrição Enteral , Feminino , Gastrostomia , Sobrevivência de Enxerto , Humanos , Recém-Nascido , Transplante de Rim , Transplante de Fígado/efeitos adversos , Masculino , Estado Nutricional , Assistência Perioperatória/efeitos adversos , Complicações Pós-Operatórias/terapia , Acidemia Propiônica/sangue , Acidemia Propiônica/diagnóstico , Recuperação de Função Fisiológica , Estudos Retrospectivos , Fatores de Tempo , Resultado do TratamentoRESUMO
PURPOSE OF REVIEW: The current review highlights the varied effects of medical foods high in leucine (Leu) and devoid of valine (Val) and isoleucine (Ile) in the management of methylmalonic acidemia (MMA) and propionic acidemia and cobalamin C (cblC) deficiency, aiming to advance dietary practices. RECENT FINDINGS: Leu is a key metabolic regulator with a multitude of effects on different organ systems. Recent observational studies have demonstrated that these effects can have unintended consequences in patients with MMA as a result of liberal use of medical foods. The combination of protein restriction and medical food use in MMA and propionic acidemia results in an imbalanced branched-chain amino acid (BCAA) dietary content with a high Leu-to-Val and/or Ile ratio. This leads to decreased plasma levels of Val and Ile and predicts impaired brain uptake of multiple essential amino acids. Decreased transport of methionine (Met) across the blood-brain barrier due to high circulating Leu levels is of particular concern in cblC deficiency in which endogenous Met synthesis is impaired. SUMMARY: Investigations into the optimal composition of medical foods for MMA and propionic acidemia, and potential scenarios in which Leu supplementation may be beneficial are needed. Until then, MMA/propionic acidemia medical foods should be used judiciously in the dietary management of these patients and avoided altogether in cblC deficiency.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/dietoterapia , Dieta com Restrição de Proteínas , Alimentos Especializados , Leucina/uso terapêutico , Acidemia Propiônica/dietoterapia , Erros Inatos do Metabolismo dos Aminoácidos/sangue , Animais , Deficiências Nutricionais/sangue , Deficiências Nutricionais/etiologia , Deficiências Nutricionais/prevenção & controle , Dieta com Restrição de Proteínas/efeitos adversos , Alimentos Especializados/efeitos adversos , Homocistinúria/sangue , Homocistinúria/dietoterapia , Humanos , Isoleucina/sangue , Isoleucina/deficiência , Leucina/efeitos adversos , Acidemia Propiônica/sangue , Valina/sangue , Valina/deficiência , Deficiência de Vitamina B 12/sangue , Deficiência de Vitamina B 12/congênito , Deficiência de Vitamina B 12/dietoterapiaRESUMO
BACKGROUND: Recurrent acute and life-threatening metabolic decompensations are thought to be the major cause of mortality and morbidity in patients with propionic acidemia (PA). Since metabolic decompensations in these patients usually develop gradually, there is considerable uncertainty about the beginning and when emergency treatment should be initiated. The major aim of this study was to evaluate the usefulness of biochemical parameters for improving decision-making on the start of emergency treatment. METHODS: We analysed data of 16 PA patients continuously followed in our centre. Metabolic decompensation was defined clinically by the occurrence of at least one of three alarming symptoms: vomiting, food refusal or impaired consciousness. Thirty-eight biochemical parameters were analysed. RESULTS: A total of 259 metabolic decompensations were documented and compared with 625 routine visits. Among the symptoms used to clinically define metabolic decompensations, vomiting was most frequent (87 %). In total, 19 biochemical parameters differentiated between metabolic decompensations and routine visits. Among them ammonia, acid-base balance and anion gap were most reliable to identify a metabolic decompensation, and to estimate its severity. A comparative analysis of patients with PA and methylmalonic acidemia during metabolic decompensation showed similar results. CONCLUSIONS: Ammonia, acid-base balance and anion gap are important biochemical parameters to identify an (impending) metabolic decompensation and to assess its severity in PA patients. The identified biochemical parameters should be integrated in an algorithm for clinical decision-making on emergency treatment and should be tested in a prospective trial.
