Abstract Phenylketonuria (PKU) is caused by deficient activity of phenylalanine hydroxylase (PAH), responsible for the conversion of phenylalanine (Phe) to tyrosine (Tyr). Monitoring of patients with PKU requires the measurement of Phe in plasma using high-performance liquid chromatography (HPLC) or in dried blood spots (DBS) using different techniques to adjust treatment strategy. The objective of this study was to evaluate Phe levels in DBS measured by two different methods and compare them with Phe levels measured in plasma by HPLC. We analyzed 89 blood samples from 47 PKU patients by two different methods: fluorometric method developed in-house (method A) and the commercially available PerkinElmer® Neonatal Phenylalanine Kit (method B) and in plasma by HPLC. The mean Phe levels by method A, method B, and HPLC were 430.4±39.9μmol/L, 439.3±35.4μmol/L, and 442.2±41.6μmol/L, respectively. The correlation values between HPLC and methods A and B were 0.990 and 0.974, respectively (p < 0.001 for both). Our data suggest that methods A and B are useful alternatives for monitoring Phe levels in patients with PKU, with method A being in closer agreement with the reference standard (HPLC).

RESUMO Paciente portadora de deficiência de acil-CoA desidrogenase de cadeia média (MCADD), com episódios clínicos recorrentes de hipoglicemia e alteração de consciência, apresentou alterações no perfil de acilcarnitinas em sangue por espectrometria de massas em tandem e na análise de ácidos orgânicos urinários por cromatografia gasosa acoplada à espectrometria de massa. Este caso demonstra a importância da coleta de amostra biológica em jejum (se possível) quando há suspeita de MCADD e ressalta que o tempo/momento de coleta da amostra biológica é importante para o diagnóstico, considerando a possibilidade de a MCADD ser subdiagnosticada no Brasil.

ABSTRACT Female patient carrier of medium-chain acyl-CoA dehydrogenase deficiency (MCADD) with recurrent clinical episodes of hypoglycemia and altered level of consciousness, presented changes in blood acylcarnitine profile by tandem mass spectrometry and in the urinary organic acid analysis by gas chromatography/mass spectrometry (GC/MS). This case demonstrates the importance of fasting prior biological sample collection (when possible) when MCADD is suspected, and emphasizes that the time/momentum of biological sample collection is crucial to diagnosis, considering the possibility that MCADD is underdiagnosed in Brazil.

RESUMEN Paciente portadora de deficiencia de acil-CoA deshidrogenasa de cadena media (MCADD) con episodios clínicos recurrentes de hipoglucemia y alteración de consciencia presentó mudanzas en el perfil de acilcarnitinas en la sangre con técnicas de espectrometría de masas en tándem y en el análisis de ácidos orgánicos urinarios mediante cromatografía de gases acoplada a espectrometría de masas. Este caso demuestra la importancia de la toma de muestras biológicas en ayunas (se posible) cuando se sospecha de MCADD y destaca que el tiempo/momento de extracción de la muestra biológica es valioso para el diagnóstico, considerando la posibilidad de que la MCADD es subdiagnosticada en Brasil.

Abstract Organic acidurias and aminoacidopathies are groups of frequent inborn errors of metabolism (IEMs), which are caused by mutations in specific genes that lead to loss of protein/enzyme or transport function with important deleterious effects to cell metabolism. Since a considerable number of such disorders are potentially treatable when diagnosed at an early stage of life, diagnosis is crucial for the patients. In the present report, we describe symptomatic individuals referred to our service that were diagnosed with these disorders from 2006 to 2016. We used blood and urine samples from 21,800 patients suspected of aminoacidopathies or organic acidemias that were processed by the analytical techniques reverse phase high-performance liquid chromatography for amino acid quantification and gas chromatography coupled to mass spectrometry for organic acid detection. Analysis of dried blood spots by liquid chromatography-tandem mass spectrometry was used in some cases. We detected 258 cases of organic acidurias, and 117 patients with aminoacidopathies were diagnosed. Once diagnosis was performed, patients were promptly submitted to the available treatments with clear reduction of mortality and morbidity. The obtained data may help pediatricians and metabolic geneticists to become aware of these diseases and possibly expand newborn screening programs in the future.

