Impact of Structural GLA Protein Changes on Peripheral GLA Activity and Substrate Accumulation in Fabry Disease Patients.

INTRODUCTION: Fabry disease is an X-linked lysosomal storage disorder caused by pathogenic variants in the GLA gene, leading to decreased/absent α-galactosidase activity. In clinical practice, enzyme activity and substrate/byproduct accumulation play a role in diagnosis and disease-monitoring biomarkers. However, interpreting biomarker levels is not straightforward and can change according to the underlying GLA protein abnormality. OBJECTIVE: Our goals were to understand how disrupting specific protein regions changes biomarker behaviour and to establish specific patterns for individual variants. METHODOLOGY: We analysed data from the Biochemical Genetics Laboratory regarding GLA variants, GLA enzyme activity (in dried blood spots, plasma or white blood cells), plasma LysoGb3 accumulation, and urinary Gb3 excretion. We assessed correlations, trends, and potential predictor models of biomarker behaviour. RESULTS: We assessed 169 hemizygous male and 255 heterozygous female patients. For both groups, substrate accumulation correlates inversely with GLA activity. Variants affecting residues buried within the protein core or the active site were associated with more severe biomarker changes, while those affecting residues that establish disulfide bonds or are glycosylated were similar to other variants. For each non-truncating variant, we also established specific profiles of biomarker behaviour. Finally, we also designed predictor models of biomarker behaviour based on structural variant information. This study provides the groundwork for the impact of GLA protein variation on GLA activity and substrate accumulation. CONCLUSION: This knowledge is of extreme relevance for diagnostic labs and clinicians, as some genetic variants are challenging to interpret regarding pathogenicity. Assessing whether biomarker changes are in the expected range for a specific variant may help diagnostic evaluation. This study also contributes to recognising non-disease-causing variants, considering their overall biochemical impact, and providing a comparative reference for biomarker discovery studies. In the future, the correlation of these findings with disease severity may be of great relevance for diagnosis and monitoring progression.

Amino Acid Profiles in the Biological Fluids and Tumor Tissue of CRC Patients.

Amino acids are the building blocks of proteins and essential players in pathways such as the citric acid and urea cycle, purine and pyrimidine biosynthesis, and redox cell signaling. Therefore, it is unsurprising that these molecules have a significant role in cancer metabolism and its metabolic plasticity. As one of the most prevalent malign diseases, colorectal cancer needs biomarkers for its early detection, prognostic, and prediction of response to therapy. However, the available biomarkers for this disease must be more powerful and present several drawbacks, such as high costs and complex laboratory procedures. Metabolomics has gathered substantial attention in the past two decades as a screening platform to study new metabolites, partly due to the development of techniques, such as mass spectrometry or liquid chromatography, which have become standard practice in diagnostic procedures for other diseases. Extensive metabolomic studies have been performed in colorectal cancer (CRC) patients in the past years, and several exciting results concerning amino acid metabolism have been found. This review aims to gather and present findings concerning alterations in the amino acid plasma pool of colorectal cancer patients.

NPC1 silent variant induces skipping of exon 11 (p.V562V) and unfolded protein response was found in a specific Niemann-Pick type C patient.

BACKGROUND: Niemann-Pick type C (NPC, MIM #257220) is a neuro-visceral disease, caused predominantly by pathogenic variants in the NPC1 gene. Here we studied patients with clinical diagnosis of NPC but inconclusive results regarding the molecular analysis. METHODS: We used a Next-Generation Sequencing (NGS)-panel followed by cDNA analysis. Latter, we used massively parallel single-cell RNA-seq (MARS-Seq) to address gene profiling changes and finally the effect of different variants on the protein and cellular levels. RESULTS: We identified novel variants and cDNA analysis allowed us to establish the functional effect of a silent variant, previously reported as a polymorphism. We demonstrated that this variant induces the skipping of exon 11 leading to a premature stop codon and identified it in NPC patients from two unrelated families. MARS-Seq analysis showed that a number of upregulated genes were related to the unfolded protein response (UPR) and endoplasmic reticulum (ER) stress in one specific patient. Also, for all analyzed variants, the NPC1 protein was partially retained in the ER. CONCLUSION: We showed that the NPC1 silent polymorphism (p.V562V) is a disease-causing variant in NPC and that the UPR is upregulated in an NPC patient.

