Caracterização clínica e bioquímica de pacientes com galactosemia clássica

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Long-term restoration of alpha-L-iduronidase activity in fibroblasts from patients with mucopolysaccharidosis type I after non-viral gene transfer

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder due to deficiency of alpha-L-iduronidase (IDUA). Limitations such as need of weekly injection, high morbidity and mortality  and high cost of the current treatments show the need for new approaches to treat this disease. In this work we aimed to correct fibroblasts from a MPS I patient using non-viral gene therapy. Using a plasmid encoding the human IDUA cDNA, we achieved stable high IDUA levels in transfected fibroblasts up to 6 months of treatment. These results serve as proof-of concept that a non-viral approach can correct the enzyme deficiency in cells from lysosomal storage disorders patients, which can be used as a tool for research a series of disease aspects. Future studies will focus on verify if this approach can be useful in small animals and clinical trials

Identificação de mutações no gene da arilsulfatase A através de PCR em tempo real

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Fast and robust protocol for prenatal diagnosis of mucopolysaccharidosis Type II

Introduction: Mucopolysaccharidosis type II (MPSII) is an X-linked lysosomal disorder caused by deficiency of iduronate-2-sulfatase (IDS). In this study, we proposed a new protocol for prenatal diagnosis, using DNA obtained from amniotic fluid cells that did not attach to the bottom of the culture flask after the first medium change. Methods: Four pregnant MPS II carriers were referred to the Medical Genetics Service of Hospital de Clinicas de Porto Alegre for a prenatal diagnosis and identification of the disease, which were performed by polymerase chain reaction (PCR) amplification, restriction fragment length polymorphism, and sequencing according to the mutation previously found in the family. Results: The analysis indicated the absence of mutation in three fetal materials and the presence of mutation in one case. Concomitantly, cytogenetic and biochemical analyses were performed after 12 days of cell culture, and only one case showed absence of enzyme activity, confirming the molecular analysis. Conclusions: This diagnostic protocol designed to provide more robust results and safer genetic counseling suggests that DNA obtained from floating amniotic fluid cells can be used as a source of fetal material to allow a faster alternative for prenatal care through molecular analysis. Determination of IDS gene mutation in fetal amniotic fluid cells together with IDS enzyme activity testing is a rapid, sensitive and accurate method for prenatal diagnosis of MPS II for high-risk pregnant women

Mucopolysaccharidosis Type I in a Dog

Background: Mucopolysaccharidoses (MPS) are a group of rare illnesses caused by deficient activity of enzymes required for degradation of glycosaminoglycans (GAGs). Each type of MPS is caused by mutations in one of the genes that encode the 11 acid hydrolases involved in this degradation process, which are present in the lysosomes. Progressive accumulation of GAGs in the lysosomes result in cellular dysfunction and multisystemic clinical signs, with consequent decrease in quality of life and lifespan of the affected patients. The objective of the present work is to report a case of MPS type I in a dog.Case: A mixed-breed male dog of approximately 2-month-old weighing 2.5 kg was referred to Hospital Veterinário de Uberaba with a distended abdomen. At the clinical examination, the patient exhibited a regular nutritional status, pale mucous membranes, 7% dehydration, an arterial pulse rate of 120 beats per minute, a respiratory rate of 40 breaths per minute, and a heart rate of 120 beats per minute. There were increased abdominal volume and tension, and hepatosplenomegaly. The abdominal percussion exam produced a dull tone. Additional findings included muscular atrophy, increased volume in the metaphyseal areas of the thoracic and pelvic limbs, valgus limb deformity in the thoracic limbs, and instability of the hip joint. Radiographic examination revealed a series of bone alterations such as reduced vertebral bodies, a generalized decrease in radiopacity, thin cortical areas in long bones, narrowing of the pelvic canal, and marked deformation and irregularities in acetabular and epiphyseal (both proximal and distal) areas of the femurs and tibias. Ankylosis of the tibiotarsal and tarsometatarsal joints was also observed. There was also loss of trabecular structure and irregularities on the surfaces of all epiphyses of the bones, epiphyseal lines markedly open, and bones that were shorter and thicker than normal. The suspected diagnoses were pseudoachondroplasia and mucopolysaccharidosis. In view of the clinical and radiographic findings, tests were performed to investigate the clinical suspicion of MPS. Consequently, qualitative and quantitative tests of GAGs in the urine, as well as a blood enzymatic essay, were requested; results confirmed the diagnosis of MPS type I. Intensive treatment allowed the patient to reach adulthood. Whenever new clinical signs emerged, they were treated palliatively. As the disease became more severe, the patient died at the age of 3 years.Discussion: Mucopolysaccharidosis type I is a rare disease that exhibits variable clinical signs and for which there is no specific treatment in dogs; these characteristics hinder diagnosis and treatment of patients as the one described in this report. The major clinical signs observed in this case are in agreement with those reported in the literature, according to which the disease can cause severe alterations such as bone defects, increased volume and deformities in the joints of the limbs, corneal opacity, and enlargement of abdominal organs such as the liver and spleen. In considering diagnostic methods for MPS, the main screening test is quantification of GAGs in the urine. The confirmatory test for MPS consists of analysis of the activity of specific lysosomal enzymes in a blood sample; this test allowed the establishment of a diagnosis in this case. Enzyme replacement therapy, in which a recombinant enzyme is used, have yielded good results in humans and dogs. However, this treatment does not cure the disease – it only attenuates the clinical signs and enables the patient to reach adulthood. Access to enzyme replacement therapy was not possible in the present case. As a conclusion, MPS should be included in the differential diagnosis of developmental diseases in puppies. This highlights the importance of further studies and reports on this disease

