Investigação abrangente sobre as razões da alta frequência relativa da Mucopolissacaridose tipo II no Brasil

Introdução: As mucopolissacaridoses são um grupo de 11 doenças lisossômicas causadas por defeitos enzimáticos específicos relacionados com o catabolismo dos glicosaminoglicanos, que se acumulam e podem ser identificados como biomarcadores dessas doenças. Apresentam quadro multissistêmico e progressivo, podendo haver envolvimento cognitivo. Todas elas têm padrão de herança autossômico recessivo, exceto a MPS tipo II, que é ligada ao X recessiva. O tratamento das MPS inclui medidas de suporte e reabilitação, além de tratamentos específicos disponíveis para alguns dos tipos, como o transplante de células tronco hematopoiéticas e a terapia de reposição enzimática intravenosa. A prevalência para cada uma delas varia conforme o país estudado, sendo que a MPS II, ao contrário do que acontece na maioria dos países da América do Norte e da Europa, é o tipo mais comum no Brasil. Objetivos: Investigarfatores que possam explicar a maior frequência relativa de MPS II no Brasil; verificar se a alta frequência relativa de MPS II tem maior predominância em alguma região brasileira; avaliar a variabilidade fenotípica intra-familiar em pacientes com MPS II; avaliar o tempo de atraso no diagnóstico dessa patologia no Brasil. Métodos: O estudo foi realizado com dados de pacientes diagnosticados com MPS pelo Serviço de Genética Médica do HCPA e pela Rede MPS Brasil entre 1982 e 2020. Nós calculamos a incidência das MPS no Brasil, por região e estados da federação a partir dos dados da nossa amostra e de informações do Sistema de Informações sobre Nascidos Vivos do sistema de saúde brasileiro. Para a MPS II, estudamos o perfil molecular dos pacientes e de suas mães. Também revisamos dados clínicos registrados em prontuários e relacionamos o fenótipo neuronopático e não-neuronopático da MPS II com as variantes encontradas nesses pacientes. Resultados: No Brasil, a prevalência da MPS ao nascimento (para cada 100.000 nascidos vivos) entre 1994 e 2018 foi de 1,57 e foi maior para a MPS II nas regiões centro-oeste, norte, sudeste e sul. Na região nordeste, a MPS VI foi o tipo mais comum. Estudando o perfil molecular de 280 pacientes de 206 famílias com MPS II, observamos que mutações de ponto foram encontradas em 70% dos casos, sendo as variantes patogênicas do tipo missense as mais comumente detectadas no gene IDS. Considerando as formas neuronopática e não-neuronopática da MPS II, houve concordância do fenótipo entre os familiares afetados, exceto entre dois meio-irmãos. As mães dos pacientes com MPS II foram portadoras da variante considerada patogênica no gene IDS em 82% dos casos. Considerando os dados clínicos, a mediana do atraso ao diagnóstico para as MPS em geral foi de 40 (15,25 – 84) meses e não houve diferença na idade ao diagnóstico entre o primeiro caso e os demais casos de MPS diagnosticados em uma mesma família. Para pacientes com MPS II, a forma neuronopática foi diagnosticada mais cedo do que a forma não-neuronopática. Consanguinidade parental foi detectada em 4,1% dos casos de MPS II e em 35,1% dos casos com as formas autossômicas recessivas, sendo mais encontrada no Ceará, Distrito Federal e Paraíba e com a região nordeste mostrando uma tendência à maior consanguinidade. Conclusão: Na ausência de uma variante patogênica que contribua particularmente para a sua alta frequência, o maior número de afetados nas famílias com MPS II, associada à baixa taxa de consanguinidade na população em geral, podem ser fatores responsáveis pela maior proporção relativa de MPS II no Brasil, para a qual parece contribuir a falta de um aconselhamento genético eficiente.Introduction: Mucopolysaccharidoses are a group of 11 lysosomal diseases caused by specif enzymatic defects related to the catabolism of glycosaminoglycans, which accumulate and can be indentified as biomarkers. They present as multisystemic and progressive diseases, and there may be cognitive involvement. All of them are inherited as an autosomal recessive trait, except for MPS type II, which is X-linked recessive. Treatment for MPS includes supportive and rehabilitative measures, as well as specific treatments availaible for some types, such as hematopoietic stem cell transplantation and intravenous enzyme replacement therapy. Their prevalence varies according to the country studied and, unlike what happens in most American and European countries, MPS II is the most common in Brazil. Objectives: To investigate factors that may explain the higher relative frequency of MPS II in Brazil; verify whether the high relative frequency of MPS II is related to any Brazilian region; to assess intra-familial phenotypic variability in patients with MPS II; to assess the delay in diagnosis for MPS in Brazil. Methods: The study was carried out with data from patients diagnosed with MPS from the Medical Genetics Service of Hospital de Clínicas de Porto Alegre and the MPS Brazil Network between 1982 and 2020. We calculated the incidence of MPS in Brazil, per region and federation states using data from our sample and from the Information System on Live Births of the Brazilian Health System. For MPS II, we studied the molecular profile of patients and their mothers. We also reviewed clinical data from medical records and related the neuronopathic and the nonneuronopathic MPS II phenotype with the variants found in the patients. Results: In Brazil, the birth prevalence of MPS (per 100,000 live births) between 1994 and 2018 was 1.57 and it was higher for MPS II on the Midle-West, North, Southeast, and South regions. In the Northeast region, the MPS VI was the most common type. Molecular profile of 280 patients from 206 families with MPS II showed that point mutations were found in 70% of the cases, with pathogenic missense variants being the most commonly detected in the IDS gene. Considering the neuronopathic and non-neuronopathic forms of MPS II, affected family members had concordant phenotype, except between two half-siblings. The mothers of patients with MPS II were carriers of the variant considered pathogenic in the IDS gene in 82% of the cases. Considering the clinical data, the median delay in diagnosis for MPS in general was 40 (15.25 – 84) months and there was no difference in the age at diagnosis between the first case and further MPS cases diagnosed in the same family. For patients with MPS II, the neuronopathic form was diagnosed earlier than the non-neuronopathic form. Parental consanguinity was detected in 4.1% in MPS II cases and in 35.1% of the autossomal recessive ones, being more frequent in Ceará, Distrito Federal and Paraíba, and also the Northeast region showed a trend towards consanguinity. Conclusion: In the absence of a particular pathogenic variant that explains its high relative frequency, the higher number of affected members from MPS II families, associated with the low consanguinity of the general population may be factors responsible for the higher incidence of this MPS type in Brazil, for which the lack of adequate genetic counseling seems to contribute

