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.

Colestasis por deficiencia de 3β-Δ5-C27-hidroxiesteroide deshidrogenasa en un paciente con alteración en la síntesis de ácidos biliares / Cholestasis due to deficiency of 3β-Δ5-C27-hydroxysteroid dehydrogenase in a patient with altered bile acid synthesis

Resumen: Introducción: Los errores innatos en la síntesis de ácidos biliares son un grupo de defectos genéticos que representan del 1 al 2% de las enfermedades colestásicas crónicas en lactantes, niños y adolescentes. La deficiencia de 3β-Δ5-C27-hidroxiesteroide oxidoreductasa (3β-HSDH) es el defecto más comúnmente reportado. El cuadro clínico característico consiste en hepatitis neonatal, hepatomegalia, esplenomegalia, malabsorción, desnutrición y enfermedad hepática de aparición tardía. Caso clínico: Lactante masculino con antecedente de ictericia en escleras a los 4 meses que se resolvió espontáneamente; posteriormente, a los 18 meses, presentó enfermedad colestásica. Durante su abordaje se documentó gamma-glutamil transpeptidasa normal, hallazgo que es altamente sugestivo de alteración en la síntesis de ácidos biliares. El diagnóstico se realizó con espectrometría de masas en orina. Se inició tratamiento con ácido cólico oral, y presentó mejoría inmediata. Conclusiones: El resultado en los ácidos biliares urinarios es definitivo para el defecto genético y consistente con mutaciones homocigotas en el gen HSD3B7. Este padecimiento constituye un diagnóstico de exclusión en las enfermedades colestásicas de la infancia, particularmente el hallazgo de gamma-glutamil transpeptidasa normal o levemente aumentada, y responde adecuadamente al tratamiento oral, por lo que debe identificarse de forma temprana.

Abstract: Background: Inborn errors in bile acid synthesis are a group of genetic defects accounting for 1 to 2% of chronic cholestatic diseases in infants, children and adolescents. Deficiency of 3β-Δ5-C27-hydroxysteroid dehydrogenase (3β-HSDH) is the most common defect in this disease. Clinical features consist of neonatal hepatitis, hepatomegaly, splenomegaly, malabsorption, malnutrition, and late-onset liver disease. Case report: A male infant who presented jaundice in sclera at 4 months that resolved spontaneously, later presented cholestatic disease at 18 months. During his approach, normal gamma-glutamyl transpeptidase was documented, a finding that is highly suggestive of alteration in the synthesis of bile acids. The diagnosis was made using urine mass spectrometry. Oral colic acid treatment was started, presenting immediate improvement. Conclusions: The result in urinary bile acids is definitive for the genetic defect and consistent with homozygous mutations in the HSD3B7 gene. This condition is a diagnosis of exclusion in childhood cholestatic diseases, particularly in the presence of normal or mildly enlarged gamma-glutamyl transpeptidase, and responds adequately to oral treatment; it should be identified early.

Apresentação clínica inicial dos casos de erros inatos do metabolismo de um hospital pediátrico de referência: ainda um desafio diagnóstico / Initial clinical presentation in cases of inborn errors of metabolism in a reference children's hospital: still a diagnostic challenge

RESUMO Objetivo: Avaliar a apresentação clínica inicial dos casos com diagnóstico confirmado de erros inatos do metabolismo (EIM) em um serviço de referência em atendimento pediátrico. Métodos: Estudo clínico, observacional, com delineamento transversal e de coleta retrospectiva em consulta ambulatorial de 2009 a 2013. Critério de inclusão: paciente encaminhado para investigação de EIM. Critério de exclusão: diagnóstico prévio de EIM. Variáveis analisadas: dados de identificação; situação atual da investigação diagnóstica; história familiar; apresentação clínica inicial; alterações laboratoriais. Os dados foram analisados por meio de estatística descritiva Resultados: Incluídos 144 pacientes, sendo 62,5% do sexo masculino. A mediana de idade foi de 2,6 anos e a média de 4,3 ± 4,7 anos. Doze pacientes (8,3%) tiveram o diagnóstico confirmado (três com aminoacidopatias, três com acidemias orgânicas, dois com distúrbios do ciclo da ureia e quatro com doenças de depósito lisossômico). Déficit cognitivo e convulsões foram os sinais e sintomas iniciais; seguidos de retardo de crescimento, atraso do desenvolvimento neuropsicomotor, convulsões e hepatomegalia. As principais alterações laboratoriais encontradas foram hiperamonemia e acidose metabólica. Conclusões: O diagnóstico dos EIM ainda traz desafios à prática pediátrica. Neste estudo foram identificados os seguintes fatores: dificuldade de acesso aos exames laboratoriais específicos, reduzido número de especialistas e pouca difusão do conhecimento nas faculdades da área da saúde. O diagnóstico precoce dos EIM tem impacto fundamental no tratamento e prevenção das sequelas, devendo ser considerado já nas hipóteses diagnósticas iniciais.

