Les maladies rétiniennes héréditaires représentent un groupe de pathologie hétérogène sur le plan phénotypique et génétique. Elles sont dues à une dysfonction ou une dégénérescence de la neurorétine ou de l’épithélium pigmentaire rétinien. Elles peuvent être présente de manière isolée ou être associée à des atteintes extraoculaires dans les formes syndromiques. Le travail de thèse porte sur l’identification moléculaire de gènes responsables de formes rares de pathologie rétinienne syndromique incluant les ciliopathies dont le syndrome de Bardet-Biedl, caractérisé notamment par une dégénérescence rétinienne constante, et les microcéphalies associées à une choriorétinopathie. Par une approche de séquençage exomique, nous avons pu identifier trois nouveaux gènes impliqués dans ces pathologies rétiniennes syndromiques et confirmer l’implication d’un gène dans le syndrome de Bardet-Biedl. L’analyse des phénotypes rétiniens d’une cohorte de patients présentant un syndrome de Bardet-Biedl a permis la description d’un phénotype atypique avec atteinte prédominante des cônes. / Inherited retinal diseases (IRDs) represent a clinically and genetically heterogeneous group of rare pathologies. These disorders result of a dysfunction or a degeneration of the photoreceptors or the retinal pigment epithelium. IRDs can be subdivided in isolated forms, and syndromic forms that involve non–ocular features. This work deals with the molecular identification of genes implicated in rare forms of syndromic retinal diseases, including the ciliopathies with the Bardet-Biedl syndrome (BBS), characterized by a constant retinal degeneration, and the microcephaly associated with chorioretinopathy.Using an exomic sequencing approach, we have identified three new genes involved in these rare syndromic retinal diseases and confirmed the implication of a gene in Bardet-Biedl syndrome. The analysis of the retinal phenotypes of a BBS patients’ cohort allowed the description of an atypical retinal phenotype with predominantly cone dysfunction.

京都大学 / 0048 / 新制・課程博士 / 博士(医科学) / 甲第22006号 / 医科博第104号 / 新制||医科||7(附属図書館) / 京都大学大学院医学研究科医科学専攻 / (主査)教授 井上 治久, 教授 伊佐 正, 教授 妻木 範行 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

La microcéphalie est une maladie neurologique du nouveau-né qui se traduit par une circonférence réduite de la tête, une déficience intellectuelle et des défauts anatomiques du cerveau. La microcéphalie peut être la conséquence d’une infection, de stress environnementaux ou de mutations génétiques.Le cerveau commence à se former dès la cinquième semaine de grossesse et est majoritairement constitué de cellules souches neuronales, cellules qui conservent une capacité a se reproduire a l’identique sans se spécialiser. Cette première phase de prolifération est importante pour générer suffisamment de cellules. Suit une phase de différenciation, durant laquelle les cellules préalablement formées se différencient en deux groupes : les neurones, qui permettent de partager l’information grâce à des influx électriques, et les cellules gliales, qui soutiennent activement les fonctions des cellules neuronales.Je m’intéresse à un gène en particulier, KNL1, muté chez certains patients microcéphales. Grace aux nouvelles techniques d’édition du génome, j’ai reproduit la mutation retrouvée chez les patients dans des cellules souches pluripotentes humaines. En utilisant un modèle tridimensionnel (mini-cerveaux en culture), à partir de cellules souches neuronales, j’ai analysé de manière quantitative les étapes-clés de développement: les phases de prolifération et de différenciation.Mes travaux de recherche ont montré que les cellules souches neuronales portant la même mutation que les patients prolifèrent moins, réduisant le nombre de cellules initiales nécessaires au développement cérébral normal. Par ailleurs, les cellules souches neuronales se différencient prématurément en neurones et cellules gliales, ce qui réduit davantage le nombre le nombre final de cellules. Cette hypothèse a été confirmée par l’utilisation du modèle tridimensionnel, ou les mini-cerveaux sont plus petits que la normale.Cette étude est essentielle non seulement pour comprendre le développement de la maladie, mais