Molecular characterization of a large group of Mucopolysaccharidosis type IIIC patients reveals the evolutionary history of the disease.

Mucopolysaccharidosis type IIIC (MPSIIIC) is a severe, rare autosomal recessive disorder caused by variants in the heparan-α-glucosaminide N-acetyltransferase (HGSNAT) gene which result in lysosomal accumulation of heparan sulfate. We analyzed clinical presentation, molecular defects and their haplotype context in 78 (27 novel) MPSIIIC cases from 22 countries, the largest group studied so far. We describe for the first time disease-causing variants in the patients from Brazil, Algeria, Azerbaijan, and Iran, and extend their spectrum within Canada, Colombia, Turkey, and the USA. Six variants are novel: two missense, c.773A>T/p.N258I and c.1267G>T/p.G423W, a nonsense c.164T>A/p.L55*, a splice-site mutation c.494-1G>A/p.[P165_L187delinsQSCYVTQAGVRWHHLGSLQALPPGFTPFSYLSLLSSWNC,P165fs], a deletion c.1348delG/p.(D450fs) and an insertion c.1479dupA/p.(Leu494fs). The missense HGSNAT variants lacked lysosomal targeting, enzymatic activity, and likely the correct folding. The haplotype analysis identified founder mutations, p.N258I, c.525dupT, and p.L55* in the Brazilian state of Paraiba, c.493+1G>A in Eastern Canada/Quebec, p.A489E in the USA, p.R384* in Poland, p.R344C and p.S518F in the Netherlands and suggested that variants c.525dupT, c.372-2G>A, and c.234+1G>A present in cis with c.564-98T>C and c.710C>A rare single-nucleotide polymorphisms, have been introduced by Portuguese settlers in Brazil. Altogether, our results provide insights into the origin, migration roots and founder effects of HGSNAT disease-causing variants, and reveal the evolutionary history of MPSIIIC.

Genotype-phenotype correlations and BH4 estimated responsiveness in patients with phenylketonuria from Rio de Janeiro, Southeast Brazil.

BACKGROUND: Genetic heterogeneity and compound heterozygosis give rise to a continuous spectrum of phenylalanine hydroxylase deficiency and metabolic phenotypes in phenylketonuria (PKU). The most used parameters for evaluating phenotype in PKU are pretreatment phenylalanine (Phe) levels, tolerance for dietary Phe, and Phe overloading test. Phenotype can vary from a "classic" (severe) form to mild hyperphenylalaninemia, which does not require dietary treatment. A subset of patients is responsive to treatment by the cofactor tetrahydrobiopterin (BH4 ). Genotypes of PKU patients from Rio de Janeiro, Brazil, were compared to predicted and observed phenotypes. Genotype-based estimations of responsiveness to BH4 were also conducted. METHODS: Phenotype was defined by pretreatment Phe levels. A standard prediction system based on arbitrary assigned values was employed to measure genotype-phenotype concordance. Patients were also estimated as BH4 -responders according to the responsiveness previously reported for their mutations and genotypes. RESULTS: A 48.3% concordance rate between genotype-predicted and observed phenotypes was found. When the predicted phenotypes included those reported at the BIOPKU database, the concordance rate reached 77%. A total of 18 genotypes from 30 patients (29.4%) were estimated as of potential or probable BH4 responsiveness. Inconsistencies were observed in genotypic combinations including the common "moderate" mutations p.R261Q, p.V388M, and p.I65T and the mild mutations p.L48S, p.R68S, and p.L249F. CONCLUSION: The high discordance rate between genotype-predicted and observed metabolic phenotypes in this study seems to be due partially to the high frequency of the so-called "moderate" common mutations, p.R261Q, p.V388M, and p.I65T, which are reported to be associated to erratic or more severe than expected metabolic phenotypes. Although our results of BH4 estimated responsiveness must be regarded as tentative, it should be emphasized that genotyping and genotype-phenotype association studies are important in selecting patients to be offered a BH4 overload test, especially in low-resource settings like Brazil.

