Clinical Utility of LCT Genotyping in Children with Suspected Functional Gastrointestinal Disorder

Genetic testing is a good predictor of lactase persistence (LP) in specific populations but its clinical utility in children is less clear. We assessed the role of lactose malabsorption in functional gastrointestinal disorders (FGID) in children and the correlation between the lactase non-persistence (LNP) genotype and phenotype, based on exhaled hydrogen and gastrointestinal symptoms, during a hydrogen breath test (HBT). We also evaluate dairy consumption in this sample. We conducted a 10-year cross-sectional study in a cohort of 493 children with suspected FGID defined by Roma IV criteria. Distribution of the C/T-13910 genotype was as follows: CC, 46.0%; TT, 14.4% (LP allele frequency, 34.1%). The phenotype frequencies of lactose malabsorption and intolerance were 36.3% and 41.5%, respectively. We observed a strong correlation between genotype and both lactose malabsorption (Cramér’s V, 0.28) and intolerance (Cramér’s V, 0.54). The frequency of the LNP genotype (p = 0.002) and of malabsorption and intolerance increased with age (p = 0.001 and 0.002, respectively). In 61% of children, evaluated dairy consumption was less than recommended. No association was observed between dairy intake and diagnosis. In conclusion, we found a significant correlation between genotype and phenotype, greater in older children, suggesting that the clinical value of genetic testing increases with ageS

Similarities between acylcarnitine profiles in large for gestational age newborns and obesity

Large for gestational age (LGA) newborns have an increased risk of obesity, insulin resistance, and metabolic syndrome. Acylcarnitine profiles in obese children and adults are characterized by increased levels of C3, C5, and certain medium-chain (C12) and long-chain (C14:1 and C16) acylcarnitines. C2 is also increased in insulin-resistant states. In this 1-year observational study of 2514 newborns (246 LGA newborns, 250 small for gestational age (GA) newborns, and 2018 appropriate for GA newborns), we analyzed and compared postnatal acylcarnitine profiles in LGA newborns with profiles described for obese individuals. Acylcarnitine analysis was performed by tandem mass spectrometry on dried-blood spots collected on day 3 of life. LGA newborns had higher levels of total short-chain acylcarnitines (p < 0.001), C2 (p < 0.01) and C3 (p < 0.001) acylcarnitines, and all C12, C14, and C16 acylcarnitines except C12:1. They also had a higher tendency towards carnitine insufficiency (p < 0.05) and carnitine deficiency (p < 0.001). No significant differences were observed between LGA newborns born to mothers with or without a history of gestational diabetes. This novel study describes a postnatal acylcarnitine profile in LGA with higher levels of C2, C3, total acylcarnitines, and total short-chain acylcarnitines that is characteristic of childhood and adult obesity and linked to an unhealthy metabolic phenotype.Dr Lopez has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 281854 -the ObERStress project, Xunta de Galicia (2015-CP079 and 2016-PG068), MINECO co-funded by FEDER (SAF2015-71026-R and BFU2015-70454-REDT/Adipoplast)S

Identification of a Novel Variant in EARS2 Associated with a Severe Clinical Phenotype Expands the Clinical Spectrum of LTBL

The EARS2 nuclear gene encodes mitochondrial glutamyl-tRNA synthetase, a member of the class I family of aminoacyl-tRNA synthetases (aaRSs) that plays a crucial role in mitochondrial protein biosynthesis by catalyzing the charging of glutamate to mitochondrial tRNA(Glu). Pathogenic EARS2 variants have been associated with a rare mitochondrial disorder known as leukoencephalopathy with thalamus and brainstem involvement and high lactate (LTBL). The targeted sequencing of 150 nuclear genes encoding respiratory chain complex subunits and proteins implicated in the oxidative phosphorylation (OXPHOS) function was performed. The oxygen consumption rate (OCR), and the extracellular acidification rate (ECAR), were measured. The enzymatic activities of Complexes I-V were analyzed spectrophotometrically. We describe a patient carrying two heterozygous EARS2 variants, c.376C>T (p.Gln126*) and c.670G>A (p.Gly224Ser), with infantile-onset disease and a severe clinical presentation. We demonstrate a clear defect in mitochondrial function in the patient’s fibroblasts, suggesting the molecular mechanism underlying the pathogenicity of these EARS2 variants. Experimental validation using patient-derived fibroblasts allowed an accurate characterization of the disease-causing variants, and by comparing our patient’s clinical presentation with that of previously reported cases, new clinical and radiological features of LTBL were identified, expanding the clinical spectrum of this diseaseThis study was supported with a competitive PhD grant from a pre-Doctoral scholarship for research groups of the Health Research Institute of Santiago (IDIS)S