également pour comprendre les étapes clés du développement du cerveau humain, et ne pourrait pas être mener à bien sur des modèles animaux. En outre, l’utilisation de cellules souches induites nous permet de ne pas utiliser de cellules embryonnaires, si nécessaire pour raisons d’éthique. / Microcephaly is a neurological condition, resulting in patients having a small head circumference, intellectual impairment and brain anatomical defects. A pre-requisite for achieving a better understanding of the cellular events that contribute to the striking expansion of the human cerebral cortex is to elucidate cell-division mechanisms, which likely go awry in microcephaly. Most of the mutated genes identified in microcephaly patient encode centrosomal protein, KNL1 is the only gene that encodes a kinetochore protein, it plays a central role in kinetochore assembly and function during mitosis. While the involvement of centrosome functions is well established in the etiology of microcephaly, little is known about the contribution of KNL1.In an attempt to assess the role of KNL1 in brain development and its involvement in microcephaly, we generated isogenic human embryonic stem cell (hESC) lines bearing KNL1 patient mutations using CRISPR/Cas9-mediated gene targeting. We demonstrated that the point mutation leads to KNL1 reduction in neural progenitors. Moreover, mutant neural progenitors present aneuploidy, an increase in cell death and an abrogated spindle assembly checkpoint. Mutant fibroblasts, derived from hESC, do not have a reduced expression of KNL1 and do not present any defect in cell growth or karyotype, which highlight a brain-specific phenotype.The subsequent differentiation of mutant neural progenitors into two-dimensional neural culture leads to the depletion of neural progenitors in the favor of premature differentiation. We developed a three-dimensional neural spheroids model from neural progenitors and reported a reduced size of mutant neural spheroids, compare to control. Lastly, using knockdown and rescue assays, we proved that protein level of KNL1 is responsible of the premature differentiation and the reduced size.These data suggest that KNL1 has a brain-specific function during the development. Changes in its expression might contribute to the brain phenotypic divergence that appeared during human evolution.

No description available.

Microcephaly is a debilitating condition in which children are born with small brains. It can be caused by a variety of factors including maternal infection, harmful substance exposure, and genetic mutation. Cerebral cortical development is often severely disrupted in human microcephaly patients. In order to form the billions of neurons which exist in the cortex, efficient and correct neural progenitor division, differentiation, and migration are key. As the center of higher brain function in mammals, reduction in cortical mass is associated with the developmental delays that are symptomatic of microcephaly. Recently, a number of microcephaly causes have been linked to P53-mediated apoptosis of neural cells. The tumor suppressor protein P53 is upregulated in response to mitotic cycle stress, and its activation can trigger cell cycle arrest or apoptotic cell death. In microcephaly, P53 can become activated by mitotic stress and trigger apoptosis to cause the loss of cortical cell numbers that leads to microcephaly. Microcephaly has often been linked to mutations in mitotic proteins that alter neural progenitor division. However, the apical polarity complex Protein Associated with Lin-7 1 (PALS1) – known as membrane palmitoylated protein (MPP)5 in people – has recently been implicated in human microcephaly. PALS1 is integral to establishing polarity in neural progenitors. Deletion of Pals1 in mouse models has also resulted in microcephaly characterized by smaller brains and a global reduction in cortical cell numbers. Interestingly, a cellular phenomenon known as entosis can be caused by polarity disruptions in epithelial cells, and P53 activation has been shown to cause entosis in MDCK cell culture. While entosis is mainly associated with cancer cells, it is a form of competitive cell cannibalism that can eliminate unfit