Orientações do enfermeiro aos idosos com diabetes mellitus: prevenindo lesões / Nurse orientations to the elderly with diabetes mellitus: preventing injury

Objetivo: analisar as orientações dos enfermeiros da Unidades de Saúde da Família aos idosos com Diabetes Mellitus na prevenção de lesões na pele. Método: trata-se de um estudo qualitativo, descritivo, exploratório, com sete enfermeiros, por meio de uma entrevista, utilizando um instrumento semiestruturado, e para a análise, empregou-se a técnica de Análise de Conteúdo na modalidade Análise Categorial. Resultados: evidenciou-se que existem déficits quanto ao método de avaliação e orientação aos cuidados de lesão na pele durante as consultas de Enfermagem como, também, estratégias de envolvimento do familiar na participação desse cuidado na descrição das categorias. Conclusão: entende-se que o enfermeiro precisa ter um bom conhecimento teórico-prático para que, junto com a família e a equipe multiprofissional, venha promover o cuidado que é devido a esses pacientes, intervindo positivamente e diminuindo o risco de desenvolvimento de lesões e problemas na pele.(AU)

Objective: to analyze the guidelines of the Nurses of the Family Health Units to the elderly with Diabetes Mellitus in the prevention of skin lesions. Method: it is a qualitative, descriptive, exploratory study with seven nurses, through an interview, using a semi-structured instrument, and for the analysis, the technique of Content Analysis was used in the category Categorical Analysis. Results: it was evidenced that there are deficits regarding the method of evaluation and orientation to the care of skin lesions during Nursing consultations as well as strategies of involvement of the family in the participation of this care in the description of the categories. Conclusion: it is understood that the nurse needs to have a good theoretical-practical knowledge so that, together with the family and the multiprofessional team, it can promote the care that is due to these patients, intervening positively and reducing the risk of developing lesions and skin problems.(AU)

Objetivo: analizar las orientaciones de los enfermeros de las Unidades de Salud de la Familia para ancianos con Diabetes Mellitus en la prevención de lesiones cutáneas. Método: se trata de un estudio cualitativo, descriptivo, exploratorio con siete enfermeros, a través de una entrevista, utilizando un instrumento semiestructurado y, para el análisis, se utilizó la técnica de Análisis de Contenido en la modalidad de Análisis categórico. Resultados: se evidenció que existen deficiencias en cuanto al método de evaluación y orientación a los cuidados de lesiones cutáneas durante las consultas de enfermería, así como a las estrategias de involucración de la familia en la participación de este cuidado en la descripción de las categorías. Conclusión: se entiende que el enfermero necesita tener un buen conocimiento teórico y práctico de modo que, junto con la familia y el equipo multiprofesinal, venga promover el cuidado que se debe a estos pacientes, interviniendo positivamente y disminuyendo el riesgo de desarrollo de lesiones y problemas en la piel.(AU)

Mutation analysis of the PAH gene in phenylketonuria patients from Rio de Janeiro, Southeast Brazil.