V232D Mutation in Patients With Cystic Fibrosis: Not So Rare, Not So Mild

The frequency of some Cystic Fibrosis (CF) Transmembrane Conductance Regulator gene (CFTR) mutations varies between populations. Genetic testing during newborn screening (NBS) for CF can identify less common mutations with low clinical expression in childhood and previously considered mild but not fully characterized, such as the mutation p.Val232Asp (c.695T > A). The aim of this study was to describe CF patients with the V232D mutation. We identify CF children with the V232D mutation detected by NBS and compare them with CF adults with this mutation whose diagnosis was prompted by clinical symptoms in the same period. We studied clinical, biochemical, spirometric, and prognostic features in both populations. NBS program tested 276,523 children during a period of 14 years (2003-2017) and identified 54 cases of CF. Six children (11%) had the V232D mutation. Over the same period, 5 adults (age 37.6 ± 16.29 years old) with symptoms of CF and this mutation were also diagnosed. Follow-up duration was mean 10.1 years for adults and mean 6.5 years for children. In the adult group, lung function was impaired at diagnosis in all patients (Forced Expiratory Volume1-FEV1-67.12% ± 13.09) and worsened in children tested during evolution (FEV1first: 113%; FEV1last: 64%). Pancreatic insufficiency was present in adult group, with recurrent pancreatitis in 1 present. Although with less clinical expression in children, V232D is associated with pulmonary and pancreatic involvement during adulthood and CF cannot be considered mild. This mutation is present in 11% of all patients diagnosed with CF in our region. Its inclusion in some NBS programs should be taken into account in order to improve the prognosis of affected children.S

Newborn screening for Fabry disease in the north-west of Spain

Fabry disease is an X-linked lysosomal storage disorder caused by the impairment of α-galactosidase A. Enzyme replacement therapy is available to treat patients, who often experience delayed diagnosis. A newborn screening for Fabry disease was performed to study the prevalence of the pathology and to evaluate the possibility to implement the test in systematic screenings. We collected 14,600 dried blood spot samples (7575 males and 7025 females) and carried out a diagnostic study by fluorometric measurement of α-galactosidase A enzymatic activity and GLA gene sequencing. We detected one patient with a mutation in GLA associated with classical Fabry Disease (M290I), ten subjects carrying genetic variants of uncertain diagnosis (S126G, R118C, A143T), and a girl with the non-characterized variant F18Y, which was not previously described. Additional 25 samples presented nucleotide substitutions described as polymorphisms (D313Y, rs2071225, and rs2071397). The estimated prevalence for Fabry disease in north-western Spanish males is of 0.013%. Conclusion: These results confirm that the prevalence of Fabry disease is underestimated and systematic screening is feasible; however, further characterization of variants of uncertain clinical significance is necessary to establish protocols of patients’ managementThis studied was founded by the Spanish National Institute of Health-Instituto Carlos III/EU-FEDER, grant no. PI11-00842, to Ortolano S. and FEEL Foundation to Cristobal ColónS

Proteomic analysis in morquio a cells treated with immobilized enzymatic replacement therapy on nanostructured lipid systems

[ENG]Morquio A syndrome, or mucopolysaccharidosis type IVA (MPS IVA), is a lysosomal storage disease due to mutations in the N-acetylgalactosamine-6-sulfatase (GALNS) gene. Systemic skeletal dysplasia and the related clinical features of MPS IVA are due to disruption of cartilage and its extracellular matrix, leading to an imbalance of growth. Enzyme replacement therapy (ERT) with recombinant human GALNS, alpha elosulfase, provides a systemic treatment. However, this therapy has a limited impact on skeletal dysplasia because the infused enzyme cannot penetrate cartilage and bone. Therefore, an alternative therapeutic approach to reach the cartilage is an unmet challenge. We have developed a new drug delivery system based on a nanostructure lipid carrier with the capacity to immobilize enzymes used for ERT and to target the lysosomes. This study aimed to assess the effect of the encapsulated enzyme in this new delivery system, using in vitro proteomic technology. We found a greater internalization of the enzyme carried by nanoparticles inside the cells and an improvement of cellular protein routes previously impaired by the disease, compared with conventional ERT. This is the first qualitative and quantitative proteomic assay that demonstrates the advantages of a new delivery system to improve the MPS IVA ERTS

Identification and Characterization of New Variants in FOXRED1 Gene Expands the Clinical Spectrum Associated with Mitochondrial Complex I Deficiency

Complex I (nicotinamide adenine dinucleotide (NADH): ubiquinone oxidoreductase) is the largest complex of the mitochondrial oxidative phosphorylation system (OXPHOS) system. Forty-four subunits encoded in nuclear and mitochondrial genomes compose this multiprotein complex, its assembly being a highly complex process involving at least 15 additional nuclear encoded assembly factors. Complex I deficiency is a mitochondrial disorder usually associated with early-onset severe multisystem disorders characterized by highly variable clinical manifestations. Flavin adenine dinucleotide (FAD)-dependent oxidoreductase domain-containing protein 1 (FOXRED1) is a complex I assembly factor. To date, only five patients with mitochondrial complex I deficiency due to mutations in FOXRED1 have been characterized. Here, we describe a child with ataxia, epilepsy and psychomotor developmental delay carrying two heterozygous FOXRED1 variants, c.920G>A (p.Gly307Glu) and c.733+1G>A. We demonstrate the molecular mechanism supporting the pathogenicity of the FOXRED1 variants, showing a clear deficiency of complex I activity. The reduction in the steady-state level of complex I holoenzyme in patient fibroblasts, confirmed the pathogenicity of the variants and showed the molecular mechanism behind their pathogenicity. A comparison of the clinical presentation of the index case with the previously described cases allowed deepening our knowledge about the clinical variability associated with FOXRED1 defectsThis study was supported with a competitive Ph.D. grant by Pre-Doctoral scholarship, for research groups of the Health Research Institute of Santiago (IDIS)S

