Influence of initial clinical suspicion on the diagnostic yield of laboratory enzymatic testing in lysosomal storage disorders. Experience from a multispecialty hospital.

Lysosomal storage disorders (LSD) are a group of inherited metabolic diseases mainly caused by a deficiency of lysosomal hydrolases, resulting in a gradual accumulation of non-degraded substrates in different tissues causing the characteristic clinical manifestations of such disorders. Confirmatory tests of suspected LSD individuals include enzymatic and genetic testing. A well-oriented clinical suspicion can improve the cost-effectiveness of confirmatory tests and reduce the time expended to achieve the diagnosis. Thus, this work aims to retrospectively study the influence of clinical orientation on the diagnostic yield of enzymatic tests in LSD by retrieving clinical, biochemical, and genetic data obtained from subjects with suspicion of LSD. Our results suggest that the clinical manifestations at the time of diagnosis and the initial clinical suspicion can have a great impact on the diagnostic yield of enzymatic tests, and that clinical orientation performed in specialized clinical departments can contribute to improve it. In addition, the analysis of enzymatic tests as the first step in the diagnostic algorithm can correctly guide subsequent confirmatory genetic tests, in turn increasing their diagnostic yield. In summary, our results suggest that initial clinical suspicion plays a crucial role on the diagnostic yield of confirmatory enzymatic tests in LSD.

Lysosomal lipid alterations caused by glucocerebrosidase deficiency promote lysosomal dysfunction, chaperone-mediated-autophagy deficiency, and alpha-synuclein pathology.

Mutations in the GBA gene that encodes the lysosomal enzyme ß-glucocerebrosidase (GCase) are a major genetic risk factor for Parkinson's disease (PD). In this study, we generated a set of differentiated and stable human dopaminergic cell lines that express the two most prevalent GBA mutations as well as GBA knockout cell lines as a in vitro disease modeling system to study the relationship between mutant GBA and the abnormal accumulation of α-synuclein. We performed a deep analysis of the consequences triggered by the presence of mutant GBA protein and the loss of GCase activity in different cellular compartments, focusing primarily on the lysosomal compartment, and analyzed in detail the lysosomal activity, composition, and integrity. The loss of GCase activity generates extensive lysosomal dysfunction, promoting the loss of activity of other lysosomal enzymes, affecting lysosomal membrane stability, promoting intralysosomal pH changes, and favoring the intralysosomal accumulation of sphingolipids and cholesterol. These local events, occurring only at a subcellular level, lead to an impairment of autophagy pathways, particularly chaperone-mediated autophagy, the main α-synuclein degradative pathway. The findings of this study highlighted the role of lysosomal function and lipid metabolism in PD and allowed us to describe a molecular mechanism to understand how mutations in GBA can contribute to an abnormal accumulation of different α-synuclein neurotoxic species in PD pathology.

Error innat del metabolisme diagnosticat després d'encefalopatia hiperamonièmica induïda per valproat / Error innato del metabolismo diagnosticado tras encefalopatía hiperamoniémica inducida por valproato / Inborn error of metabolism diagnosed after valproate -induced hyperammonemic encephalopathy

Introducció: L’àcid valproic és un fàrmac antiepilèptic utilitzat àmpliament, tant per tractar l’epilèpsia com en patologia psiquiàtrica o migranya. Tot i que els seus efectessecundaris més freqüents són lleus i coneguts, determinatspacients poden presentar reaccions idiosincràtiques menysconegudes i potencialment greus. Cas clínic: Pacient de 10 anys amb antecedent d’epilèpsia,en el moment actual sense tractament. En el context denova crisi i administració d’àcid valproic, presenta un quadre d’instauració gradual caracteritzat per somnolència,vòmits i alteració conductual amb agressivitat verbal i física. Davant la sospita de reacció adversa farmacològica,se sol·liciten nivells plasmàtics de valproat (normals), nivells d’amoni (elevats) i funció hepàtica i renal (normals). L’electroencefalograma evidencia un alentiment generalitzat compatible amb encefalopatia. L’estudi metabòlic ensang i orina identifica alteracions compatibles amb un trastorn de la β-oxidació dels àcids grassos de cadena mitjana. L’estat clínic del pacient millora al cap de 48 hores del’ingrés amb la retirada del fàrmac, dieta absoluta ambseroterapia i administració de carnitina i àcid carglúmic. Comentaris: Per la seva simptomatologia inespecífica,l’encefalopatia per àcid valproic es pot confondre amb altres patologies, per la qual cosa és important tenir un elevat índex de sospita i fer estudis bioquímics complerts,tant per confirmar el diagnòstic com per excloure altresmalalties de base.(AU)