ABSTRACT Objective: To assess the initial clinical presentation of confirmed cases of inborn errors of metabolism (IEM) at a reference facility for pediatric care. Methods: Cross-sectional, observational and descriptive study with data collection of outpatients, from January 2009 to December 2013. Inclusion criterion: referral to IEM investigation. Exclusion criterion: prior diagnosis of IEM. Analyzed variables: identification data; status of diagnostic investigation; family history of IEM; initial clinical presentation, laboratory abnormalities related to the hypothesis of IEM. Descriptive statistical methods were used in the data analysis. Results: We included 144 patients in the study, of which 62.5% were male. The mean and median ages were, respectively, 4.3 ± 4.7 years and 2.6 years. Twelve patients (8.3%) had a confirmed diagnosis of IEM (three with aminoacidopathies, three with organic acidemias, two with urea cycle disorders and four with lysosomal storage diseases). Cognitive impairment and seizures were the initial signs and symptoms, followed by growth retardation, neuropsychomotor developmental delay, seizures and hepatomegaly. The main laboratory abnormalities in the diagnosis were hyperammonemia and metabolic acidosis. Conclusions: The diagnosis of IEM still creates challenges to the pediatric practice. In this study, we identified the following factors: difficulty to access specific laboratory tests, reduced number of experts and poor dissemination of knowledge among healthcare schools. The early diagnosis of IEM majorly impacts the treatment and prevention of sequelae and should be considered in the initial diagnostic hypotheses.

Reference values of amino acids, acylcarnitines and succinylacetone by tandem mass spectrometry for use in newborn screening in southwest Colombia / Valores de referencia de aminoácidos, acilcarnitinas y succinilacetona por espectrometría de masas en tándem para su uso en el tamizaje neonatal en el suroccidente de Colombia

Abstract Introduction: Inborn errors of metabolism (IEM) represent an important public health problem due to current diagnosis and treatment limitations, poor life quality of affected patients, and consequent untimely child death. In contrast to classical methods, tandem mass spectrometry (MS/MS) has allowed simultaneous evaluation of multiple metabolites associated with IEM offering higher sensitivity, low false positive rates and high throughput. Aims: Determine concentration levels for amino acids and acylcarnitines in blood of newborns from Colombia, to establish reference values for further use in diagnosis of IEM. Methods: Implementation of a method to determine amino acids, acylcarnitines and succinylacetone in newborn dried blood spots using MS/MS, and its application in a cross-sectional study conducted in 891 healthy neonates from Cali and Quibdo cities is described. Results: fifty-seven analytes that allow the diagnosis of more than 40 different pathologies were tested. The method showed to be linear, precise and accurate. Healthy neonates 1-18 days of age were included, 523 from Cali and 368 from Quibdo; 52% male and 48% female. Age-related differences on the concentration levels of amino acids and acylcarnitines were observed whereas no significant differences by gender were found. Conclusion: The study has contributed to reveal the usual concentration levels of amino acids, acylcarnitines and succinylacetone that could be used as reference for the establishment of a newborn metabolic screening program in Colombia.