cells from a population. The loss of PALS1 from the developing cortex is known to result in apical polarity complex disruption and microcephaly in mouse models. However, the mechanism by which the loss of PALS1 results in cortical abrogation has yet to be determined. In Chapter 1 of this dissertation, I begin by reviewing cortical development. The normal progression of cortical cells from neural progenitors to fully differentiated neurons is explained in detail. Neural progenitor mitosis in particular is addressed in detail. Furthermore, an overview of microcephaly is provided to address the similarities between known causes of microcephaly. Next, I review the polarity complex proteins and their roles in cortical development. I compare and contrast the cortical phenotypes that have been described when each of the polarity complex proteins has been genetically deleted from the mouse cortex. I go on to review studies that have shown P53-mediated apoptosis in microcephaly in order to address the phenotypic features of microcephaly that are or are not caused by P53 activation. Finally, I provide a brief history of entosis. As a newly discovered cellular process in neural progenitors, the overview of entosis highlights what is known about cell cannibalism and the contexts in which it occurs. Following this background, I describe the experimental aims, hypotheses, and methods for this project in Chapter 2. In Chapter 3, I describe our investigation of three human patients with mutations in the Pals1 gene. One of the patients, possessing a heterozygous de novo nonsense mutation in Pals1 (or MPP5), was diagnosed with microcephaly. In order to model this patient’s phenotype, we generated a heterozygous conditional knockout of Pals1 from the entire mouse nervous system with Nestin-Cre. Through behavioral analysis of these mice, I demonstrate that they are hyperactive and blind, mimicking the microcephaly patient’s symptoms. Furthermore, via analysis of the mouse cortex, I show that heterozygous deletion of Pals1 results in severe microcephaly in mice with a global reduction in cortical cell numbers at both adult and embryonic stages. Importantly, I determine that Pals1 deletion does not result in proliferation or migration defects in the mouse cortex. Instead, loss of PALS1 results in massive apoptotic cell death that affects every cell type produced in the developing cortex. In Chapter 4, I detail our investigation into the mechanism underlying cell death in the PALS1-deficient cortex. By studying dividing neural progenitors at the apical surface in both Emx1-Cre and hGFAP-Cre drive Pals1 conditional knockout models, I demonstrate an as yet undescribed neural progenitor phenotype called entosis. As has been shown in cancer cells, neural progenitor entosis is dynamic and reliant on Rho-ROCK activity to occur. Furthermore, entosis produces observable cell-in-cell structures that persist through outer cell division and cause mitotic delay. I go on to demonstrate P53 activation in Pals1 deficient mouse cortices, and show that genetic deletion of Trp53 significantly rescues microcephaly. Trp53 deletion significantly restores all cortical cell types in addition to ameliorating entosis and mitotic length. This study suggests that P53 activation is a major mechanism by which PALS1 loss results in microcephaly. Overall, these studies show that deletion of Pals1 in mice can mimic microcephaly found in a human patient with a Pals1 mutation. Furthermore, PALS1 loss promotes P53-mediated cortical cell apoptosis. These studies provide the first description of entosis in neural progenitors, and suggest that entosis could be a mechanism for unfit cell removal in the developing cortex. Furthermore, I provide evidence that ROCK inhibition can fully rescue the presence of entosis in PALS1-deficient neural progenitors, and that genetic deletion of Trp53 significantly restores microcephaly pathology after PALS1 loss. These studies open up a field of research into the causes and effects of entosis in neural progenitors, and provide further evidence that apoptotic cell death in microcephaly is largely mediated by P53 activation. / Biomedical Sciences