Assuntos
Tomada de Decisões , Tratamento de Emergência , Acidemia Propiônica/sangue , Acidemia Propiônica/terapia , Equilíbrio Ácido-Base , Adolescente , Adulto , Erros Inatos do Metabolismo dos Aminoácidos/sangue , Amônia/química , Apetite , Criança , Pré-Escolar , Técnicas de Apoio para a Decisão , Humanos , Propionatos/química , Acidemia Propiônica/diagnóstico , Inconsciência , Vômito , Adulto JovemRESUMO
AIM: To study whether patients with organic acidaemias have altered glutathione (GSH) levels and thiol redox status. Previously, organic acidaemias have been associated with mitochondrial dysfunction and oxidative stress, suggesting an increased need for antioxidant protection. Furthermore, dietary protein restriction may impair GSH synthesis in these diseases. METHODS: In children with organic acidaemias, cysteine (CYSH) and GSH concentrations in plasma and erythrocytes as well as erythrocyte GSH peroxidase, GSH reductase, GSH S-transferase and glucose-6-phosphate dehydrogenase activities were studied. In addition, GSH and CYSH concentrations were measured in human fibroblasts exposed to organic acids. RESULTS: Patients with organic acidaemias had lower plasma GSH concentration than their controls. A greater fraction of GSH and CYSH in the patients' plasma was oxidized, suggesting decreased GSH synthesis and increased consumption. CONCLUSION: Patients with organic acidaemias may have a relative GSH deficiency. With further research, these results could also have therapeutic implications.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Cisteína/metabolismo , Glutationa/metabolismo , Adolescente , Erros Inatos do Metabolismo dos Aminoácidos/metabolismo , Biomarcadores/sangue , Estudos de Casos e Controles , Células Cultivadas , Criança , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Cisteína/sangue , Fibroblastos/metabolismo , Glucosefosfato Desidrogenase/sangue , Glutationa/sangue , Glutationa/deficiência , Glutationa Peroxidase/sangue , Glutationa Redutase/sangue , Glutationa Transferase/sangue , Humanos , Lactente , Isovaleril-CoA Desidrogenase/sangue , Isovaleril-CoA Desidrogenase/deficiência , Estresse Oxidativo , Acidemia Propiônica/sangueRESUMO
Hemophagocytic lymphohistiocytosis (HLH) may develop secondary to infections, malignancies, immune deficiency syndromes, and rheumatologic and metabolic disorders. Associations between HLH and inborn errors of metabolism, including lysinuric protein intolerance, multiple sulfatase deficiency, galactosemia, Gaucher disease, Pearson syndrome, and galactosialidosis, have previously been reported in the literature. In this report the authors present 3 children with disorders of propionate metabolism--1 with methylmalonic acidemia and 2 with propionic acidemia--who developed secondary HLH during their metabolic attacks. All patients fulfilled the 5 HLH criteria of the Histiocyte Society. Familial HLH was ruled out by molecular analysis. Plasma exchange was performed for 2 of them. Unfortunately 1 died of multiorgan failure despite intensive therapy. This is the first report of such an association.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos , Linfo-Histiocitose Hemofagocítica , Acidemia Propiônica , Erros Inatos do Metabolismo dos Aminoácidos/sangue , Erros Inatos do Metabolismo dos Aminoácidos/complicações , Erros Inatos do Metabolismo dos Aminoácidos/terapia , Criança , Pré-Escolar , Feminino , Humanos , Linfo-Histiocitose Hemofagocítica/sangue , Linfo-Histiocitose Hemofagocítica/etiologia , Linfo-Histiocitose Hemofagocítica/terapia , Masculino , Troca Plasmática , Acidemia Propiônica/sangue , Acidemia Propiônica/complicações , Acidemia Propiônica/terapiaRESUMO
ABSTRACT: Propionic acidemia is associated with pathogenic variants in PCCA or PCCB gene. We investigated the potential pathogenic variants in PCCA or PCCB genes in Fujian Han population.Two probands and their families of Han ethnicity containing two generations were subject to newborn screening using tandem mass spectrometry, followed by diagnosis using urine gas chromatography mass spectrometry. Sanger sequencing was used to identify potential mutations in PCCA and PCCB genes.Compound heterozygous variants were identified in PCCB gene in two siblings of the first family, the youngest girl showed a novel missense variant c.1381G>C (p.Ala461Pro) in exon 13 and a heterozygous missense variant c.1301C>T (p.Ala434Val) in exon 13, which were inherited respectively from their parents. The oldest boy is a carrier with a novel missense variant c.1381G>C (p.Ala461Pro) in exon 13 which were inherited from his father. In the second family, c.1535G>A homozygous mutations were identified in the baby girl, which were inherited respectively from their parents. In silico analysis, several different types of bioinformatic software were utilized, which predicted that the novel variant c.1381G>C in PCCB gene was damaged. According to ACMG principle, the missense variant c.1381G>C (p.Ala461Pro) in exon 13 was a Variant of Undetermined Significance (VUS).One novel missense variant and two missense variants in PCCB gene were identified in the study. The novel variant of PCCB gene identified VUS was identified for the first time in the Chinese population, which enriched the mutational spectrum of PCCB gene.