Resumen Introducción: Los Errores Innatos del metabolismo (EIM) representan un importante problema de salud pública debido a limitaciones en el tratamiento y diagnóstico oportuno, la pobre calidad de vida de los pacientes afectados, así como la muerte infantil prematura. Comparada con los métodos clásicos, la espectrometría de masas en tándem (MS/MS) ha permitido la evaluación simultánea de múltiples metabolitos asociados con EIM, con una alta sensibilidad, baja proporción de falsos positivos y alto rendimiento. Objetivos: Determinar los niveles de concentración de aminoácidos y acilcarnitinas en sangre de recién nacidos de Colombia, para establecer los valores normales para usarlos como referencia en el diagnóstico de EIM. Métodos: Aquí, se describe la implementación de un método para determinar aminoácidos, acilcarnitinas y succinilacetona en gotas de sangre seca de recién nacidos usando MS/MS, y su aplicación en un estudio de corte transversal realizado en 891 neonatos sanos de las ciudades de Cali y Quibdó. Resultados: Se evaluaron 57 analitos que permiten el diagnóstico de más de 40 patologías diferentes. El método mostró ser lineal, preciso y exacto. Se incluyeron neonatos sanos de 1-18 días de edad, 523 de Cali y 368 de Quibdó, 52% hombres y 48% mujeres. Se observaron diferencias en los niveles de concentración de aminoácidos y acilcarnitinas relacionadas con la edad, mientras que no se encontraron diferencias significativas por sexo. Conclusión: El estudio ha contribuido a revelar los niveles usuales de concentración de aminoácidos, acilcarnitinas y succinilacetona que pueden ser usados como referencia para el establecimiento del programa de tamizaje neonatal metabólico en Colombia.

Metabolic screening and metabolomics analysis in the Intellectual Developmental Disorders Mexico Study / Tamiz bioquímico y metabolómico en el estudio de los trastornos del desarrollo intelectual en México

Abstract: Objective: Inborn errors of metabolism (IEM) are genetic conditions that are sometimes associated with intellectual developmental disorders (IDD). The aim of this study is to contribute to the metabolic characterization of IDD of unknown etiology in Mexico. Materials and methods: Metabolic screening using tandem mass spectrometry and fluorometry will be performed to rule out IEM. In addition, target metabolomic analysis will be done to characterize the metabolomic profile of patients with IDD. Conclusion: Identification of new metabolomic profiles associated with IDD of unknown etiology and comorbidities will contribute to the development of novel diagnostic and therapeutic schemes for the prevention and treatment of IDD in Mexico.

Resumen: Objetivo: Los errores innatos del metabolismo (EIM) son condiciones genéticas que pueden asociarse con trastornos del desarrollo intelectual (TDI). El objetivo de este estudio es contribuir a la caracterización metabólica de los pacientes con TDI de etiología desconocida. Material y métodos: Se realizará un tamiz metabólico mediante espectrometría de masas-tándem y fluorometría para descartar EIM; además, se analizará el perfil metabolómico de los pacientes con TDI. Conclusión: La identificación de perfiles metabolómicos asociados con los TDI de etiología desconocida contribuirá al desarrollo de nuevos esquemas diagnósticos y terapéuticos para la prevención y tratamiento de los TDI en México.

Case report of myeloperoxidase deficiency associated with disseminated paracoccidioidomycosis and peritoneal tuberculosis

Abstract Myeloperoxidase (MOP) is present in monocyte and neutrophil lysosomes, catalyzing hydrogen peroxide and chloride ion conversion to hypochlorous acid. MOP seems to destroy pathogens during phagocytosis by neutrophils and is considered an important defense against innumerous bacteria. We present a patient who had MOP deficiency, who presented with a subacute form of paracoccidioidomycosis and later with peritoneal tuberculosis. MOP deficiency leads to the diminished destruction of phagocytized pathogens. This case gives important evidence of an association between MOP deficiency and increased susceptibility to infection by Paracoccidioides brasiliensis and Mycobacterium tuberculosis.