Un des aspects les plus marquants de l'évolution des grands singes est l'augmentation relative du volume du cerveau, et en particulier du néocortex, qui culmine chez Homo sapiens. La microcéphalie primaire est une anomalie congénitale du développement cérébral humain caractérisée par un cerveau normalement formé mais de petit volume. Il en existe une forme isolée, non syndromique, dont la majorité des cas sont d'origine génétique et transmis sur le mode autosomique récessif (MCPH), qui constituent donc un modèle génétiquement simple qui résulte de l'altération d'un seul gène, essentiel dans le développement volumique du cerveau. Une consanguinité parentale est présente dans la majorité des cas, ce qui permet une approche puissante de localisation génomique de la mutation responsable, nommée cartographie d'homozygotie. A ce jour, huit gènes causant cette anomalie ont déjà été identifiés :BRIT1 (MCPH1), ASPM (MCPH5), CDK5RAP2 (MCPH3) et CENPJ (MCPH6), et plus récemment, STIL (MCPH7), CEP152 (MCPH9), WDR62 (MCPH2) et CEP135 (MCPH8). Tous ces gènes jouent un rôle au niveau du cycle cellulaire. Nous avons tenté, au cours de ce doctorat, d’identifier et de caractériser un nouveau gène du locus MCPH4 cartographié au laboratoire et situé sur le bras long du chromosome 15. <p>Dans trois familles MCPH4 originaires de villages voisins du Maroc rural, nous avons affiné la zone de liaison à un segment de 3,7cM, contenant un haplotype commun sur une longueur de 2,7cM suggérant un déséquilibre de liaison autour d’une mutation ancestrale. Le LOD score combiné dans les trois familles était supérieur à 6. Parmi les gènes contenus dans cette région, nous avons sélectionné des candidats que nous avons ensuite analysés par séquençage direct de l’ADN de nos patients. Parmi ces gènes, CASC5 présentait un variant, homozygote chez nos patients, hétérozygote chez leurs parents sains et absent chez 150 contrôles non apparentés. Nous avons utilisé la technologie 454 de séquençage à haut débit de Roche pour séquencer les gènes de l’intervalle de 2.7Mb en une fois. Parmi les mutations identifiées, nous n’avons trouvé qu’une seule variation exonique inconnue qui correspondait à la variation faux-sens déjà identifiée dans le gène CASC5. CASC5 est une protéine centromérique requise pour l’alignement des chromosomes à la métaphase et pour le point de contrôle métaphasique de la progression mitotique. Il était donc potentiellement un très bon candidat causal de la microcéphalie primaire. CASC5 lie directement MIS12, BUB1, BUBR1 et Zwint-1, et fait partie du réseau KMN du kinétochore. Il est nécessaire à l’ancrage des centromères chromosomiques au fuseau mitotique, et est requis pour le contrôle du cycle cellulaire au niveau du Spindle-Assembly Checkpoint.<p>Nous avons ensuite confirmé que la mutation génère un défaut d’épissage chez nos patients consistant en la perte partielle de l’exon 18 dans l’ARNm. La perte de cet exon conduit à un déphasage du cadre de lecture provoquant l’apparition d’un codon STOP prématuré dans l’exon 19. Ceci prédit donc la formation d’une protéine tronquée, ou absente après dégradation par le mécanisme cellulaire de dégradation des ARNm non-sens. Par Western-Blotting nous avons pu révéler, en lignée lymphoblastoïdes, la protéine CASC5 endogène chez tous nos patients, y compris, à notre surprise, chez les sujets atteints. <p>Il est décrit dans la littérature qu’un knockdown de CASC5 provoque un mauvais alignement des chromosomes, une entrée prématurée en mitose et la formation de micronoyaux, conséquence d’un mauvais alignement des chromosomes pendant la métaphase. Les différentes études menées sur le phénotype cellulaire de nos patients en lignées lymphoblastoïdes n’ont pu révéler ces défauts. Notre hypothèse est que l’allèle muté est hypomorphe et que le phénotype cellulaire décrit en boites de culture ne s’observerait in vivo que dans certaines cellules du cerveau en cours de développement.