BACKGROUND: Phenylketonuria (PKU) is an autosomal recessive disease resulting from mutations in the PAH gene. Most of the patients are compound heterozygotes, and genotype is a major factor in determining the phenotypic variability of PKU. More than 1,000 variants have been described in the PAH gene. Rio de Janeiro's population has a predominance of Iberian, followed by African and Amerindian ancestries. It is expected that most PKU variants in this Brazilian state have originated in the Iberian Peninsula. However, rare European, African or pathogenic variants that are characteristic of the admixed population of the state might also be found. METHODS: A total of 102 patients were included in this study. Genomic DNA was isolated from dried blood spots. Sanger sequencing was used for PAH gene variant identification. Deletions and duplications were also screened using MLPA analysis. Haplotypes were also determined. RESULTS: Nine (8.8%) homozygous and 93 (91.2%) compound heterozygous patients were found. The spectrum included 37 causative mutations. Missense, nonsense, and splicing pathogenic variants corresponded to 63.7%, 2.9%, and 22.6% of the mutant alleles, respectively. Large (1.5%), and small deletions, inframe (5.4%) and with frameshift (3.9%), comprised the remainder. The most frequent pathogenic variants were: p.V388M (12.7%), p.R261Q (11.8%), IVS10-11G>A (10.3%), IVS2+5G>C (6.4%), p.S349P (6.4%), p.R252W (5.4%), p.I65T (4.4%), p.T323del (4.4%), and p.P281L (3.4%). One novel variant was detected: c.934G>T (p.G312C) [rs763115697]. CONCLUSION: The three most frequent pathogenic variants in our study (34.8% of the alleles) were also the most common in other Brazilian states, Portugal, and Spain (p.V388M, p.R261Q, IVS10-11G>A), corroborating that the Iberian Peninsula is the major source of PAH mutations in Rio de Janeiro. Pathogenic variants that have other geographical origins, such IVS2+5G>C, p.G352Vfs*48, and IVS12+1G>A were also detected. Genetic drift and founder effect may have also played a role in the mutation spectrum we observed.

Screening for Pompe disease in a Portuguese high risk population.

Pompe disease is a rare metabolic disorder with available enzymatic replacement therapy. Contrasting with the classic infantile form, the others subtypes have a heterogeneous presentation that makes an early and accurate diagnosis difficult. We conducted a prospective, multicenter, observational study to identify undiagnosed patients. During a one-year period, patients followed in Portuguese neuromuscular outpatient clinics with proximal muscle weakness affecting upper and/or lower limbs, hyperCKemia in two or more determinations or hypotonia and hyperCKemia, were screened for acid α-glucosidase deficiency by dried blood spots. Lysosomal acid-alpha-1,4-glucosidase activity was determined by tandem mass spectrometry and positive results were confirmed by molecular study. From the 99 patients screened, Pompe disease was confirmed in 4, with age of onset ranging from 2.5 to 48 years, all with limb girdle muscle weakness, corresponding to a frequency of 4% in our cohort and 4.9% of limb girdle muscle weakness. Screening for Pompe disease in high risk populations, using dried blood spots, was already performed in some European populations. Apart from two negative Scandinavian studies, positive cases were confirmed in 2.8-7.9% of patients presenting with limb girdle muscle weakness and in 0-2.5% with isolated hyperCKemia.

Solving a case of allelic dropout in the GNPTAB gene: implications in the molecular diagnosis of mucolipidosis type III alpha/beta.

While being well known that the diagnosis of many genetic disorders relies on a combination of clinical suspicion and confirmatory genetic testing, not rarely, however, genetic testing needs much perseverance and cunning strategies to identify the causative mutation(s). Here we present a case of a thorny molecular diagnosis of mucolipidosis type III alpha/beta, which is an autosomal recessive lysosomal storage disorder, caused by a defect in the GNPTAB gene that codes for the α/ß-subunits of the GlcNAc-1-phosphotransferase. We used both cDNA and gDNA analyses to characterize a mucolipidosis type III alpha/beta patient whose clinical diagnosis was already confirmed biochemically. In a first stage only one causal mutation was identified in heterozygosity, the already described missense mutation c.1196C>T(p.S399F), both at cDNA and gDNA levels. Only after conducting inhibition of nonsense-mediated mRNA decay (NMD) assays and after the utilization of another pair of primers the second mutation, the c.3503_3504delTC deletion, was identified. Our findings illustrate that allelic dropout due to the presence of polymorphisms and/or of mutations that trigger the NMD pathway can cause difficulties in current molecular diagnosis tests.

Infantile Refsum Disease: Influence of Dietary Treatment on Plasma Phytanic Acid Levels.