Abstract Fatty acid oxidation defects (FAODs) are inherited metabolic disorders caused by deficiency of specific enzyme activities or transport proteins involved in the mitochondrial catabolism of fatty acids. Medium-chain fatty acyl-CoA dehydrogenase (MCAD) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiencies are relatively common FAOD biochemically characterized by tissue accumulation of medium-chain fatty acids and long-chain 3-hydroxy fatty acids and their carnitine derivatives, respectively. Patients with MCAD deficiency usually have episodic encephalopathic crises and liver biochemical alterations especially during crises of metabolic decompensation, whereas patients with LCHAD deficiency present severe hepatopathy, cardiomyopathy, and acute and/or progressive encephalopathy. Although neurological symptoms are common features, the underlying mechanisms responsible for the brain damage in these disorders are still under debate. In this context, energy deficiency due to defective fatty acid catabolism and hypoglycemia/hypoketonemia has been postulated to contribute to the pathophysiology of MCAD and LCHAD deficiencies. However, since energetic substrate supplementation is not able to reverse or prevent symptomatology in some patients, it is presumed that other pathogenetic mechanisms are implicated. Since worsening of clinical symptoms during crises is accompanied by significant increases in the concentrations of the accumulating fatty acids, it is conceivable that these compounds may be potentially neurotoxic. We will briefly summarize the current knowledge obtained from patients with these disorders, as well as from animal studies demonstrating deleterious effects of the major fatty acids accumulating in MCAD and LCHAD deficiencies, indicating that disruption of mitochondrial energy, redox, and calcium homeostasis is involved in the pathophysiology of the cerebral damage in these diseases. It is presumed that these findings based on the mechanistic toxic effects of fatty acids may offer new therapeutic perspectives for patients affected by these disorders.

OBJETIVO: o objetivo deste trabalho foi o de verificar a prevalência das acidúrias orgânicas em pacientes brasileiros de alto risco. MÉTODOS: técnicas laboratoriais para a detecção e quantificação de ácidos orgânicos por cromatografia gasosa acoplada à espectrometria de massa foram implantadas em Porto Alegre, Brasil. Foram analisados 1.480 pacientes suspeitos, investigados entre janeiro de 1994 e junho de 2000. RESULTADOS: foram diagnosticados 73 (4,9%) casos de acidemias (acidúrias) orgânicas entre os indivíduos testados. Na maioria desses pacientes a terapia resultou em rápida melhora na sua sintomatologia, distintamente de nossos casos previamente diagnosticados em outros laboratórios na Europa e nos Estados Unidos, quando muitos pacientes faleciam antes que quaisquer medidas pudessem ser tomadas. CONCLUSÕES: estes resultados mostram a importância de diagnosticar as acidúrias orgânicas in loco mesmo em países em desenvolvimento, apesar dos custos extras envolvidos.

OBJECTIVE: to determine the prevalence of organic acidurias in high-risk Brazilian patients. METHODS: laboratory techniques for the detection and quantification of organic acids by gas chromatography/mass spectrometry were implemented in Porto Alegre, Brazil. We investigated 1,480 patients suspected of organic aciduria between January 1994 and June 2000. RESULTS: seventy three (4.9%) cases of organic acidemias (acidurias) were diagnosed among the tested individuals. In most of these patients, prompt therapy resulted in rapid symptom improvement; these results are completely different from our previous cases diagnosed in other laboratories in Europe and the United States, where several patients died before any measures could be taken. CONCLUSIONS: these results demonstrate the importance of diagnosing organic acidurias in loco even in developing countries, in spite of the extra costs involved.

A adrenoleucodistrofia ligada ao X (X-ALD) é uma desordem hereditária do metabolismo peroxissomal, bioquimicamente caracterizada pelo acúmulo de ácidos graxos de cadeia muito longa (`very long chain fatty acids"- VLCFA) em diferentes tecidos e em fluidos biológicos, sendo os principais ácidos acumulados o hexacosanóico (C26:0) e o tetracosanóico (C24:0). O acúmulo destes ácidos graxos está associado com desmielinização cerebral e insuficiência adrenal. A incidência desta condição é estimada em 1 para 25.000 em homens. Pelo menos seis fenótipos podem ser distinguidos, sendo a adrenoleucodistrofia (ALD) cerebral infantil e a adrenomieloneuropatia (AMN) os mais comuns. O tratamento preconizado consiste na utilização da mistura gliceroltrioleato/gliceroltrierucato (GTO/GTE), conhecida como Óleo de Lorenzo, combinada com dieta pobre em VLCFA. Existem ainda, terapias alternativas como transplante de medula óssea e imunossupressão, além da utilização de lovastatina e fenilacetato de sódio. Neste trabalho fez-se uma avaliação do tratamento com Óleo de Lorenzo associado à dieta restrita em VLCFA de 7 pacientes homens com X-ALD analisando a evolução clínica e bioquímica. Os pacientes apresentaram uma redução média de 50% nos valores de C26:0 e de 42,8% na razão C26:0/C22:0 após o início do tratamento. A maioria dos pacientes permaneceu clinicamente bem e aproximadamente 30% dos pacientes apresentaram uma progressão rápida no curso clínico da doença. Parece não haver uma clara correlação bioquímico-clínica do tratamento. Os resultados nos mostram que novas terapias mais eficazes para X-ALD são necessárias para que se possa obter um melhor prognóstico da doença com progressão mais lenta dos sintomas apresentados ou mesmo reversão dos sintomas já presentes nos pacientes.