Detection of mosaic variants in mothers of MPS II patients by next generation sequencing

Mucopolysaccharidosis type II is an X-linked lysosomal storage disorder caused by mutations in the IDS gene that encodes the iduronate-2-sulfatase enzyme. The IDS gene is located on the long arm of the X-chromosome, comprising 9 exons, spanning approximately 24 kb. The analysis of carriers, in addition to detecting mutations in patients, is essential for genetic counseling, since the risk of recurrence for male children is 50%. Mosaicism is a well-known phenomenon described in many genetic disorders caused by a variety of mechanisms that occur when a mutation arises in the early development of an embryo. Sanger sequencing is limited in detecting somatic mosaicism and sequence change levels of less than 20% may be missed. The Next Generation Sequencing (NGS) has been increasingly used in diagnosis. It is a sensitive and fast method for the detection of somatic mosaicism. Compared to Sanger sequencing, which represents a cumulative signal, NGS technology analyzes the sequence of each DNA read in a sample. NGS might therefore facilitate the detection of mosaicism in mothers of MPS II patients. The aim of this study was to reanalyze, by NGS, all MPS II mothers that showed to be non-carriers by Sanger analysis. Twelve non-carriers were selected for the reanalysis on the Ion PGM and Ion Torrent S5 platform, using a custom panel that includes the IDS gene. Results were visualized in the Integrative Genomics Viewer (IGV). We were able to detected the presence of the variant previously found in the index case in three of the mothers, with frequencies ranging between 13 and 49% of the reads. These results suggest the possibility of mosaicism in the mothers. The use of a more sensitive technology for detecting low-level mosaic mutations is essential for accurate recurrence-risk estimates. In our study, the NGS analysis showed to be an effective methodology to detect the mosaic event

Updated birth prevalence and relative frequency of mucopolysaccharidoses across Brazilian regions

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by 11 enzyme deficiencies, classified into seven types. Data on the birth prevalence of each MPS type are available for only a few countries, and the totality of cases may be underestimated. To determine the epidemiological profile of MPS in each Brazilian region, we analyzed data collected between 1982 and 2019 by a national reference laboratory and identified 1,652 patients. Using data between 1994 and 2018, the birth prevalence (by 100,000 live births) for MPS was 1.57. MPS II was the most common type of MPS in Brazil, and its birth prevalence was 0.48 (0.94 considering only male births). Regarding the number of cases per region, MPS II was the most frequent in the North and Center-West (followed by MPS VI), and also in the Southeast (followed by MPS I); MPS I and MPS II were the most common types in the South; and MPS VI was the most common in the Northeast (followed by MPS II). The differences observed in the relative frequencies of MPS types across Brazilian regions are likely linked to founder effect, endogamy, and consanguinity, but other factors may be present and need further investigation