<p>En parallèle de ces travaux, nous avons également contribué à l’identification de la cause d’une microcéphalie primaire syndromique, associée à un diabète insulino-requérant précoce, tansmis sur le mode récessif autosomique et identifié dans une famille d’origine marocaine. Notre laboratoire avait localisé la mutation dans une région de 3 cM du chromosome 4. Parmi les 39 gènes compris dans cette région, nous en avons sélectionné et séquencé plusieurs. Aucun n’a cependant montré de mutation. Un séquençage de l'exome complet de l’un de nos patients, a permis de mettre en évidence une mutation non-sens homozygote dans un gène de l’intervalle critique de liaison. La mutation ségrège avec le phénotype autosomique récessif chez les malades, leurs parents et leurs germains asymptomatiques. L’abondance du transcrit de ce gène a été mesurée en lignées lymphoblastoïdes de patients :il est présent en quantité similaire chez les patients et chez un contrôle non apparenté. <p>En conclusion, notre travail a permis l’identification d’un nouveau gène muté chez des patients atteints de microcéphalie primaire, CASC5, avec un haut degré de preuve de causalité de cette mutation, impliquant ainsi une protéine du réseau KMN du kinétochore dans le développement volumique du cerveau humain. Nous avons par ailleurs contribué à l’identification d’un nouveau gène causant microcéphalie primaire et diabète juvénile, dont le mécanisme biologique est en cours d’investigation.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Submitted by Rosina Valeria Lanzellotti Mattiussi Teixeira (rosina.teixeira@unisantos.br) on 2018-09-03T19:28:21Z No. of bitstreams: 1 Simone da Silva Cordeiro Davi.pdf: 573881 bytes, checksum: cc2dbc54a06141aa2dc5ba8dffd57d3b (MD5) / Made available in DSpace on 2018-09-03T19:28:21Z (GMT). No. of bitstreams: 1 Simone da Silva Cordeiro Davi.pdf: 573881 bytes, checksum: cc2dbc54a06141aa2dc5ba8dffd57d3b (MD5) Previous issue date: 2018-08-14 / Introdução: O surto da infecção pelo Zika Vírus e os nascimentos de crianças com a Síndrome Congênita do ZIKV com associação a microcefalia desencadeou uma série de desafios a serem enfrentados pelos serviços de saúde e famílias. No contexto familiar, as mudanças decorridas desde a chegada de uma criança que necessita de cuidados especiais às percepções e significados construídos acerca da Síndrome e sua repercussão nas práticas de cuidado com a criança ainda são desconhecidos. Objetivo: Analisar o significado e repercussões da Síndrome Congênita ZIKV sobre as práticas de cuidado em saúde para mães de crianças acometidas pela Síndrome no contexto da epidemia do ZIKV no sertão da Paraíba. Método: Trata-se de uma pesquisa qualitativa, em que foram entrevistadas, no período outubro de 2017 a fevereiro de 2018, 8 mães de crianças com o diagnóstico de Síndrome Congênita do ZIKV com associação a microcefalia confirmados no contexto da epidemia ZIKV e que possuem diagnóstico confirmado. Para a delimitação do número de participantes, utilizou-se como critério a saturação dos dados. Utilizou-se como coleta dos dados a entrevista semiestruturada, sendo feitas análises por meio da Análise de Conteúdo sistematizada por Bardin, em que foram identificadas três categorias referentes a relação da mãe com o diagnóstico, com o tratamento e consigo mesma. Resultados: Os diagnósticos de Síndrome Congênita do ZIKV das crianças desta pesquisa aconteceram tanto no período gestacional quanto após os nascimentos das crianças, gerando nas mães sentimentos de angústia e receio, e em algumas mães a rejeição à criança, desenvolvendo sentimento de insegurança e medo por não saberem exatamente do que se tratava e as repercussões em suas vidas e na vida do bebê. Os significados maternos acerca do diagnóstico de microcefalia refletiram na dedicação de suas vidas para as crianças, pois as mães, na maioria das vezes, abandonaram suas vidas profissionais e sociais em função de seus filhos, apresentando baixa autoestima. Quanto aos cuidados recebidos pela criança nos serviços de atenção à saúde, as mães apresentam percepções sobre a falta de preparação dos profissionais sobre a Síndrome, a longa distância que percorrem para as crianças terem acesso ao tratamento, além da percepção de diferenciação nos atendimentos realizados pelos profissionais de saúde. Considerações Finais: As mães que participaram da pesquisa apresentaram uma elevada sobrecarga acerca dos cuidados com a criança, além de um nível econômico extremamente baixo, interferindo na qualidade dos cuidados