Assuntos
Carbono-Carbono Ligases/genética , Metilmalonil-CoA Descarboxilase/genética , Acidemia Propiônica/genética , Povo Asiático/genética , Análise Mutacional de DNA , Feminino , Testes Genéticos , Heterozigoto , Humanos , Lactente , Recém-Nascido , Mutação de Sentido Incorreto , Triagem Neonatal , Linhagem , Acidemia Propiônica/sangue , Acidemia Propiônica/diagnóstico , Espectrometria de Massas em TandemRESUMO
The objective of the study is to analyze plasma amino acid concentrations in propionic acidemia (PA) for the purpose of elucidating possible correlations between propionyl-CoA carboxylase deficiency and distinct amino acid behavior. Plasma concentrations of 19 amino acids were measured in 240 random samples from 11 patients (6 families) with enzymatically and/or genetically proven propionic acidemia (sampling period, January 2001-December 2007). They were compared with reference values from the literature and correlated with age using the Pearson correlation coefficient test. Decreased plasma concentrations were observed for glutamine, histidine, threonine, valine, isoleucine, leucine, phenylalanine and arginine. Levels of glycine, alanine and aspartate were elevated, while values of serine, asparagine, ornithine and glutamate were normal. For lysine, proline and methionine a clear association was not possible. Significant correlations with age were observed for 13 amino acids (positive correlation: asparagine, glutamine, proline, alanine, histidine, threonine, methionine, arginine; negative correlation: leucine, phenylalanine, ornithine, glutamate and aspartate). This study gives new insight over long-term changes in plasma amino acid concentrations and may provide options for future therapies (e.g., substitution of anaplerotic substances) in PA patients.
Assuntos
Envelhecimento/sangue , Aminoácidos/sangue , Acidemia Propiônica/sangue , Adolescente , Adulto , Criança , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Lactente , MasculinoRESUMO
Hyperammonaemia is common in neonates with branched-chain organic acidaemias, primarily due to the inhibition of N-acetylglutamate (NAG) synthetase; NAG is an activator for carbamylphosphate synthetase I, the first enzyme of the urea cycle. N-Carbamylglutamate, a NAG analogue, has been reported to correct hyperammonaemia in neonates with organic acidaemias. It is, however, uncertain how the ammonia concentrations in these neonates would have progressed without the drug. We report a neonate with propionic acidaemia, whose plasma ammonia concentration responded dramatically to N-carbamylglutamate, having previously been over 950 µmol/L for 33 h. Our patient presented with poor feeding, hypoglycaemia, acidosis and hyperammonaemia (1044 µmol/L at 65 h of age). The patient was treated with intravenous glucose (12 mg/kg per min), insulin, sodium benzoate, sodium phenylbutyrate, carnitine and continuous veno-venous haemofiltration (CVVH). In spite of these measures, the plasma ammonia concentration remained above 950 µmol/L. After 30 h of CVVH, N-carbamylglutamate (250 mg/kg) was given through a nasogastric tube. Over the following 4 h, the plasma ammonia fell from 1410 µmol/L to 267 µmol/L. Despite stopping CVVH, the ammonia level dropped to 137 µmol/L over the next 2 h and it continued to fall while the intravenous drug doses were reduced. The patient was readmitted, aged 4 weeks, with hyperammonaemia (347 µmol/L) and again this responded to N-carbamylglutamate. In contrast, we report a previous patient with propionic acidaemia who showed no response to a lower dose of N-carbamylglutamate (25 mg/kg).