Introducción: El ácido valproico es un antiepiléptico muy empleadopara el tratamiento de distintas formas de epilepsia, además depara patología psiquiátrica o migraña. Aunque sus efectos adversos son en su mayoría leves y bien conocidos, algunos pacientespueden presentar reacciones idiosincráticas menos conocidas ypotencialmente graves. Caso clínico: Paciente de 10 años, con antecedentes de epilepsia,actualmente sin tratamiento. Tras una nueva crisis y en tratamiento con ácido valproico, presenta un cuadro de instauración radual con somnolencia, vómitos y alteración conductual conagresividad verbal y física. Ante la sospecha de una reacción farmacológica adversa, se solicitan niveles plasmáticos de valproato(normales), niveles de amonio (elevados) y función hepatorrenal(normal). El electroencefalograma evidencia un enlentecimientogeneralizado compatible con encefalopatía. El estudio metabólicoen sangre y orina identifica alteraciones compatibles con un defecto en la β-oxidación de los ácidos grasos de cadena media. Elestado clínico del paciente mejoró a las 48 horas del ingreso conla retirada del fármaco, dieta absoluta y sueroterapia, administración de carnitina endovenosa y ácido carglúmico.Comentarios: Por su sintomatología inespecífica, la encefalopatíapor ácido valproico puede confundirse con otras entidades, por loque es importante tener un alto índice de sospecha y realizar estudios bioquímicos completos tanto para la confirmación del diagnóstico como para excluir otras enfermedades de base.(AU)

Introduction: Valproic acid is an antiepileptic drug that is commonly used not only to treat epilepsy, but also for several psychiatric conditions and migraine. Most of its side effects are mild andwell known. However, some patients may present less knownidiosyncratic, potentially life-threatening side effects. Case report: A 10-year-old boy with history of epilepsy, currently offtreatment, presented with a new seizure. After treatment with valproic acid was initiated, the patient progressively developed altered consciousness with drowsiness, vomiting and physical andverbal aggressiveness. Valproate plasma levels and liver and renalfunction were withing normal limits, but ammonia levels were elevated. An electroencephalogram showed diffuse slow wave activity,suggestive of encephalopathy. Metabolic studies, in blood andurine, identified alterations on β-oxidation of medium chain fattyacid pathways. The patient’s clinical condition improved within 48hours after discontinuation of valproic acid, fasting, and administration of intravenous fluids, carglumic acid and carnitine. Comments: Because of its unspecific symptoms, hyperammonemicencephalopathy induced by valproate can be confused with otherillnesses. For this reason, it is important to have a high level ofsuspicion and perform a comprehensive laboratory evaluation toconfirm the diagnosis and rule out other conditions.(AU)

Early Diagnosis and Treatment of Purine Nucleoside Phosphorylase (PNP) Deficiency through TREC-Based Newborn Screening.

Purine nucleoside phosphorylase (PNP) deficiency is a rare inherited disorder, resulting in severe combined immunodeficiency. To date, PNP deficiency has been detected in newborn screening only through the use of liquid chromatography tandem mass spectrometry. We report the first case in which PNP deficiency was detected by TREC analysis.

Biomarkers in Fabry Disease. Implications for Clinical Diagnosis and Follow-up.

Fabry disease (FD) is a lysosomal storage disorder caused by deficient alpha-galactosidase A activity in the lysosome due to mutations in the GLA gene, resulting in gradual accumulation of globotriaosylceramide and other derivatives in different tissues. Substrate accumulation promotes different pathogenic mechanisms in which several mediators could be implicated, inducing multiorgan lesions, mainly in the kidney, heart and nervous system, resulting in clinical manifestations of the disease. Enzyme replacement therapy was shown to delay disease progression, mainly if initiated early. However, a diagnosis in the early stages represents a clinical challenge, especially in patients with a non-classic phenotype, which prompts the search for biomarkers that help detect and predict the evolution of the disease. We have reviewed the mediators involved in different pathogenic mechanisms that were studied as potential biomarkers and can be easily incorporated into clinical practice. Some accumulation biomarkers seem to be useful to detect non-classic forms of the disease and could even improve diagnosis of female patients. The combination of such biomarkers with some response biomarkers, may be useful for early detection of organ injury. The incorporation of some biomarkers into clinical practice may increase the capacity of detection compared to that currently obtained with the established diagnostic markers and provide more information on the progression and prognosis of the disease.

[50 years of the Neonatal Screening Program in Catalonia.] / 50 años del Programa de Cribado Neonatal en Cataluña.