A Population-Based Genomic Study of Inherited Metabolic Diseases Detected Through Newborn Screening

BACKGROUND: A newborn screening (NBS) program has been utilized to detect asymptomatic newborns with inherited metabolic diseases (IMDs). There have been some bottlenecks such as false-positives and imprecision in the current NBS tests. To overcome these issues, we developed a multigene panel for IMD testing and investigated the utility of our integrated screening model in a routine NBS environment. We also evaluated the genetic epidemiologic characteristics of IMDs in a Korean population. METHODS: In total, 269 dried blood spots with positive results from current NBS tests were collected from 120,700 consecutive newborns. We screened 97 genes related to NBS in Korea and detected IMDs, using an integrated screening model based on biochemical tests and next-generation sequencing (NGS) called NewbornSeq. Haplotype analysis was conducted to detect founder effects. RESULTS: The overall positive rate of IMDs was 20%. We identified 10 additional newborns with preventable IMDs that would not have been detected prior to the implementation of our NGS-based platform NewbornSeq. The incidence of IMDs was approximately 1 in 2,235 births. Haplotype analysis demonstrated founder effects in p.Y138X in DUOXA2, p.R885Q in DUOX2, p.Y439C in PCCB, p.R285Pfs*2 in SLC25A13, and p.R224Q in GALT. CONCLUSIONS: Through a population-based study in the NBS environment, we highlight the screening and epidemiological implications of NGS. The integrated screening model will effectively contribute to public health by enabling faster and more accurate IMD detection through NBS. This study suggested founder mutations as an explanation for recurrent IMD-causing mutations in the Korean population.

Errores innatos del metabolismo / Inborn errors of metabolism

Los Errores Innatos del Metabolismo (EIM) son un grupo de condiciones caracterizadas por el acúmulo de sustancias tóxicas producido habitualmente por un defecto enzimático. Su relevancia dentro del grupo de las Enfermedades Raras, es que son consideradas hoy un conjunto de patologías tratables, ya que han sido particularmente beneficiadas por leyes de drogas huérfanas, permitiendo el acceso a terapias seguras y eficaces en tratar sus síntomas y la causa que las produce. Su diagnóstico se debe sospechar clínicamente ante ciertos patrones de síntomas y signos, y con un laboratorio sencillo disponible en todos los hospitales y clínicas de Chile, se puede acceder fácilmente a una aproximación inicial, confirmada por estudios realizados en centros de referencia. Su tratamiento debe ser instaurado oportunamente para evitar el desarrollo de secuelas irreparables. La existencia de Programas de Pesquisa Neonatal es la aproximación diagnóstica ideal para llegar precozmente al diagnóstico de estas condiciones.

Inborn Errors of Metabolism are a group of conditions characterized by the accumulation of toxic substances commonly produced by an enzymatic defect. Its relevance within the group of rare diseases is that they are considered today a set of treatable pathologies, as they have been particularly benefit from orphan drug laws, allowing access to safe and effective therapies to treat their symptoms. Its diagnosis should be suspected clinically to certain patterns of symptoms and signs, and with a simple laboratory available in all Hospitals and Clinics Chile can easily earn an initial approximation, to be confirmed by studies in reference centers. The treatment should be started promptly to prevent the development of irreversible sequelae. The existence of Newborn Screening Programs is ideal for reaching early diagnosis and treatment of these conditions.

Orientación diagnóstica de las enfermedades neurometabólicas basada en la clínica, estudios metabólicos y neuroimagenológicos / [Guidelines for detection of inborn errors of metabolism based on clinical exam, analytical studies and neuroimaging techniques].

Neurometabolic disorders constitute an expanding and complex field in which it is difficult to diagnose and to acquire a specific education and training. This article tries to develop a practical orientation in the suspicion, clinical exam, biochemical studies and neuroimaging techniques for the detection of inborn errors of metabolism. It is very important for the neuropediatrician to suspect metabolic diseases depending on some of the most frequent unexplained neurological disturbances and symptoms as psychomotor delay, mental retardation, refractory epilepsy, dystonia, metabolic crisis or other extraneurological signs. It is important the diagnosis related to the new emergent therapeutic options, genetic counseling and prenatal diagnosis.

