Resumo em Inglês:

Abstract Brazil is a country of continental dimensions and most genetic services are concentrated in the Southeast and South, including the Medical Genetics Service of the Hospital de Clínicas de Porto Alegre (MGS/HCPA). As many areas on the country do not have adequate medical genetics support, networks were designed to extend the service of the MGS/HCPA reference center. This paper presents the information and diagnosis networks that have their headquarters at MGS/HCPA: SIAT (National Information System on Teratogenic Agents), SIEM (Information Service on Inborn Errors of Metabolism), Alô Genética (Hello Genetics - Medical Genetics Information Service for Primary Health Care Professionals); Rede MPS Brasil (MPS-Mucopolysaccharidosis Brazil Network); Rede EIM Brasil (IEM-Inborn Errors of Metabolism Brazil Network), Rede NPC Brasil (Niemann-Pick C - NPC Brazil Network), Rede DLD Brasil (LSD-Lysosomal Storage Disorders Brazil Network), Rede DXB (MSUD-Maple Syrup Urine Disease Network), RedeBRIM (Brazilian Network of Reference and Information in Microdeletion Syndromes Project), Rede Neurogenética (Neurogenetics Network), and Rede Brasileira de Câncer Hereditário (Brazilian Hereditary Cancer Network). These tools are very useful to provide access to a qualified information and/or diagnostic service for specialized and non-specialized health services, bypassing difficulties that preclude patients to access reference centers.

Resumo em Inglês:

Abstract 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.

Resumo em Inglês:

Abstract Organic acidurias and aminoacidopathies are groups of frequent inborn errors of metabolism (IEMs), which are caused by mutations in specific genes that lead to loss of protein/enzyme or transport function with important deleterious effects to cell metabolism. Since a considerable number of such disorders are potentially treatable when diagnosed at an early stage of life, diagnosis is crucial for the patients. In the present report, we describe symptomatic individuals referred to our service that were diagnosed with these disorders from 2006 to 2016. We used blood and urine samples from 21,800 patients suspected of aminoacidopathies or organic acidemias that were processed by the analytical techniques reverse phase high-performance liquid chromatography for amino acid quantification and gas chromatography coupled to mass spectrometry for organic acid detection. Analysis of dried blood spots by liquid chromatography-tandem mass spectrometry was used in some cases. We detected 258 cases of organic acidurias, and 117 patients with aminoacidopathies were diagnosed. Once diagnosis was performed, patients were promptly submitted to the available treatments with clear reduction of mortality and morbidity. The obtained data may help pediatricians and metabolic geneticists to become aware of these diseases and possibly expand newborn screening programs in the future.

Resumo em Inglês:

Abstract Cri-du-chat syndrome (CdCs) is one of the most common contiguous gene syndromes, with an incidence of 1:15,000 to 1:50,000 live births. To better understand the etiology of CdCs at the molecular level, we investigated theprotein–protein interaction (PPI) network within the critical chromosomal region 5p15.3–p15.2 associated with CdCs using systemsbiology. Data were extracted from cytogenomic findings from patients with CdCs. Based on clinical findings, molecular characterization of chromosomal rearrangements, and systems biology data, we explored possible genotype–phenotype correlations involving biological processes connected with CdCs candidate genes. We identified biological processes involving genes previously found to be associated with CdCs, such as TERT, SLC6A3, and CTDNND2, as well as novel candidate proteins with potential contributions to CdCs phenotypes, including CCT5, TPPP, MED10, ADCY2, MTRR, CEP72, NDUFS6, and MRPL36. Although further functional analyses of these proteins are required, we identified candidate proteins for the development of new multi-target genetic editing tools to study CdCs. Further research may confirm those that are directly involved in the development of CdCs phenotypes and improve our understanding of CdCs-associated molecular mechanisms.