The Catalonian Newborn Screening Program (CNSP) began in 1969, in Barcelona. It was promoted by Dr. Juan Sabater Tobella and supported by Barcelona Provincial Council and Juan March Foundation. That is how the Institute of Clinical Biochemistry was born, whose aims were diagnosis, research and teaching, along with the spirit of contributing to the prevention of mental retardation. The CNSP began with the detection of phenylketonuria (PKU), and, in 1982, the Program was expanded with the inclusion of congenital hypothyroidism detection. Towards 1990, the Program covered almost 100% of all newborns (NB) in Catalonia. In 1999, the CNSP was expanded with the incorporation of cystic fibrosis. It took fourteen years, until 2013, to make the largest expansion so far, with the incorporation of 19 metabolic diseases to the screening panel. The detection of sickle cell disease began in 2015 and in 2017 the detection of severe combined immunodeficiency was included. Currently, the CNSP includes 24 diseases in its main panel. Since 1969, 2,787,807 NBs have been screened, of whom 1,724 have been diagnosed with any of these diseases, and 252 of other disorders by differential diagnosis with those included in the main panel. The global prevalence is 1: 1,617 NBs affected by any of the diseases included in the CNSP and 1: 1,140 NBs if incidental findings diagnosed through the CNSP are included.

El Programa de Cribado Neonatal de Cataluña (PCNC) se inició en el año 1969, en Barcelona, impulsado por el Dr. Juan Sabater Tobella y apoyado por la Diputación de Barcelona y la Fundación Juan March. Así nació el Instituto de Bioquímica Clínica para acometer funciones asistenciales, de investigación y docencia, con el espíritu de contribuir a la prevención del retraso mental. El PCNC se inició con la detección de la fenilcetonuria (PKU) y en el año 1982 se amplió con la detección del hipotiroidismo congénito. Hacia el año 1990 la cobertura territorial llegó casi al 100% de todos los recién nacidos en Cataluña. En 1999 se amplió el PCNC con la incorporación de la fibrosis quística y tras catorce años, en 2013, se realizó la ampliación más numerosa hasta ahora, con la incorporación de la detección de 19 enfermedades metabólicas hereditarias. En el año 2015 comenzó la detección de la enfermedad de células falciformes y en el 2017 la detección de la inmunodeficiencia combinada grave. Actualmente, el PCNC incluye la detección de 24 enfermedades. Desde su inicio en el año 1969, se han cribado 2.787.807 recién nacidos, de los cuales 1.724 han sido diagnosticados de alguna de las 24 enfermedades que componen nuestro panel principal y 252 por diagnóstico diferencial de las primeras. En total la prevalencia global es de 1:1.617 RN afectos de alguna de las enfermedades incluidas en el PCNC y de 1:1.140 RN si se incluyen los hallazgos incidentales encontrados.

50 años del Programa de Cribado Neonatal en Cataluña / 50 years of the Neonatal Screening Program in Catalonia

El Programa de Cribado Neonatal de Cataluña (PCNC) se inició en el año 1969, en Barcelona, impulsado por el Dr. Juan Sabater Tobella y apoyado por la Diputación de Barcelona y la Fundación Juan March. Así nació el Instituto de Bioquímica Clínica para acometer funciones asistenciales, de investigación y docencia, con el espíritu de contribuir a la prevención del retraso mental. El PCNC se inició con la detección de la fenilcetonuria (PKU) y en el año 1982 se amplió con la detección del hipotiroidismo congénito. Hacia el año 1990 la cobertura territorial llegó casi al 100% de todos los recién nacidos en Cataluña. En 1999 se amplió el PCNC con la incorporación de la fibrosis quística y tras catorce años, en 2013, se realizó la ampliación más numerosa hasta ahora, con la incorporación de la detección de 19 enfermedades metabólicas hereditarias. En el año 2015 comenzó la detección de la enfermedad de células falciformes y en el 2017 la detección de la inmunodeficiencia combinada grave. Actualmente, el PCNC incluye la detección de 24 enfermedades. Desde su inicio en el año 1969, se han cribado 2.787.807 recién nacidos, de los cuales 1.724 han sido diagnosticados de alguna de las 24 enfermedades que componen nuestro panel principal y 252 por diagnóstico diferencial de las primeras. En total la prevalencia global es de 1:1.617 RN afectos de alguna de las enfermedades incluidas en el PCNC y de 1:1.140 RN si se incluyen los hallazgos incidentales encontrados