prestados à criança e a falta de rede de cuidado público em saúde e suporte psicossocial destinado às mães para o enfrentamento das adversidades que a síndrome propõe. / Introduction: The outbreak of Zika Virus infection and the births of children with ZIKV Congenital Syndrome associated with microcephaly have unleashed a number of challenges to be faced by health services and families. In the family context, the changes that have occurred since the arrival of a child in need of special care, the perceptions and meanings built on the Syndrome and its repercussion on the practices of child care are still unknown. Objective: To analyze the significance and repercussions of the ZIKV Congenital Syndrome on health care practices for mothers of children affected by Syndrome in the context of the ZIKV epidemic in the interior of the state of Paraíba. Method: This is a qualitative study, in the period October 2017 to February 2018, eight mothers of children diagnosed with ZIKV congenital syndrome with an association with microcephaly confirmed in the context of the ZIKV epidemic were interviewed. diagnosis confirmed. For the delimitation of the number of participants, the saturation of the data was used as criterion. The semi-structured interview was used as data collection, in which they were analyzed through the systematization of the Bardin Content Analysis, in which three categories were identified regarding the relation of the mother to the diagnosis, to the treatment and to herself. Results: The diagnosis of congenital ZIKV syndrome occurred both during the gestational period and after the birth of the child, generating in the mothers feelings of anguish and fear, and in some mothers rejection to the child, developing feelings of insecurity and fear for not knowing exactly the and the repercussions on their lives and the life of the baby. The maternal meanings about the diagnosis of microcephaly reflected in the dedication of their lives to the children, in which mothers, most of the time, abandoned their professional and social lives according to their children, presenting low self-esteem. As for the care received by the child in the health care services, the mothers present perceptions about the lack of preparation of the professionals about the Syndrome, the long distance that they cover for the children to have access to the treatment, besides the perception of differentiation in the consultations performed by the Health professionals. Final Considerations: Mothers who participated in the research presented a high overload on child care, as well as an extremely low economic level, interfering with the quality of care provided to children and the lack of a network of public health care and psychosocial support intended mothers to face the adversities that the syndrome proposes.

Introdução: A microcefalia é um sinal clínico associado à heterogeneidade etiológica. As principais causas de microcefalia são as infecções congênitas e as anomalias congênitas. Em 2015, após o surto do zika vírus (ZIKV) e o aumento de casos de microcefalia, o Ministério da Saúde (MS) instituiu notificação compulsória para os recém-nascidos (RN) com microcefalia e/ou alterações do Sistema Nervoso Central (SNC). No Brasil, a distribuição geográfica do ZIKV ocorreu de maneira diferenciada nas regiões norte e sul, sendo que no extremo sul do país houve um menor número de infecções por esse vírus. Assim, o estado do Rio Grande do Sul (RS) tornou-se um local importante para a avaliação sistemática das causas de microcefalia neste país, independente da presença de transmissão continuada do ZIKV. Objetivos: Avaliar e descrever as causas de microcefalia dos RN notificados por microcefalia e/ou alterações do SNC no RS. Métodos: Estudo descritivo dos 162 RN com microcefalia notificada no período de dezembro de 2015 a dezembro de 2016. Destes, 99 casos foram avaliados de forma retrospectiva com base em revisão de banco de dados, e 63 casos foram avaliados de forma prospectiva em ambulatório específico do HCPA-Brasil. As etapas propostas para a avaliação (ou informações coletadas dos bancos de dados) foram: 1) histórico da gestante; 2) exame físico do RN; 3) exames para pesquisa de infecção