[The metabolic newborn screening as a healthcare model of the precision medicine. Perspective from the Spanish Association for the Study of Congenital Errors of Metabolism (AECOM).] / El cribado metabólico del recién nacido como modelo asistencial de la medicina de precisión. Perspectiva desde la Asociación Española para el Estudio de los Errores Congénitos del Metabolismo (AECOM).

Newborn screening programs for congenital diseases aim to achieve a presymptomatic and early diagnosis of treatable disorders, in order to prevent or significantly reduce morbidity and/or mortality. Many of the conditions included in these programs are inborn errors of metabolism (IEM); however, the detection of endocrine, hematological, immunological, cardiovascular diseases, and congenital hearing loss are also included in many of them. Newborn screening tests are not diagnostic and therefore additional tests are needed to confirm or exclude the suspected diagnosis. The social and professional demand of the hand of the technological advances and new therapeutic options, allow the continuous expansion of neonatal screening; This progress has a clear benefit for patients, since thanks to the early diagnosis and treatment of their disease they can have a better prognosis and a better quality of life. The inclusion criteria of the different diseases should not be evaluated exclusively in function of the moment in which the evaluation is carried out, it is necessary to apply a long-term vision of opportunity based on the strengths of the health system. Today, after 50 years of experience, we can assure that neonatal screening programs constitute one of the most significant advances that have occurred in public health, their widespread practice has been one of the great achievements in pediatric healthcare and are marking the healthcare organization of many adult units. Hand in hand with advances in genetics and genomics, newborn screening programs will continue to expand for those disorders in which early intervention can significantly modify the course of the disease.

Los programas de cribado de enfermedades congénitas en los recién nacidos tienen como objetivo lograr un diagnóstico presintomático y temprano de trastornos tratables, con el fin de prevenir o reducir significativamente la morbilidad y/o mortalidad. Muchas de las condiciones incluidas en es estos programas son errores innatos del metabolismo (EIM); sin embargo, la detección de enfermedades endocrinas, hematológicas, inmunológicas, cardiovasculares, y la hipoacusia congénita también se incluyen en muchos de ellos. Las pruebas de detección de recién nacidos no son diagnósticas y, por tanto, se necesitan pruebas complementarias para confirmar o excluir la sospecha diagnóstica. La demanda social y profesional de la mano de los avances tecnológicos y de nuevas opciones de tratamiento, permiten la expansión continua del cribado neonatal; este progreso conlleva un claro beneficio para los pacientes, pues gracias al diagnóstico y al tratamiento precoz de su enfermedad pueden tener un mejor pronóstico y una mejor calidad de vida. Los criterios de inclusión de las diferentes enfermedades no deben ser valorados exclusivamente con el prisma del momento en que se realiza la evaluación, es necesario aplicar una visión de oportunidad a largo plazo basada en las fortalezas del sistema sanitario. Hoy en día, tras 50 años de recorrido, podemos asegurar que los programas de cribado neonatal constituyen uno de los avances más significativos que se han producido en salud pública, su práctica generalizada ha significado uno de los grandes logros asistenciales en pediatría y están marcando la organización asistencial de muchas unidades de adultos. De la mano de los avances en genética y genómica, los programas de cribado del recién nacido continuarán expandiéndose para aquellos trastornos en los que una intervención temprana pueda modificar significativamente el curso de la enfermedad.

Urine Phenylacetylglutamine Determination in Patients with Hyperphenylalaninemia.

Phenylketonuria (PKU), an autosomal-recessive inborn error of phenylalanine (Phe) metabolism is the most prevalent disorder of amino acid metabolism. Currently, clinical follow-up relies on frequent monitoring of Phe levels in blood. We hypothesize that the urine level of phenylacetylglutamine (PAG), a phenyl-group marker, could be used as a non-invasive biomarker. In this cross-sectional study, a validated liquid chromatography coupled to tandem mass spectrometry (LC-MS) method was used for urinary PAG quantification in 35 participants with hyperphenylalaninemia (HPA) and 33 age- and sex-matched healthy controls. We have found that (a) PKU patients present higher urine PAG levels than healthy control subjects, and that (b) there is a significant correlation between urine PAG and circulating Phe levels in patients with HPA. In addition, we show a significant strong correlation between Phe levels from venous blood samples and from capillary finger-prick dried blood spot (DBS) samples collected at the same time in patients with HPA. Further research in order to assess the potential role of urine PAG as a non-invasive biomarker in PKU is warranted.

Leigh syndrome associated with TRMU gene mutations.

tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) deficiency causes an early onset potentially reversible acute liver failure, so far reported in less than 30 patients. We describe two new unrelated patients with an acute liver failure and a neuroimaging compatible with Leigh syndrome (LS) due to TRMU deficiency, a combination not previously reported. Our report enlarges the phenotypical spectrum of TRMU disease.

Transferrin Isoforms, Old but New Biomarkers in Hereditary Fructose Intolerance.

Hereditary Fructose Intolerance (HFI) is an autosomal recessive inborn error of metabolism characterised by the deficiency of the hepatic enzyme aldolase B. Its treatment consists in adopting a fructose-, sucrose-, and sorbitol (FSS)-restrictive diet for life. Untreated HFI patients present an abnormal transferrin (Tf) glycosylation pattern due to the inhibition of mannose-6-phosphate isomerase by fructose-1-phosphate. Hence, elevated serum carbohydrate-deficient Tf (CDT) may allow the prompt detection of HFI. The CDT values improve when an FSS-restrictive diet is followed; however, previous data on CDT and fructose intake correlation are inconsistent. Therefore, we examined the complete serum sialoTf profile and correlated it with FSS dietary intake and with hepatic parameters in a cohort of paediatric and adult fructosemic patients. To do so, the profiles of serum sialoTf from genetically diagnosed HFI patients on an FSS-restricted diet (n = 37) and their age-, sex- and body mass index-paired controls (n = 32) were analysed by capillary zone electrophoresis. We found that in HFI patients, asialoTf correlated with dietary intake of sucrose (R = 0.575, p < 0.001) and FSS (R = 0.475, p = 0.008), and that pentasialoTf+hexasialoTf negatively correlated with dietary intake of fructose (R = -0.386, p = 0.024) and FSS (R = -0.400, p = 0.019). In addition, the tetrasialoTf/disialoTf ratio truthfully differentiated treated HFI patients from healthy controls, with an area under the ROC curve (AUROC) of 0.97, 92% sensitivity, 94% specificity and 93% accuracy.

Importance of Timely Treatment Initiation in Infantile-Onset Pompe Disease, a Single-Centre Experience.

Classic infantile Pompe disease (IPD) is a rare lysosomal storage disorder characterized by severe hypertrophic cardiomyopathy and profound muscle weakness. Without treatment, death occurs within the first 2 years of life. Although enzyme replacement therapy (ERT) with alglucosidase alfa has improved survival, treatment outcome is not good in many cases and is largely dependent on age at initiation. The objective of the study was (a) to analyse the different stages in the diagnosis and specific treatment initiation procedure in IPD patients, and (b) to compare clinical and biochemical outcomes depending on age at ERT initiation (<1 month of age vs. <3 months of age). Here, we show satisfactory clinical and biochemical outcomes in two IPD patients after early treatment initiation before 3 months of life with immunomodulatory therapy in the ERT-naïve setting, with a high ERT dose from the beginning. Despite the overall good evolution, the patient who initiated treatment <1 month of life presented even better outcomes than the patient who started treatment <3 months of life, with an earlier normalization of hypertrophic cardiomyopathy, along with CK normalization, highlighting the importance of early treatment initiation in this progressive disease before irreversible muscle damage has occurred.