The Catalonian Newborn Screening Program (CNSP) began in 1969, in Barcelona. It was promoted by Dr. Juan Sabater Tobella and supported by Barcelona Provincial Council and Juan March Foundation. That is how the Institute of Clinical Biochemistry was born, whose aims were diagnosis, research and teaching, along with the spirit of contributing to the prevention of mental retardation. The CNSP began with the detection of phenylketonuria (PKU), and, in 1982, the Program was expanded with the inclusion of congenital hypothyroidism detection. Towards 1990, the Program covered almost 100% of all newborns (NB) in Catalonia. In 1999, the CNSP was expanded with the incorporation of cystic fibrosis. It took fourteen years, until 2013, to make the largest expansion so far, with the incorporation of 19 metabolic diseases to the screening panel. The detection of sickle cell disease began in 2015 and in 2017 the detection of severe combined immunodeficiency was included. Currently, the CNSP includes 24 diseases in its main panel. Since 1969, 2,787,807 NBs have been screened, of whom 1,724 have been diagnosed with any of these diseases, and 252 of other disorders by differential diagnosis with those included in the main panel. The global prevalence is 1: 1,617 NBs affected by any of the diseases included in the CNSP and 1: 1,140 NBs if incidental findings diagnosed through the CNSP are included

Miocardiopatía en niños con errores innatos del metabolismo: descripción de 12 casos / Cardiomyopathy and inborn errors of metabolism in children. Study of 12 cases

Fundamento y objetivo: La miocardiopatía en la infancia es una entidad poco frecuente. Los errores innatos del metabolismo (EIM) pueden causar afectación del miocardio por diversos mecanismos fisiopatológicos.Pacientes y método: Menores de 16 años diagnosticados de miocardiopatía y EIM en un período de 11 años (1998-2009). Resultados: Se han estudiado 12 pacientes (8% del total de miocardiopatías), 9 niños y 3 niñas, con una edad mediana al diagnóstico de 6 meses (rango, nacimiento-8,8 años). El 50% comenzaron con sintomatología cardiaca, y la descompensación cardiaca es la forma de presentación que se ha relacionado con un diagnóstico más precoz de la enfermedad (p<0,05). En el estudio ecográfico 10 pacientes presentaron hipertrofia ventricular, relacionándose con enfermedad mitocondrial y lisosomal; sólo 2 pacientes presentaron dilatación ventricular, que se relaciona con alteración del metabolismo de los ácidos grasos (p<0,05). La supervivencia mediana fue de 5 meses (rango, 2-11 meses). Ninguna variable se ha relacionado de forma estadísticamente significativa con la probabilidad de fallecer. Conclusiones:Los pacientes que comienzan en forma de descompensación cardiaca se diagnostican más precozmente. La ecocardiografía orienta en el diagnóstico etiológico y en el seguimiento de la enfermedad metabólica (AU)

Background and objective: Cardiomyopathy in childhood is a rare entity. Inborn errors of metabolism can cause myocardial involvement by several mechanisms. Patients and methods: Patients under 16 years diagnosed with cardiomyopathy and EIM in a period of 11 years (1998-2009) were included. Results: A total of 12 patients were studied (8% of all cardiomyopathies), 9 boys and three girls, with a median age at diagnosis of 6 months (range: birth-8.8 years). Fifty percent had an onset with cardiac symptoms and heart failure was associated with an earlier diagnosis of the disease (P<.05). On ultrasound 10 patients had ventricular hypertrophy, which was associated with mitochondrial and lysosomal disease; only 2 patients had ventricular dilatation, which was associated with altered fatty acid metabolism (P<.05). The median survival was 5 months (range: 2-11 months). No variable was significantly associated with the likelihood of death. Conclusions: Patients with heart failure at onset are diagnosed earlier (before 3 months of life). Echocardiography helps in the diagnosis and monitoring of metabolic disease (AU)

[Cardiomyopathy and inborn errors of metabolism in children. Study of 12 cases]. / Miocardiopatía en niños con errores innatos del metabolismo: descripción de 12 casos.

BACKGROUND AND OBJECTIVE: Cardiomyopathy in childhood is a rare entity. Inborn errors of metabolism can cause myocardial involvement by several mechanisms. PATIENTS AND METHODS: Patients under 16 years diagnosed with cardiomyopathy and EIM in a period of 11 years (1998-2009) were included. RESULTS: A total of 12 patients were studied (8% of all cardiomyopathies), 9 boys and three girls, with a median age at diagnosis of 6 months (range: birth-8.8 years). Fifty percent had an onset with cardiac symptoms and heart failure was associated with an earlier diagnosis of the disease (P<.05). On ultrasound 10 patients had ventricular hypertrophy, which was associated with mitochondrial and lysosomal disease; only 2 patients had ventricular dilatation, which was associated with altered fatty acid metabolism (P<.05). The median survival was 5 months (range: 2-11 months). No variable was significantly associated with the likelihood of death. CONCLUSIONS: Patients with heart failure at onset are diagnosed earlier (before 3 months of life). Echocardiography helps in the diagnosis and monitoring of metabolic disease.