Assuntos
Amônia/sangue , Glutamatos/administração & dosagem , Hiperamonemia/tratamento farmacológico , Acidemia Propiônica/complicações , Biomarcadores/sangue , Feminino , Humanos , Hiperamonemia/sangue , Hiperamonemia/etiologia , Recém-Nascido , Intubação Gastrointestinal , Masculino , Acidemia Propiônica/sangue , Acidemia Propiônica/terapia , Fatores de Tempo , Resultado do TratamentoRESUMO
Propionic acidemia (PA) is an inherited metabolic disease caused by low activity of propionyl coenzyme A (CoA) carboxylase (PCC), which metabolizes propionyl-CoA into methylmalonyl-CoA. Although many patients with PA have been identified by tandem mass spectrometry since the test was first included in neonatal mass screening in the 1990s, the disease severity varies. Thus, determining the specific level of PCC activity is considered to be helpful to grasp the severity of PA. We developed a new PCC assay method by the determination of methylmalonyl-CoA, which is formed by an enzyme reaction using peripheral lymphocytes, based on ultra high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). With methylmalonyl-CoA concentrations of 0.05, 0.5, and 5µmol/L, the intra-assay coefficients of variation (CVs) were 8.2%, 8.7%, and 5.1%, respectively, and the inter-assay CVs were 13.6%, 10.5%, and 5.9%, respectively. The PCC activities of 20 healthy individuals and 6 PA patients were investigated with this assay. Methylmalonyl-CoA was not detected in one PA patient with a severe form of the disease, but the remaining PA patients with mild disease showed residual activities (3.3-7.8%). These results demonstrate that determination of PCC activity with this assay would be useful to distinguish between mild and severe cases of PA to help choose an appropriate treatment plan.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Metilmalonil-CoA Descarboxilase/sangue , Metilmalonil-CoA Descarboxilase/metabolismo , Acidemia Propiônica/enzimologia , Espectrometria de Massas em Tandem/métodos , Adulto , Estudos de Casos e Controles , Criança , Feminino , Humanos , Lactente , Recém-Nascido , Limite de Detecção , Modelos Lineares , Masculino , Acidemia Propiônica/sangue , Reprodutibilidade dos Testes , Adulto JovemRESUMO
BACKGROUND AND AIMS: Increased propionylcarnitine levels in newborn screening are indicative for a group of potentially severe disorders including propionic acidemia (PA), methylmalonic acidemias and combined remethylation disorders (MMACBL). This alteration is relatively non-specific, resulting in the necessity of confirmation and differential diagnosis in subsequent tests. Thus, we aimed to develop a multiplex approach for concurrent determination of 3-hydroxypropionic acid, methylmalonic acid and methylcitric acid from the same dried blood spot (DBS) as in primary screening (second-tier test). We also set out to validate the method using newborn and follow-up samples of patients with confirmed PA or MMACBL. METHODS: The assay was developed using liquid chromatography-tandem mass spectrometry and clinically validated with retrospective analysis of DBS samples from PA or MMACBL patients. RESULTS: Reliable determination of all three analytes in DBSs was achieved following simple and fast (<20 min) sample preparation without laborious derivatization or any additional pipetting steps. The method clearly distinguished the pathological and normal samples and differentiated between PA and MMACBL in all stored newborn specimens. Methylcitric acid was elevated in all PA samples; 3-hydroxypropionic acid was also high in most cases. Methylmalonic acid was increased in all MMACBL specimens; mostly together with methylcitric acid. CONCLUSIONS: A liquid chromatography-tandem mass spectrometry assay allowing simultaneous determination of the biomarkers 3-hydroxypropionic acid, methylmalonic acid and methylcitric acid in DBSs has been developed. The assay can use the same specimen as in primary screening (second-tier test) which may reduce the need for repeated blood sampling. The presented preliminary findings suggest that this method can reliably differentiate patients with PA and MMACBL in newborn screening. The validated assay is being evaluated prospectively in a pilot project for extension of the German newborn screening panel (?Newborn screening 2020"; Newborn Screening Center, University Hospital Heidelberg).