Newborn screening for lysosomal disorders in Brazil : a pilot study using customized fluorimetric assays

Lysosomal storage disorders (LSDs) are a group of genetic disorders characterized by deficiency of specific lysosomal enzymes. In general, patients are clinically normal at birth, and progressively develop severe signs and symptoms. Diagnosis is usually made several years after onset of manifestations, preventing patients to have the benefits of the early treatment. Newborn screening programs are being considered for LSDs to allow early diagnosis and treatment. The present study evaluated the feasibility of a customized screening approach based on modified fluorometric assays with reduced amounts of reagents, substrates and samples for: mucopolysaccharidosis (MPS) type I (MPS I), MPS VI, Fabry, Gaucher, and Pompe diseases. We also evaluated the advantages of including blood chitotriosidase and urinary glycosaminoglycans in the protocol. By the measurement of the specific diseaseassociated enzymes (plus blood chitotriosidase and urinary glycosaminoglycans) we analyzed 834 de-identified DBS of unselected newborns. No positive case was detected, and the false-positive rates were low. Taking into consideration the limitations of this methodology, we believe that, after defining proper cutoffs, it could be a viable alternative to provide NBS for LSDs by laboratories that may not be able to afford the commercial methods available

Lysosomal diseases : overview on current diagnosis and treatment

Lysosomal diseases (LDs), also known as lysosomal storage diseases (LSDs), are a heterogeneous group of conditions caused by defects in lysosomal function. LDs may result from deficiency of lysosomal hydrolases, membrane-associated transporters or other non-enzymatic proteins. Interest in the LD field is growing each year, as more conditions are, or will soon be treatable. In this article, we review the diagnosis of LDs, from clinical suspicion and screening tests to the identification of enzyme or protein deficiencies and molecular genetic diagnosis. We also cover the treatment approaches that are currently available or in development, including hematopoietic stem cell transplantation, enzyme replacement therapy, small molecules, and gene therapy

Monitoring of phenylalanine levels in patients with phenylketonuria using dried blood spots : a comparison of two methods

Phenylketonuria (PKU) is caused by deficient activity of phenylalanine hydroxylase (PAH), responsible for the conversion of phenylalanine (Phe) to tyrosine (Tyr). Monitoring of patients with PKU requires the measurement of Phe in plasma using highperformance liquid chromatography (HPLC) or in dried blood spots (DBS) using different techniques to adjust treatment strategy. The objective of this study was to evaluate Phe levels in DBS measured by two different methods and compare them with Phe levels measured in plasma by HPLC. We analyzed 89 blood samples from 47 PKU patients by two different methods: fluorometric method developed in-house (method A) and the commercially available PerkinElmer® Neonatal Phenylalanine Kit (method B) and in plasma by HPLC. The mean Phe levels by method A, method B, and HPLC were 430.4±39.9μmol/L, 439.3±35.4μmol/L, and 442.2±41.6μmol/L, respectively. The correlation values between HPLC and methods A and B were 0.990 and 0.974, respectively (p<0.001 for both). Our data suggest that methods A and B are useful alternatives for monitoring Phe levels in patients with PKU, with method A being in closer agreement with the reference standard (HPLC)