Resumo em Inglês:

Abstract Lysosomal storage disorders (LSDs) constitute a heterogeneous group of approximately 50 genetic disorders. LSDs diagnosis is challenging due to variability in phenotype penetrance, similar clinical manifestations, and a high allelic heterogeneity. A powerful tool for the diagnosis of the disease could reduce the “diagnostic odyssey” for affected families, leading to an appropriate genetic counseling and a better outcome for current therapies, since enzyme replacement therapies have been approved in Brazil for Gaucher, Fabry, and Pompe diseases, and are under development for Niemann-Pick Type B. However, application of next-generation sequencing (NGS) technology in the clinical diagnostic setting requires a previous validation phase. Here, we assessed the application of this technology as a fast, accurate, and cost-effective method to determine genetic diagnosis in selected LSDs. We have designed two panels for testing simultaneously 11 genes known to harbor casual mutations of LSDs. A cohort of 58 patients was used to validate those two panels, and the clinical utility of these gene panels was tested in four novel cases. We report the assessment of a NGS approach as a new tool in the diagnosis of LSDs in our service.

Resumo em Inglês:

Abstract Mucopolysaccharidosis (MPS) are a group of rare genetic disorders caused by deficiency in the activity of specific lysosomal enzymes required for the degradation of glycosaminoglycans (GAGs). A defect in the activity of these enzymes will result in the abnormal accumulation of GAGs inside the lysosomes of most cells, inducing progressive cellular damage and multiple organ failure. DNA samples from 70 patients with biochemical diagnosis of different MPSs genotypes confirmed by Sanger sequencing were used to evaluate a Next Generation Sequencing (NGS) protocol. Eleven genes related to MPSs were divided into three different panels according to the clinical phenotype. This strategy led to the identification of several pathogenic mutations distributed across all exons of MPSs-related genes. We were able to identify 96% of all gene variants previously identified by Sanger sequencing, showing high sensitivity in detecting different types of mutations. Furthermore, new variants were not identified, representing 100% specificity of the NGS protocol. The use of this NGS approach for genotype identification in MPSs is an attractive option for diagnosis of patients. In addition, the MPS diagnosis workflow could be divided in a two-tier approach: NGS as a first-tier followed by biochemical confirmation as a second-tier.

Resumo em Inglês:

Abstract Germline mutations in BRCA1 and BRCA2 (BRCA) genes confer high risk of developing cancer, especially breast and ovarian tumors. Since the cloning of these tumor suppressor genes over two decades ago, a significant amount of research has been done. Most recently, monoallelic loss-of-function mutations in PALB2 have also been shown to increase the risk of breast cancer. The identification of BRCA1, BRCA2 and PALB2 as proteins involved in DNA double-strand break repair by homologous recombination and of the impact of complete loss of BRCA1 or BRCA2 within tumors have allowed the development of novel therapeutic approaches for patients with germline or somatic mutations in said genes. Despite the advances, especially in the clinical use of PARP inhibitors, key gaps remain. Now, new roles for BRCA1 and BRCA2 are emerging and old concepts, such as the classical two-hit hypothesis for tumor suppression, have been questioned, at least for some BRCA functions. Here aspects regarding cancer predisposition, cellular functions, histological and genomic findings in BRCA and PALB2-related tumors will be presented, in addition to an up-to-date review of the evolution and challenges in the development and clinical use of PARP inhibitors.

Resumo em Inglês:

Abstract Breast cancer (BC) risk assessment models base their estimations on different aspects of a woman’s personal and familial history. The Gail and Tyrer–Cuzick models are the most commonly used, and BC risks assigned by them vary considerably especially concerning familial history. In this study, our aim was to compare the Gail and Tyrer-Cuzick models after initial screening for familial history of cancer in primary care using the FHS-7 questionnaire. We compared 846 unrelated women with at least one positive answer to any of the seven FHS-7 questions (positive group) and 892 unrelated women that answered negatively (negative group). Concordance between BC risk estimates was compared by Bland-Altman graphics. Mean BC risk estimates were higher using the Tyrer-Cuzick Model in women from the positive group, while women from the negative group had higher BC risk estimates using the Gail model. With increasing estimates, discordance also increased, mainly in the FHS-7 positive group. Our results show that in women with a familial history of cancer, the Gail model underestimates risk and the Tyrer-Cuzick seems to be more appropriate. FHS-7 can be a useful tool for the identification of women with higher breast cancer risks in the primary care setting.