Characterization of New Proteomic Biomarker Candidates in Mucopolysaccharidosis Type IVA

Mucopolysaccharidosis type IVA (MPS IVA) is a lysosomal storage disease caused by mutations in the N-acetylgalactosamine-6-sulfatase (GALNS) gene. Skeletal dysplasia and the related clinical features of MPS IVA are caused by disruption of the cartilage and its extracellular matrix, leading to a growth imbalance. Enzyme replacement therapy (ERT) with recombinant human GALNS has yielded positive results in activity of daily living and endurance tests. However, no data have demonstrated improvements in bone lesions and bone grow thin MPS IVA after ERT, and there is no correlation between therapeutic efficacy and urine levels of keratan sulfate, which accumulates in MPS IVA patients. Using qualitative and quantitative proteomics approaches, we analyzed leukocyte samples from healthy controls (n = 6) and from untreated (n = 5) and ERT-treated (n = 8, sampled before and after treatment) MPS IVA patients to identify potential biomarkers of disease. Out of 690 proteins identified in leukocytes, we selected a group of proteins that were dysregulated in MPS IVA patients with ERT. From these, we identified four potential protein biomarkers, all of which may influence bone and cartilage metabolism: lactotransferrin, coronin 1A, neutral alpha-glucosidase AB, and vitronectin. Further studies of cartilage and bone alterations in MPS IVA will be required to verify the validity of these proteins as potential biomarkers of MPS IVAS

Enzyme-Loaded Gel Core Nanostructured Lipid Carriers to Improve Treatment of Lysosomal Storage Diseases: Formulation and In Vitro Cellular Studies of Elosulfase Alfa-Loaded Systems

Mucopolysaccharidosis IVA (Morquio A) is a rare inherited metabolic disease caused by deficiency of the lysosomal enzyme N-acetylgalatosamine-6-sulfate-sulfatase (GALNS). Until now, treatments employed included hematopoietic stem cell transplantation and enzyme replacement therapy (ERT); the latter being the most commonly used to treat mucopolysaccharidoses, but with serious disadvantages due to rapid degradation and clearance. The purpose of this study was to develop and evaluate the potential of nanostructured lipid carriers (NLCs) by encapsulating elosulfase alfa and preserving its enzyme activity, leading to enhancement of its biological effect in chondrocyte cells. A pegylated elosulfase alfa-loaded NLC was characterized in terms of size, ζ potential, structural lipid composition (DSC and XRD), morphology (TEM microscopy), and stability in human plasma. The final formulation was freeze-dried by selecting the appropriate cryoprotective agent. Viability assays confirmed that NLCs were non-cytotoxic to human fibroblasts. Imaging techniques (confocal and TEM) were used to assess the cellular uptake of NLCs loaded with elosulfase alfa. This study provides evidence that the encapsulated drug exhibits enzyme activity inside the cells. Overall, this study provides a new approach regarding NLCs as a promising delivery system for the encapsulation of elosulfase alfa or other enzymes and the preservation of its activity and stability to be used in enzymatic replacement therapy (ERT).This research was funded by Xunta de Galicia, grant number GRC2013/015 and GPC2017/015S

Diagnóstico precoz de los errores congénitos del metabolismo

Los avances científicos recientes han permitido identificar un número importante de enfermedades consideradas como raras, aquellas que tienen una baja prevalencia o aparecen ocasionalmente en la población &ndash;en Europa, menos de 1 caso cada 2.000 ciudadanos&ndash;, entre las que se encuentran las enfermedades metabólicas. En España, se estima que hay, aproximadamente, tres millones de afectados por estas dolencias, cuya atención está siendo objeto de interés por las administraciones sanitarias. Las enfermedades metabólicas, o errores congénitos del metabolismo (ECM), son un grupo numeroso de dolencias hereditarias, cada una producida por el bloqueo de alguna vía metabólica en el organismo. La mayoría de ellas se heredan de forma autosómica recesiva, y su frecuencia se estima entre 1/1.000-3.000 recién nacidos vivos. Esta memoria recoge las investigaciones y trabajos llevados a cabo en la Unidad de Diagnóstico y Tratamiento de los Errores Congénitos del Metabolismo (UDTECM), del Departamento de Pediatría del Hospital Clínico Universitario de Santiago de Compostela, dedicado a evitar enfermedades que supongan un riesgo para el pleno desarrollo del recién nacido. En ella se presentan los resultados globales del programa de diagnóstico precoz neonatal desarrollado durante más de 30 años, del que se han beneficiado cerca de 700.000 niños. La unidad, formada por un equipo multiprofesional, ha recibido el Premio Reina Sofía 2008, de Prevención de la Discapacidad