Infantile Refsum disease (IRD) is one of the less severe of Zellweger spectrum disorders (ZSDs), a group of peroxisomal biogenesis disorders resulting from a generalized peroxisomal function impairment. Increased plasma levels of very long chain fatty acids (VLCFA) and phytanic acid are biomarkers used in IRD diagnosis. Furthermore, an increased plasma level of phytanic acid is known to be associated with neurologic damage. Treatment of IRD is symptomatic and multidisciplinary.The authors report a 3-year-old child, born from consanguineous parents, who presented with developmental delay, retinitis pigmentosa, sensorineural deafness and craniofacial dysmorphisms. While the relative level of plasma C26:0 was slightly increased, other VLCFA were normal. Thus, a detailed characterization of the phenotype was essential to point to a ZSD. Repeatedly increased levels of plasma VLCFA, along with phytanic acid and pristanic acid, deficient dihydroxyacetone phosphate acyltransferase activity in fibroblasts and identification of the homozygous pathogenic mutation c.2528G>A (p.Gly843Asp) in the PEX1 gene, confirmed this diagnosis. Nutritional advice and follow-up was proposed aiming phytanic acid dietary intake reduction. During dietary treatment, plasma levels of phytanic acid decreased to normal, and the patient's development evaluation showed slow progressive acquisition of new competences.This case report highlights the relevance of considering a ZSD in any child with developmental delay who manifests hearing and visual impairment and of performing a systematic biochemical investigation, when plasma VLCFA are mildly increased. During dietary intervention, a biochemical improvement was observed, and the long-term clinical effect of this approach needs to be evaluated.

Adolescent-onset Krabbe disease with an initial diagnosis of multiple sclerosis and a novel mutation.

Krabbe disease is a rare autosomal recessive leucodystrophy, with <5% of the cases having an adolescent-onset form. A 30-year-old woman with a history of a subacute episode of gait impairment at 14 years of age, and mild spastic paraparesis since then, was followed with an initial diagnosis of multiple sclerosis. After 10 years of slow disease progression without response to treatment, the initial diagnosis was reviewed, and an extensive metabolic work up revealed decreased activity of galactocerebrosidase. Genetic testing of the GALC gene proved the diagnosis of Krabbe disease and found a novel mutation. This case highlights the value of a critical eye in the initial differential diagnosis, mainly in the presence of atypical findings.

D-bifunctional protein deficiency: a cause of neonatal onset seizures and hypotonia.

BACKGROUND: Peroxisomal disorders are classified in two major groups: (1) peroxisome biogenesis disorders and (2) single peroxisomal enzyme/transporter deficiencies. D-bifunctional protein deficiency (OMIM #261515) is included in this last group of rare diseases and leads to an impaired peroxisomal beta-oxidation. D-bifunctional protein deficiencies are divided into four types based on the degree of activity of the 2-enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase protein units. PATIENT DESCRIPTION: We present the first Portuguese reported type II D-bifunctional protein deficiency patient, whose neonatal clinical picture is indistinguishable from a Zellweger spectrum disease. The clinical features and the neuroimaging findings of polymicrogyria raised suspicion of the diagnosis. After biochemical analysis, D-bifunctional protein deficiency was confirmed with the identification of a homozygous p.Asn457Tyr (N457Y) mutation of the HSD17B4 gene. The patient's parents were carriers of the mutated allele, confirming the patient homozygosity status and allowing prenatal diagnosis in future pregnancies. CONCLUSIONS: D-bifunctional protein deficiency is a rare, severe disease and the final diagnosis can only be accomplished after HSD17B4 gene sequencing. Treatment is supportive, aimed at improving nutrition and growth, controlling the central nervous system symptoms, and limiting the eventual progression of liver disease.

Assessment of a targeted resequencing assay as a support tool in the diagnosis of lysosomal storage disorders.