Influence of STAT1 expression in response to chemotherapy in highgrade serous ovarian cancer

O câncer de ovário é uma importante causa de mortalidade. O subtipo seroso de alto grau é o mais frequente e caracteriza-se por comportamento agressivo, com crescimento rápido e metástase precoce. A falta de ferramentas para diagnóstico em estádios iniciais e a insuficiência de resposta à quimioterapia convencional são dois principais obstáculos para o manejo do câncer seroso de ovário. A detecção precoce neste tumor é complicada por sintomas inespecíficos e ausência de biomarcadores confiáveis. Além disso, o desenvolvimento de resistência à quimioterapia é um desafio para o tratamento, que é geralmente baseado na combinação de platina e paclitaxel. A influência do microambiente tumoral na resposta terapêutica ainda é pouco conhecida. No entanto, há evidências crescentes de que a resposta imunológica pré-existente pode estar relacionada com a variação da sensibilidade à quimioterapia. O microambiente imunorreativo foi associado à melhor prognóstico no câncer do ovário seroso de alto grau em recente estudo canadense. Proteínas da família de Transdutores de Sinal e Ativadores da Transcrição (STATs) participam da regulação de citocinas e são determinantes nas respostas imunes no microambiente tumoral, podendo promover ou inibir o crescimento tumoral. Dados recentes mostram que a expressão elevada de um dos reguladores de STAT, STAT1 atua na tumorigênese do câncer de ovário, facilitando a resposta imune e, potencialmente, alterando a resposta à quimioterapia. Para avaliar o papel da expressão de STAT1 como biomarcador preditivo em 65 pacientes brasileiras com câncer seroso de ovário, examinamos os níveis de STAT1 por imunoistoquímica, e analisamos se houve correlação entre expressão dessa proteína e resposta clínica. Alta expressão de STAT1 foi significativamente associada maior intervalo livre de doença (P=0,0256) e maior sobrevida global (P=0,0193). Estes achados da coorte brasileira, com tempo de seguimento maior que cinco anos, confirmam a associação entre alta expressão de STAT1 e melhor resposta à quimioterapia, e fornecem validação adicional desta proteína como um biomarcador preditivo. Além disso, estes resultados chamam atenção para a possibilidade de utilizar a via de STAT1 para o desenvolvimento de novos medicamentos imunomoduladores, que poderiam melhorar a resposta ao tratamentoOvarian cancer is a major cause of mortality worldwide. The most frequent subtype is high grade serous, which is characterized by aggressive behavior with rapid growth and early metastasis. Lack of early diagnostic tools and failure of response to conventional chemotherapies are two major impediments to serous ovarian cancer management. Early detection in initial stages is complicated by non-specific symptoms and lack of reliable biomarkers. In addition, development of chemotherapy resistance is a challenge for treatment, which is generally based on combination of platinum and paclitaxel. The influence of the microenvironment of the tumor on therapeutic response is still unknown. However, there is increasing evidence that a pre-existing immunological response may be related to variation in chemotherapy sensitivity. The immunoreactive microenvironment has been shown to be associated with better prognosis in high grade serous ovarian cancer in a recent Canadian study. The Signal Transducer and Activator of Transcription (STAT) proteins regulate cytokines and are central in determining whether immune responses in the tumor microenvironment promote or inhibit cancer. Recent data show that high expression of one of the STAT regulators, STAT1, operates in ovarian cancer tumorigenesis, facilitating immune response and potentially altering response to chemotherapy. To evaluate the role of STAT1 expression as a predictive biomarker in 65 Brazilian serous ovarian cancer patients, we examined STAT1 levels by immunohistochemistry to determine if there was correlation between expression of this protein and clinical response. High expression of STAT1 was significantly associated with both improved disease-free survival (P=0,0256) and overall survival (P=0,0193). These findings from a Brazilian cohort after more than five years of follow up confirm the association of high STAT1 expression with better response to chemotherapy, and provide additional validation of this protein as a predictive biomarker. Moreover these results draw attention to the possibility of utilizing the STAT1 pathway for the development new immunomodulator drugs, that could enhance response to treatmen