Avaliação antropométrica de pacientes com suspeita de erros inatos do metabolismo / Anthropometric evaluation of patients with suspected innate errors of metabolism

Avaliar antropometricamente os pacientes com suspeita de erros inatos do metabolismo (EIM) e descrever a prevalência de distúrbios nutricionais (desnutrição, sobrepeso e obesidade). MÉTODOS: foram avaliados 55 pacientes de 0 a 10 anos, de acordo com os índices antropométricos (A/I, P/I E P/A e IMC/I), no laboratório de erros inatos do metabolismo (LEIM) da Universidade Federal do Pará, através de balança e antropômetro. Os dados foram coletados a partir da ficha de atendimento do LEIM. Para o diagnóstico nutricional foram utilizados os programas Anthro e Anthro Plus e o programa SPSS para a análise estatística. RESULTADOS: os pacientes atendidos pertenciam, na maioria, a faixa etária de sete meses a nove anos. Os principais sintomas foram atraso no desenvolvimento neuropsicomotor e infecções frequentes. Quanto ao estado nutricional, foi observado déficit de 23,7 por cento no indicador de peso para idade, déficit de 50,9 por cento no indicador de altura para idade, excesso de peso e obesidade de 15,4 por cento para peso para altura, e 25,1 por cento para índice de massa corporal para idade. CONCLUSÕES: os pacientes apresentaram estado nutricional inadequados, o qual na ausência de diagnóstico de EIM, os fatores envolvidos devem ser mais bem averiguados...

To provide an anthropometric evaluation of patients suspected of having innate errors of metabolism (IEMs) and report the prevalence of nutritional disorders (malnutrition, overweight and obesity). METHODS: fifty-five patients aged between 0 and 10 years were evaluated for anthropometric indices (H/A, W/A and W/H and BMI/A), in the innate errors of metabolism laboratory (LEIM) of the Federal University of Pará, using scales and an anthropometer. The data were collected using an LEIM form. Nutritional diagnosis was carried out using the Anthro and Anthro Plus programs and the SPSS statistics package. RESULTS: the patients attended were mostly aged between seven months and nine years. The main symptoms were delayed neuropsychomotor development and frequent infections. As for the nutritional status, a deficit of 23.7 percent was observed in weight for age, a deficit of 50.9 percent in height for age, and the prevalence of overweight and obesity was 15.4 percent according to weight for height, and 25,1 percent according to body mass index for age. CONCLUSIONS: the nutritional status of the patients was inadequate and, given the absence of a diagnosis of IEMs, the factors involved should be investigated more thoroughly...

Deficiencia de 3-hidroxiacil coA deshidrogenasa de cadena larga, asociación con HELLP y hallazgos en la espectroscopia por resonancia magnética / Long chain 3-hydroxyacyl-coA dehydrogenase deficiency, asociation with HELLP and magnetic resonance spectroscopy findings

La deficiencia de 3-hidroxiacil coA deshidrogenasa de cadena larga (LCHAD) es uno de los trastornos de la betaoxidación de ácidos grasos. La presentación clínica más frecuente incluye trastornos de conciencia, hipoglucemia y disfunción hepática gatillados por ayuno prolongado o infecciones. Una vez desencadenada, la crisis metabólica presenta alta mortalidad. El síndrome HELLP y la hepatitis grasa aguda del embarazo (AFLP) son trastornos del tercer trimestre del embarazo. Se ha asociado estas enfermedades durante la gestación con defectos hereditarios de la betaoxidación en el feto. Comunicamos el caso clínico de un trastorno de beta oxidación (deficiencia de LCHAD) asociado a HELLP materno. Describimos como hallazgos en la resonancia magnética espectroscópica un pico de ácido láctico y lípidos significativo. La pesquisa de estos trastornos de la betaoxidación al nacimiento, ante el antecedente de HELLP materno, permite el diagnóstico de la enfermedad previo al desarrollo de los síntomas.

LCHAD deficiency is a disorder of fatty acid beta oxidation. The most common clinical presentation includes disorders of consciousness, hypoglycemia and liver dysfunction triggered by prolonged fasting or infection. Once a metabolic crisis is triggered, there is a high mortality. HELLP syndrome and acute fatty liver failure of pregnancy (AFLP) are disorders of the third trimester of pregnancy. These diseases have been associated during pregnancy with hereditary defects of beta-oxidation in the fetus. We report a case of beta-oxidation disorder (LCHAD deficiency) associated with maternal HELLP. We described a peak of lipid and lactic on magnetic resonance spectroscopic of this patient. The investigation of these beta-oxidation disorders at birth, with a history of maternal HELLP, allows the diagnosis of the disease prior to developing symptoms.