BACKGROUND: With over 50 different disorders and a combined incidence of up to 1/3000 births, lysosomal storage diseases (LSDs) constitute a major public health problem and place an enormous burden on affected individuals and their families. Many factors make LSD diagnosis difficult, including phenotype and penetrance variability, shared signs and symptoms, and problems inherent to biochemical diagnosis. Developing a powerful diagnostic tool could mitigate the protracted diagnostic process for these families, lead to better outcomes for current and proposed therapies, and provide the basis for more appropriate genetic counseling. METHODS: We have designed a targeted resequencing assay for the simultaneous testing of 57 lysosomal genes, using in-solution capture as the enrichment method and two different sequencing platforms. A total of 84 patients with high to moderate-or low suspicion index for LSD were enrolled in different centers in Spain and Portugal, including 18 positive controls. RESULTS: We correctly diagnosed 18 positive blinded controls, provided genetic diagnosis to 25 potential LSD patients, and ended with 18 diagnostic odysseys. CONCLUSION: We report the assessment of a next-generation-sequencing-based approach as an accessory tool in the diagnosis of LSDs, a group of disorders which have overlapping clinical profiles and genetic heterogeneity. We have also identified and quantified the strengths and limitations of next generation sequencing (NGS) technology applied to diagnosis.

[Juvenile Pompe disease: retrospective clinical study]. / Doença de Pompe juvenil: estudo retrospetivo de casuística clínica.

INTRODUCTION: Pompe disease or glycogen storage disease type II is an autosomal recessive disorder due to acid maltase deficiency. It is a rare disease with a prevalence of 1/40.000 in the dutch and african-american populations and 1/46000 in the australian population. There are three forms of clinical presentation (infantile-onset, childhood-onset and adult-onset), although the disease presents as a continuum of clinical phenotypes. Enzyme replacement therapy is available in Portugal since 2006. MATERIALS AND METHODS: The clinical files of four patients (two sisters) were analyzed retrospectively. RESULTS: In all, disease presented in the second year of life and the time to diagnosis ranged from two to eleven years. At diagnosis, all presented myopathic features with a delay in motor skills achievement and two had myocardium hypertrophy. Clinical suspicion arose as the result of respiratory failure during infection in two patients. Plasma creatine kinase and aminotransferases levels were increased in all. All patients progressed to pulmonary restrictive syndrome with chronic respiratory failure. The diagnosis was based on reduced activity of acid maltase in fibroblasts: 0 to 1.5% of the lower normal value. Muscle biopsy, performed in three patients, showed lysosomal glycogen accumulation. A c.1064T > C mutation in exon 6 of GAA (glucosidase-alpha-acid) gene was found in all patients, in homozygosity in one. In the sisters, it was associated to c.1666A > G and c.2065G > A mutations in exons 12 and 15, respectively and in the youngest patient, to c.380G > T mutation in exon 2. All patients started enzyme replacement therapy as soon as it became available, with good tolerance. The youngest patient died. The surviving patients maintain ventilatory support measures and physiotherapy. The oldest patient is wheelchair ridden and her sister keeps independent walking. The youngest uses a walking aid. CONCLUSIONS: Our cases are clinically included in the juvenile form of Pompe Disease. Pompe disease should be suspected in progressive myopathies at any age, especially those involving limb-girdle and respiratory muscles and in small infants with cardiomyopathy. High creatine kinase is a sensitive, although nonspecific, marker. Given the great variability of the genetic findings, demonstration of reduced activity of acid maltase (in leukocytes or other tissues) remains the diagnosis cornerstone of this rare disorder.