X-Linked adrenoleukodystrophy (X-ALD) is a hereditary disorder of the peroxisomal metabolism biochemically characterized by the accumulation of very long chain fatty acids (VLCFA) in tissues and biological fluids. The major accumulated acids are hexacosanoic acid (C26:0) and tetracosanoic acid (C24:0). The disorder is characterized clinically by central and peripheral demyelination and adrenal insufficiency closely related to the accumulation of fatty acids. The incidence of X-ALD is estimated to be 1:25,000 males. At least six phenotypes can be distinguished. The most common phenotypes are childhood cerebral ALD and adrenomyeloneuropathy (AMN). The recommended therapy consists of the use of the glyceroltrioleate/glyceroltrierucate (GTO/GTE) mixture, known as Lorenzo's Oil, combined with a VLCFA-poor diet. There are alternative treatments such as bone marrow transplantation and immunosuppression, as well as the use of lovastatin and sodium phenylacetate. In the present study we report the clinical and biochemical course of 7 male patients with X-ALD treated with Lorenzo's Oil and a VLCFA-restricted diet. Treatment produced 50% reduction in C26:0 and 42.8% reduction in the C26:0/C22:0 ratio. Most patients remained clinically well, although approximately 30% of them presented a rapid clinical deterioration. The results showed a poor biochemical-clinical correlation for treatment, indicating that new therapies for X-ALD are needed in order to obtain a better prognosis for patients.

O objetivo deste estudo-piloto foi avaliar a aplicabilidade de protocolo dc triagem para a detecção de erros inatos do metabolismo (EIM) em pacientes de alto risco. O protocolo foi utilizado em 65 pacientes encaminhados ao Laboratório de Genética Médica do Hospital Universitário Prof. Edgard Santos por suspeita de apresentar um EIM. Oito desses pacientes (12,3%) apresentaram resultado anormal no protocolo de triagem. Estes, junto com outros 22, cujo protocolo de triagem teve resultados normais mas que apresentavam sinais ou sintomas clínicos sugestivos de um EIM que poderia passar desapercebido pelos testes realizados, foram selecionados para investigação diagnostica adicional. Em 5 desses 30 pacientes (7,7% da amostra total) foi detectado um EIM. Estes resultados indicam que o protocolo de triagem planejado foi aplicado com sucesso, permitindo a detecção de pacientes afetados em uma frequência comparável à observada em estudos mais amplos realizados em outros locais. A continuação do estudo e a ampliação da amostra vão ajudar a delinear- o perfil dos EIM no nordeste brasileiro, bem como a identificação de número significativo de pacientes e de famílias com EIM, que podem se beneficiar das medidas preventivas e terapêuticas disponíveis para essas doenças.

The purpose of this pilot-study was to evaluate the applicability of a screening protocol for the detection of inborn errors of metabolism (IEM) in high-risk patients. The protocol was applied in 65 patients referred to the Medical Genetics Laboratory of the University Hospital Professor Edgard Santos due to the suspicion of an IEM. Eight of these patients (12.3%) displayed an abnormal result in the screening protocol. These patients, along with 22 who displayed normal results in the screening protocol but who presented clinical symptoms or signs suggestive of an IEM not detectable by the tests applied, were selected for a further diagnostic investigation. In 5 of these 30 patients (7.7% of the total sample) it was possible to establish the diagnosis of an specific IEM. The results indicate that the designed screening protocol was sucessfully applied, allowing the detection of affected patients in a frequency comparable to that observed in larger studies performed elsewhere. The continuation of this study and the enlargement of the sample will help to delineate the profile of IEM in northeast of Brazil and will allow the identification of a significative number of patients and families, who could benefit from the therapeutic and preventive measures available for these diseases.