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Citratos/sangue , Teste em Amostras de Sangue Seco/métodos , Ácido Láctico/análogos & derivados , Programas de Rastreamento/métodos , Ácido Metilmalônico/sangue , Acidemia Propiônica/sangue , Cromatografia Líquida/métodos , Feminino , Humanos , Recém-Nascido , Ácido Láctico/sangue , Masculino , Espectrometria de Massas/métodosRESUMO
BACKGROUND: Isovaleric aciduria (IVA), propionic aciduria (PA) and methylmalonic aciduria (MMA) are inherited organic acidurias (OAs) in which impaired organic acid metabolism induces hyperammonaemia arising partly from secondary deficiency of N-acetylglutamate (NAG) synthase. Rapid reduction in plasma ammonia is required to prevent neurological complications. This retrospective, multicentre, open-label, uncontrolled, phase IIIb study evaluated the efficacy and safety of carglumic acid, a synthetic structural analogue of NAG, for treating hyperammonaemia during OA decompensation. METHODS: Eligible patients had confirmed OA and hyperammonaemia (plasma NH3 > 60 µmol/L) in ≥1 decompensation episode treated with carglumic acid (dose discretionary, mean (SD) first dose 96.3 (73.8) mg/kg). The primary outcome was change in plasma ammonia from baseline to endpoint (last available ammonia measurement at ≤18 hours after the last carglumic acid administration, or on Day 15) for each episode. Secondary outcomes included clinical response and safety. RESULTS: The efficacy population (received ≥1 dose of study drug and had post-baseline measurements) comprised 41 patients (MMA: 21, PA: 16, IVA: 4) with 48 decompensation episodes (MMA: 25, PA: 19, IVA: 4). Mean baseline plasma ammonia concentration was 468.3 (±365.3) µmol/L in neonates (29 episodes) and 171.3 (±75.7) µmol/L in non-neonates (19 episodes). At endpoint the mean plasma NH3 concentration was 60.7 (±36.5) µmol/L in neonates and 55.2 (±21.8) µmol/L in non-neonates. Median time to normalise ammonaemia was 38.4 hours in neonates vs 28.3 hours in non-neonates and was similar between OA subgroups (MMA: 37.5 hours, PA: 36.0 hours, IVA: 40.5 hours). Median time to ammonia normalisation was 1.5 and 1.6 days in patients receiving and not receiving concomitant scavenger therapy, respectively. Although patients receiving carglumic acid with scavengers had a greater reduction in plasma ammonia, the endpoint ammonia levels were similar with or without scavenger therapy. Clinical symptoms improved with therapy. Twenty-five of 57 patients in the safety population (67 episodes) experienced AEs, most of which were not drug-related. Overall, carglumic acid seems to have a good safety profile for treating hyperammonaemia during OA decompensation. CONCLUSION: Carglumic acid when used with or without ammonia scavengers, is an effective treatment for restoration of normal plasma ammonia concentrations in hyperammonaemic episodes in OA patients.
Assuntos
Amônia/sangue , Glutamatos/uso terapêutico , Hiperamonemia/sangue , Hiperamonemia/tratamento farmacológico , Erros Inatos do Metabolismo dos Aminoácidos/sangue , Erros Inatos do Metabolismo dos Aminoácidos/tratamento farmacológico , Feminino , Humanos , Recém-Nascido , Masculino , Acidemia Propiônica/sangue , Acidemia Propiônica/tratamento farmacológico , Estudos Retrospectivos , Resultado do TratamentoAssuntos
Glutamatos/uso terapêutico , Hiperamonemia/terapia , Acidemia Propiônica/complicações , Amônia/sangue , Relação Dose-Resposta a Droga , Feminino , Seguimentos , Glutamatos/administração & dosagem , Humanos , Hiperamonemia/sangue , Hiperamonemia/etiologia , Recém-Nascido , Acidemia Propiônica/sangue , Acidemia Propiônica/terapia , Diálise Renal , Índice de Gravidade de DoençaRESUMO
BACKGROUND: 3-Hydroxypalmitoleoyl-carnitine (C16:1-OH) has recently been reported to be elevated in acylcarnitine profiles of patients with propionic acidemia (PA) or methylmalonic acidemia (MMA) during expanded newborn screening (NBS). High levels of C16:1-OH, combined with other hydroxylated long chain acylcarnitines are related to long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) and trifunctional protein (TFP) deficiency. METHODS: The acylcarnitine profile of two LCHADD patients was evaluated using liquid chromatography-tandem mass spectrometric method. A specific retention time was determined for each hydroxylated long chain acylcarnitine. The same method was applied to some neonatal dried blood spots (DBSs) from PA and MMA patients presenting abnormal C16:1-OH concentrations. RESULTS: The retention time of the peak corresponding to C16:1-OH in LCHADD patients differed from those in MMA and PA patients. Heptadecanoylcarnitine (C17) has been identified as the novel biomarker specific for PA and