Introdução: A doença de Pompe ou glicogenose tipo II é uma doença autossómica recessiva por deficiência de maltase ácida. É uma entidade rara, com prevalência de 1/40.000 nas populações holandesa e afro-americana e 1/46000 na população australiana. Embora se distingam três formas de apresentação (infantil, juvenil e do adulto), observa-se um amplo espectro clínico. Em Portugal está disponível terapêutica enzimática de substituição desde 2006.Material e Métodos: Fez-se o estudo retrospetivo de quatro doentes (duas das quais irmãs), baseado na revisão dos processos clínicos.Resultados: Em todas, a doença manifestou-se no segundo ano de vida. O tempo até ao diagnóstico variou entre dois e onze anos. Aquando do diagnóstico, todas apresentavam miopatia com atraso de aquisições motoras e em duas havia hipertrofia miocárdica. A suspeita clínica surgiu por insuficiência respiratória em contexto infeccioso em duas doentes. Em todas havia elevação da creatina quinase e das aminotransferases. Todas evoluíram com insuficiência respiratória crónica por síndrome restritiva. O diagnóstico foi baseado na diminuição da atividade da maltase ácida em fibroblastos (0 a 1,5% do limite inferior do normal). Na biópsia muscular, realizada em três doentes, demonstrou-se acumulação lisossómica de glicogénio. Todas apresentavam a mutação c.1064T > C no exão 6 do gene GAA (glucosidase-alpha-acid), em homozigotia numa delas, associada às mutações c.1666A > G no exão 12 e c.2065G > A no exão 15 nas duas irmãs e à mutação c.380G > T no exão 2 na doente mais nova. Todas iniciaram terapia enzimática de substituiçãologo que disponível, com boa tolerância. A doente mais jovem faleceu pouco depois. As outras mantêm medidas de suporteventilatório e fisioterapia, deslocando-se a mais velha, em cadeira de rodas, mantendo a irmã marcha independente e necessitando a mais nova de andarilho.Conclusão: Os nossos casos incluem-se clinicamente na forma juvenil da doença de Pompe. A hipótese de doença de Pompe deve ser considerada em lactentes com miocardiopatia e nas miopatias progressivas, especialmente as das cinturas e dos músculos respiratórios em qualquer idade. A elevação da creatina quinase é um dado sensível, embora inespecífico. Dada a grande variabilidade dos achados genéticos, a demonstração da redução da atividade da maltase ácida continua a ser o pilar do diagnóstico.

Glycosaminoglycan storage disorders: a review.

Impaired degradation of glycosaminoglycans (GAGs) with consequent intralysosomal accumulation of undegraded products causes a group of lysosomal storage disorders known as mucopolysaccharidoses (MPSs). Characteristically, MPSs are recognized by increased excretion in urine of partially degraded GAGs which ultimately result in progressive cell, tissue, and organ dysfunction. There are eleven different enzymes involved in the stepwise degradation of GAGs. Deficiencies in each of those enzymes result in seven different MPSs, all sharing a series of clinical features, though in variable degrees. Usually MPS are characterized by a chronic and progressive course, with different degrees of severity. Typical symptoms include organomegaly, dysostosis multiplex, and coarse facies. Central nervous system, hearing, vision, and cardiovascular function may also be affected. Here, we provide an overview of the molecular basis, enzymatic defects, clinical manifestations, and diagnosis of each MPS, focusing also on the available animal models and describing potential perspectives of therapy for each one.

Alu-Alu Recombination Underlying the First Large Genomic Deletion in GlcNAc-Phosphotransferase Alpha/Beta (GNPTAB) Gene in a MLII Alpha/Beta Patient.

Mucolipidosis type II α/ß is a severe, autosomal recessive lysosomal storage disorder, caused by a defect in the GNPTAB gene that codes for the α/ß subunits of the GlcNAc-phosphotransferase. To date, over 100 different mutations have been identified in MLII α/ß patients, but no large deletions have been reported. Here we present the first case of a large homozygous intragenic GNPTAB gene deletion (c.3435-386_3602 + 343del897) encompassing exon 19, identified in a ML II α/ß patient. Long-range PCR and sequencing methodologies were used to refine the characterization of this rearrangement, leading to the identification of a 21 bp repetitive motif in introns 18 and 19. Further analysis revealed that both the 5' and 3' breakpoints were located within highly homologous Alu elements (Alu-Sz in intron 18 and Alu-Sq2, in intron 19), suggesting that this deletion has probably resulted from Alu-Alu unequal homologous recombination. RT-PCR methods were used to further evaluate the consequences of the alteration for the processing of the mutant pre mRNA GNPTAB, revealing the production of three abnormal transcripts: one without exon 19 (p.Lys1146_Trp1201del); another with an additional loss of exon 20 (p.Arg1145Serfs*2), and a third in which exon 19 was substituted by a pseudoexon inclusion consisting of a 62 bp fragment from intron 18 (p.Arg1145Serfs*16). Interestingly, this 62 bp fragment corresponds to the Alu-Sz element integrated in intron 18.This represents the first description of a large deletion identified in the GNPTAB gene and contributes to enrich the knowledge on the molecular mechanisms underlying causative mutations in ML II.