Resumo em Inglês:

Abstract Machado-Joseph disease (SCA3/MJD) is the most common spinocerebellar ataxia worldwide, and particularly so in Southern Brazil. Due to an expanded polyglutamine at ataxin-3, SCA3/MJD presents a relentless course with no current disease modifying treatment. Clinical scales used to measure SCA3/MJD progression present moderate effect sizes, a major drawback for their use as main outcomes in clinical trials, given the rarity and slow progression of the disease. This limitation might be overcome by finding good surrogate markers. We present here a review of studies on peripheral and neurophysiological markers in SCA3/MJD that can be candidates for state biomarkers. Data on markers already studied were summarized, giving emphasis on validation against clinical scale, and responsiveness to change. While some biological fluid compounds and neurophysiological parameters showed poor responsiveness, others seemed to be good candidates. Some potential candidates that are waiting for responsiveness studies were serum levels of neuron specific enolase, vestibulo-ocular reflex and video-oculography. Candidates evaluated by RNA and microRNA expression levels need further studies to improve their measurements. Data on peripheral levels of Beclin-1 and DNAJB1 are promising but still incipient. We conclude that several potential candidates should follow onto validating studies for surrogate state biomarkers of SCA3/MJD.

Resumo em Inglês:

Abstract Treatment of moderate and severe forms of osteogenesis imperfecta (OI) with cyclic pamidronate at the Reference Center for OI Treatment in Southern Brazil was studied. A retrospective cohort study was conducted from 2002 to 2012. Data were obtained during inpatient (drug infusion) and outpatient care. Clinical data, including the presence of blue sclerae, dentinogenesis imperfecta, history and site of the fractures, biochemical data, including calcium, phosphorus, and alkaline phosphatase levels, were systematically collected. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA). Forty-five patients (26 females) were included in the study, and the age of the patients at the time of diagnosis ranged from 1 to 144 months, with a median age (p25-p75) of 38 (5-96) months. Most cases presented OI-4 (51.1%), and the median age of the patients at the start of treatment was 3.3 years (25-75 percentiles: 0.5 - 8.7 years). Twenty-four patients (54.5%) had some adverse events or intercurrences during treatment, and the treatment compliance mean was 92.3% (± 10.7). The treatment with intravenous pamidronate has shown to be safe, well-tolerated, and effective in regard to the improvement of BMD and the reduction of the number of fractures in children and adolescents with OI.

Resumo em Inglês:

Abstract Lysosomal storage diseases (LSDs) are inherited conditions caused by impaired lysosomal function and consequent substrate storage, leading to a range of clinical manifestations, including cardiovascular disease. This may lead to significant symptoms and even cardiac failure, which is an important cause of death among patients. Currently available treatments do not completely correct cardiac involvement in the LSDs. Gene therapy has been tested as a therapeutic alternative with promising results for the heart disease. In this review, we present the results of different approaches of gene therapy for LSDs, mainly in animal models, and its effects in the heart, focusing on protocols with cardiac functional analysis.

Resumo em Inglês:

Abstract Trisomy 18 (T18) and trisomy 13 (T13) are polymalformative syndromes associated with a high rate of spontaneous abortions, intrauterine death, and short postnatal life. This study describes the overall outcome in a country where the therapeutic interruption of pregnancy is not available. The medical records of women with prenatal diagnosis of full trisomy of T13 or T18 between October 1994 and October 2017 were analyzed in order to describe their natural outcomes. Thirteen cases of T13 and 29 cases of T18 were included. The miscarriage rate was 9% for T18 and no cases for T13. Intrauterine fetal death occurred in 46% and 52% of cases for T13 and T18, respectively. The rate of live births for T13 was 54%, and the median survival was one day (95% CI -33.55 - 90.40) and 71% died in the first 24 hours of life. The rate of live births for T18 was 37% and the median survival was two days (95% CI -1.89 - 13.17); 90% of the affected babies died within first week of life. For the affected babies reaching the first year of life and for those who lived longer, multiple invasive and expensive procedures were required, without success in prolonging life beyond 180 days. This large series provides information for professionals and women regarding the natural histories of T13 and T18. Results of this study are consistent with those referenced in the literature, emphasizing the need of structured protocols and guidelines aiming early T13 and T18 diagnosis, prenatal care, gestation/parents follow-up, and counseling processes. For those couples with earlier diagnosis, a better follow-up and counseling during the prenatal care lead to the option for a support or palliative management of the newborn. Finally, when the counseling process is appropriate, it becomes easier to take decisions respecting the parent’s autonomy and to look for better outcomes for both, the mother and the fetus.

Resumo em Inglês:

Abstract In 1990, the first Teratogen Information Service in Brazil (SIAT) was implemented in the Medical Genetics Service at Hospital de Clinicas de Porto Alegre. SIAT is a free-to-use information service both to health professionals and the general population, especially to women who are pregnant or planning pregnancy. The main objective of this paper is to present the activities of SIAT in its initial years (1990-2006), compared to those in the last decade (2007-2017). In addition we review the scientific contribution of SIAT in the field of human teratogenesis. Since 1990, SIAT received 10,533 calls. Use of medications were the main reason for concern, accounting for 74% of all questions, followed by other chemical exposures (occupational, cosmetics, environmental), and maternal infectious diseases. Among its main contributions to scientific knowledge was the collaboration for the identification of two new human teratogens: misoprostol in the 1990s and Zika virus in 2015/16. In conclusion, SIAT is still evolving, as is the Medical Genetics Service that hosts it. Through its 27 years of existence more than 300 undergraduate and graduate students have rotated at SIAT. Presently, SIAT is expanding the research to experimental teratogenesis and to investigation of molecular mechanisms of teratogens.

Resumo em Inglês:

Abstract Rare diseases are defined as conditions with a prevalence of no more than 6.5 per 10,000 people. Although each rare disease individually affects a small number of people, collectively, the 6,000 to 8,000 rare conditions (80% of them with genetic cause) affect around 8% of the world’s population. Research about the natural history and underlying pathophysiological mechanisms of rare diseases, as well as clinical trials with new drugs, are important and necessary to develop new strategies for the treatment of these conditions. This report describes the experience of a clinical research group working with rare diseases in a reference center for lysosomal diseases in Brazil (Medical Genetics Service, Hospital de Clínicas de Porto Alegre). The activities of this research group enabled its participation in several international multicenter clinical research protocols related to the natural history or therapy development for rare genetic diseases. This participation has allowed the development of personal skills and institutional facilities for clinical research. The clinical research developed in our center has raised the quality of the medical assistance provided to non-clinical research patients in addition to enabling early access to new therapies to many patients with orphan conditions.

Resumo em Inglês:

Abstract Rare genetic disorders are currently in the spotlight due to the elevated number of different conditions and significant total number of affected patients. The study of these disorders is extremely helpful for the elucidation of physiological processes related with complex disorders. Isolated populations are instrumental for the study of genetic disorders, considering their homogeneity and high proportion of affected patients in a small geographic area. These favorable conditions lead to the creation of a new discipline, known as “population medical genetics”, which integrates medical genetics, population genetics, epidemiological genetics and community genetics. In order to develop practical activities in this new discipline, the National Institute of Population Medical Genetics (INaGeMP) was created in 2008 in Brazil. INaGeMP has developed several tools and funded numerous research activities. In this review, we highlight three successful projects developed in the first 10 years of INaGeMP activities (2008-2018): a newborn screening pilot study for MPS VI in Northeast Brazil, the study of Machado-Joseph disease in Brazilian families with Azorian ancestry, and the high twinning rate in a small town in southern Brazil. The results of these projects in terms of scientific output and contributions to the affected communities highlight the success and importance of INaGeMP.