Identification of SLC26A3 Mutations in a Korean Patient with Congenital Chloride Diarrhea

Congenital chloride diarrhea (CLD) is an autosomal recessive disorder with the hallmark of persistent watery Cl(-)-rich diarrhea from birth. Mutations in the solute carrier family 26, member 3 (SLC26A3) gene, which encodes a coupled Cl-/HCO3- exchanger in the ileum and colon, are known to cause CLD. Although there are a few reports of CLD patients in Korea, none of these had been confirmed by genetic analysis. Here, we describe the case of a Korean infant with clinical features of CLD. Using direct sequencing analysis, we identified 2 sequence variants: a missense variant of unknown significance (c.525G>C; p.Arg175 Ser) and a splicing mutation (c.2063-1G>T) in the SLC26A3 gene; these had been inherited from the father and mother, respectively. Whilst CLD is rare, its main symptom, diarrhea, is very common in infants. Hence, the diagnosis of CLD can prove difficult. Mutational analysis of the SLC26A3 gene should be considered as a viable method to confirm a diagnosis of CLD in Korean infants with persistent diarrhea.

Tamiz de los errores innatos del metabolismo por espectrometría de masas en tándem: principales biomarcadores / Tandem mass spectrometry as screening for inborn errors of metabolism

The use of tandem mass spectrometry for the diagnosis of inborn errors of metabolism has the potential to expand the newborn screening panel to include a vast number of diseases. This technology allows the detection, in the same spot of dried blood on filter paper and during one single analytical run, of different metabolic diseases. Tandem mass spectrometry is rapidly replacing the classical screening techniques approach of one-metabolite detected per analysis per disease by its ability of simultaneous quantification of several metabolites as markers of many diseases, such as acylcarnitines and amino acids. It is clear that a single metabolite can be a biomarker for several diseases, so the multiplex approach of using tandem mass spectrometry enhances, on average, the sensitivity and specificity of the screening. However, there are differences for particular metabolites and the diseases they detect within the same method. Disorders such as the tyrosinemias and among the organic acidemias, the methylmalonic acidemias, have a substantially higher false-positive rate than other more common metabolic diseases such as medium-chain acyl-CoA dehydrogenase deficiency and phenylketonuria. Before introducing this technology into routine newborn screening programs it is necessary to consider the frequency of each disease, as well as the response to early treatment or variables related to the collection of the sample.

Erros inatos do metabolismo confirmados no Hospital das Clínicas de Ribeirão Preto-SP no período de 2000 a 2008 / Inborn errors of metabolism in the Hospital of Clinics of Ribeirão Preto - SP from 2000 to 2008

Os Erros Inatos do Metabolismo (EIM) vêm sendo cada vez mais identificados nos últimos anos. A preocupação com o diagnóstico precoce decorre do foco na prevenção de deficiências, especialmente a mental. Este estudo descritivo teve por objetivo verificar diagnósticos confirmados e modalidades de tratamento utilizadas de janeiro de 2000 a dezembro de 2008. Método: foi realizada busca ativa de casos confirmados nos serviços que atendem esse tipo doença: neurologia (neuropediatria e doençasneuromusculares), pediatria (serviço de gastrologia e hepatologia) e genética clínica, além de levantamento no Serviço de Arquivo Médico do HCFMRP-USP. Foram confirmados 165 pacientes com EIM, com idades de um dia a 22 anos (mediana de um ano); 50 casos foram defeitos na síntese ou catabolismo de moléculas complexas, 65 no metabolismo intermediário, e 50 na produção ou utilização de energia. O tratamento foi instituído para 12 dos 50 pacientes do grupo I sendo reposição enzimática em 11 e transplante de medula óssea em um; todos do grupo II e III receberam orientação nutricional; 60 do grupo II receberam fórmula dietética industrializada; dos 50 do grupo III, 43 com mitocondriopatias receberam L-carnitina e coenzimas e aqueles com glicogenose, orientação sobre aporte de carbohidratos. A formação de novos recursos humanos, integração com a Rede EIM Brasil e linhas de pesquisa na área são prioridades para melhorar a acuidade na detecção e tratamento de erros inatos do metabolismo.