Cardiac Fabry's disease: an unusual cause of left ventricular hypertrophy.

BACKGROUND: A 64-year-old male was observed as an outpatient with atypical, non-exercise-induced chest pain and palpitations. He had arterial hypertension and marked concentric left ventricular hypertrophy. After 2.5 years of antihypertensive drug therapy the patient's blood pressure had returned to normal, but his left ventricular hypertrophy was unchanged. INVESTIGATIONS: Electrocardiography, transthoracic echocardiography, myocardial perfusion scintigraphic imaging, measurement of alpha-galactosidase A activity, gene sequencing, brain MRI, carotid artery ultrasonography, biochemical renal evaluation and cardiac Doppler tissue imaging. DIAGNOSIS: Cardiac Fabry's disease. MANAGEMENT: Losartan, hydrochlorothiazide, low-dose aspirin and bisoprolol. The patient is expected to begin enzyme replacement therapy.

Evidence for a link between sphingolipid metabolism and expression of CD1d and MHC-class II: monocytes from Gaucher disease patients as a model.

Gaucher disease (GD) is an autosomal recessive inherited defect of the lysosomal enzyme glucocerebrosidase (GluCerase) that leads to glucosylceramide (GluCer) accumulation. We previously demonstrated the existence of imbalances in certain lymphocyte populations in GD patients. We now show that GluCerase-deficient monocytes from GD patients or monocytes from healthy subjects treated with conduritol-B-epoxide (CBE), an irreversible inhibitor of GluCerase activity, display high levels of surface expression of the lipid-binding molecule CD1d. GluCerase-deficient monocytes from GD patients also showed increased surface expression of major histocompatibility complex (MHC)-class II, but not of other lysosomal trafficking molecules, such as CD63 and MHC-class I. However, CD1d and MHC-class II mRNA levels were not increased. GluCerase-deficient monocytes from GD patients undergoing enzyme replacement therapy also exhibited increased levels of CD1d and MHC-class II and imbalances in the percentage of CD4+, CD8+, and Valpha24+ T cells. Interestingly, follow-up studies revealed that enzyme replacement therapy induced a decrease in MHC-class II expression and partial correction of the CD4+ T cell imbalances. These results reveal a new link between sphingolipid accumulation in monocytes and the expression of certain MHC molecules that may result in imbalances of regulatory T cell subsets. These immunological anomalies may contribute to the clinical heterogeneity in GD patients.

Prevalence of lysosomal storage diseases in Portugal.

Lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders individually considered as rare, and few data on its prevalence has been reported in the literature. The overall birth prevalence of the 29 different LSDs studied in the Portuguese population was calculated to be 25/100000 live births, twice the prevalence previously described in Australia and in The Netherlands. The comparison of the prevalence profile of the LSDs presenting a prevalence higher than 0.5/100000 in the Portuguese, Dutch and Australian populations showed, in the Portuguese, the existence of a higher prevalence of GM2 gangliosidoses (B variant), mucolipidoses (II and III), Niemman-Pick type C and metachromatic leukodystrophy (MLD), and a lower prevalence of Pompe and Fabry. The highest prevalence value for a single LSD is the one of GM2 gangliosidoses (B variant), corresponding to 3/100000, a value which is significantly higher than the prevalence of the most frequent LSD in Dutch, Pompe disease (2/100000) and Australians, Gaucher's disease (GD) (1.8/100000). It is worth noting that the highest prevalence of GM2 gangliosidoses found in the Portuguese is mainly due to the existence of a unique subtype, the rare juvenile B1 variant.