MMA patients through high resolution mass spectrometry (Orbitrap) experiments. We found that 21 out of 23 neonates (22 MMA, and 1PA) diagnosed through the Tuscany region NBS program exhibited significantly higher levels of C17 compared to controls. Twenty-three maternal deficiency (21 vitamin B12 deficiency, 1 homocystinuria and 1 gastrin deficiency) samples and 82 false positive for elevated propionylcarnitine (C3) were also analyzed. CONCLUSIONS: We have characterized a novel biomarker able to detect propionate disorders during expanded newborn screening (NBS). The use of this new biomarker may improve the analytical performances of NBS programs especially in laboratories where second tier tests are not performed.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico , Carnitina/análogos & derivados , Carnitina/sangue , Triagem Neonatal , Acidemia Propiônica/sangue , Acidemia Propiônica/diagnóstico , Biomarcadores/sangue , Humanos , Recém-Nascido , Estudos RetrospectivosRESUMO
Propionic academia (PA) occurs because of mutations in the PCCA or PCCB genes encoding the two subunits of propionyl-CoA carboxylase, a pivotal enzyme in the breakdown of certain amino acids and odd-chain fatty acids. There is no cure for PA, but dietary protein restriction and liver transplantation can attenuate its symptoms. We show here that a single intravenous injection of adeno-associated virus 2/8 (AAV8) or AAVrh10 expressing PCCA into PA hypomorphic mice decreased systemic propionylcarnitine and methyl citrate for up to 1.5 years. However, long-term phenotypic correction was always better in male mice. AAV-mediated PCCA expression was similar in most tissues in males and females at early time points and differed only in the liver. Over 1.5 years, luciferase and PCCA expression remained elevated in cardiac tissue for both sexes. In contrast, transgene expression in the liver and skeletal muscles of female, but not male, mice wanedsuggesting that these tissues were major sinks for systemic phenotypic correction. These data indicate that single systemic intravenous therapy by AAV vectors can mediate long-term phenotype correction for PA. However, tissue-specific loss of expression in females reduces efficacy when compared with males. Whether similar sex-biased AAV effects occur in human gene therapy remains to be determined.
Assuntos
Biomarcadores/sangue , Terapia Genética/métodos , Vetores Genéticos/genética , Metilmalonil-CoA Descarboxilase/metabolismo , Acidemia Propiônica/genética , Acidemia Propiônica/terapia , Caracteres Sexuais , Animais , Carnitina/análogos & derivados , Carnitina/sangue , Citratos/sangue , Dependovirus , Feminino , Injeções Intravenosas , Fígado/metabolismo , Luciferases , Masculino , Metilmalonil-CoA Descarboxilase/genética , Camundongos , Músculo Esquelético/metabolismo , Acidemia Propiônica/sangue , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Propionic acidemia (PA) is an autosomal recessive inborn error of metabolism caused by deficiency of propionyl-CoA carboxylase (PCC). This enzyme is composed of six PCCA and six PCCB subunits and mediates a critical step in catabolism of odd chain fatty acids and certain amino acids. Current treatment options for PA are limited to stringent dietary restriction of protein consumption and some patients undergo elective liver transplantation. We previously generated a hypomorphic model of PA, designated Pcca(-/-)(A138T), with 2% of wild-type enzyme activity that mimics many aspects of the human disease. In this study, we used the differing tissue tropisms of adeno-associated virus (AAV) to probe the ability of liver or muscle-directed gene therapy to treat systemic aspects of this disease that affects many cell types. Systemic therapy with muscle-biased AAV1, liver-biased AAV8, and broadly tropic AAVrh10 mediated significant biochemical corrections in circulating propionylcarnitine (C3) and methyl citrate by all vectors. The innate tissue bias of AAV1 and AAV8 gene expression was made more specific by the use of muscle-specific muscle creatine kinase (specifically MCK6) and hepatocyte-specific transthyretin (TTR) promoters, respectively. Under these targeted conditions, both vectors mediated significant long-term correction of circulating metabolites, demonstrating that correction of muscle and likely other tissue types in addition to liver is necessary to fully correct pathology caused by PA. Liver-specific AAV8-TTR-PCCA mediated better correction than AAV1-MCK-PCCA. These data suggest that targeted gene therapy may be a viable alternative to liver transplantation for PA. They also demonstrate the effects of tissue-specific and broad gene therapy on a cell autonomous systemic genetic disease.