Inborn Errors of Metabolism have been increasingly identified in recent years. The early diagnosis focuses on prevention of disabilities, especially mental retardation. This descriptive study aims to verify confirmed diagnosis and treatment modalities in HCFMRP-USP cases from January of 2000 to December of 2008. A total of 165 patients with ages ranging from one day to 22 years (median one year) were detected. Fifty patients had synthesis or catabolism of complex molecules (group I), 65 intermediary metabolism (group II), and 50 had production or use of energy (group III) defects. Among the patients of group I, 11 had enzyme replacement therapy, and one bone marrow transplantation; for group II and III, inaddition to daily nutritional guidance for all of the patients, 60 from group II received industrialized diets; from group III, 43 with mitochondrial diseases received L-carnitine and coenzymes, and those with glycogenosis were focused mainly on the intake of carbohydrates. New human resources, integration with the Network EIM Brazil and lines of research in the area are priorities for improving the accuracy in the detection and treatment of inborn errors of metabolism.

Tamizaje neonatal por espectrometría de masas en tándem: actualización / Neonatal screening by tandem mass spectrometry: an update

La espectrometría de masas en tándem (MS/MS) ha posibilitado la expansión de los programas de tamizaje neonatal en diferentes países. Esta tecnología permite el diagnóstico múltiple y rápido de diversos errores innatos del metabolismo. Sin embargo, su aplicación en distintos programas en el ámbito mundial es actualmente muy heterogénea. Existen diferentes criterios para determinar si se incluye una enfermedad específica en esos programas, en algunos casos con un enfoque más restrictivo que en otros, de acuerdo con los principios tradicionales de tamizaje enunciados por Wilson y Jungner, los que habrán de ser reevaluados a la luz de esta nueva tecnología. En este trabajo se presenta una actualización sobre el uso de la MS/MS en diferentes regiones del mundo en relación con las enfermedades tamizadas y con los criterios de inclusión de nuevos problemas de salud en los programas de tamizaje neonatal.

Tandem mass spectrometry (MS/MS) has made it possible to expand neonatal screening programs in different countries. This technology permits multiple and rapid diagnosis of diverse inborn errors of metabolism. However, its use in different programs around the world currently varies widely. There are different criteria for determining whether to include a specific disease in such programs, with some cases employing a more restrictive approach than others, based on the traditional screening principles enunciated by Wilson and Jungner, which will have to be reevaluated in light of this new technology. This article presents an update on the use of MS/MS in different regions of the world in terms of the diseases screened for, and the criteria for including new health problems in neonatal screening programs.

Errores innatos del metabolismo: una aproximación diagnóstica / Inborn errors of metabolism: a diagnostic approach

Los errores innatos del metabolismo (EIM), son enfermedades hereditarias, que obedecen generalmente a alteraciones enzimáticas. Al considerarlas en particular son raras, pero en conjunto representan una importante causa de morbi-mortalidad en la edad pediátrica. El diagnóstico es complicado, ya que las presentaciones clínicas son variadas y poco especificas, y además requieren de investigaciones de laboratorio especializadas. Se clasifican en tres grandes grupos, de acuerdo a los mecanismos fisiopatológicos implicados: los trastornos del metabolismo intermediario, los que obedecen al déficit en la producción de energía y por depósitos de macromoléculas. El conocimiento de los EIM por parte del clínico es fundamental, esto permitirá identificar los datos orientadores de la historia médica y del laboratorio, y solicitar las investigaciones requeridas para un diagnóstico temprano y un tratamiento oportuno.

The inborn errors of metabolism are hereditary diseases caused in most of the cases by enzimatic disturbs. These diseases are rare, but all of them are a very much important cause of morbi – mortality in children. The diagnoses is complicated because clinical presentations are so many and some specific and besides require specialized laboratory investigations. These diseases are classified in three groups, in order to the pshysiopathological mechanisms implicated: intermediary metabolism trastorns, energy production deficit and macromolecules depots. The clinician knowledgement about these diseases is crucial, because it will allow to identify clinical and laboratory dates and apply for required investigations in order to an early diagnosis and opportune treatment.