congênita – toxoplasmose, rubéola, ZIKV e CMV (reação de cadeia da polimerase - PCR ou sorológicos); 4) exames de imagem do SNC; 5) avaliação genética (para os casos com história familiar ou suspeita de alteração genética). As crianças foram avaliadas do nascimento até conclusão diagnóstica, seguimento perdido ou término do estudo. O período de avaliação das crianças não foi superior a quatro meses. Resultados: Noventa e cinco casos (58,6%) apresentavam microcefalia grave, resultando em uma prevalência desta complicação ao nascimento de 6.5/10.000 RN. A causa foi definida em 73 dos 162 casos. Destes eram infecções congênitas 31 casos (19.3%), síndromes genéticas 19 casos (11.7%), e malformação isolada do sistema nervoso central 20 casos (12,4%). E a causa não foi identificada em 89 (54,9%). Dos 31 casos com infecções congênitas, três (9.7%) foram diagnosticados com ZIKV, seis (19.3%) com citomegalovírus, oito (25,8%) com toxoplasmose, e 14 (45.2%) com sífilis congênita. Nenhum caso de rubeola congênita foi diagnosticado e a imunidade adquirida para rubeola das mães dos RN notificados foi de 91.6%. Destes casos 14 (45.1%) apresentaram baixo peso ao nascer e 21 (66.7%) eram pequenos para idade gestacional. A microcefalia grave foi identificada em 12 (38.7%) e 6 59.2% dos casos apresentaram alterações cerebrais, o que reforça a gravidade da ação das doenças infecciosas. Conclusão: Este é o primeiro estudo a avaliar os casos de microcefalia e/ou alterações do SNC durante o surto de ZIKV no RS. A prevalência de casos de ZIKV no RS foi inferior a estados do Nordeste do Brasil. A maioria dos casos de infecção congênita apresentaram lesões neurológicas graves, principalmente os casos de ZIKV, o que pode ocasionar atraso no desenvolvimento neurológico e sequelas nestas crianças ao longo da primeira infância. No entanto, salientamos a importância das demais infecções congênitas e causas desconhecidas associadas à microcefalia no RS, independente da presença de ZIKV. / Introduction: Microcephaly is a clinical sign associated with etiological heterogeneity. The main causes of microcephaly are congenital infections and congenital anomalies. The Ministry of Health (MOH) has instituted compulsory notification for newborns with microcephaly and / or Central Nervous System (CNS) disorders in 2015, following the zika virus (ZIKV) outbreak and the increase in cases of microcephaly. In Brazil, the geographical distribution of ZIKV occurred in a differentiated way in the northern and southern regions, and in the southernmost part of the country there were fewer infections due to this virus. Thus, the state of Rio Grande do Sul (RS) has become an important site for the systematic evaluation of the causes of microcephaly in this country, regardless of the presence of continuous transmission of ZIKV. Objectives: To evaluate and describe the causes of microcephaly of newborns notified by microcephaly and / or CNS changes in RS. Methods: Descriptive study of the 162 newborns with microcephaly reported from December 2015 to December 2016. Of these, 99 cases were retrospectively evaluated based on a database review, and 63 cases were evaluated prospectively in an outpatient clinic specific to HCPA-Brazil. The proposed steps for the evaluation (or information collected from the databases) were: 1) history of the pregnant woman; 2) physical examination of the newborn; 3) screening tests for congenital infection - toxoplasmosis, rubella, ZIKV and CMV (polymerase chain reaction - PCR or serological); 4) imaging studies of the CNS; 5) genetic evaluation (for cases with family history or suspected genetic alteration). The children were evaluated from birth to completion of diagnosis, missed follow-up or termination of the study. The evaluation of them was not more than four months. Results: Ninety-five cases (58.6%) presented severe microcephaly, resulting in a prevalence of this complication at birth of 6.5 / 10,000 newborn. A definite cause was established in 73 of the 162 causes. The leading etiology was congenital infections in 31 cases (19.3%), genetic syndromes in 19 cases (11.7%), and isolated central nervous system malformation in 20 cases (12.4%). Of the 31 cases with congenital infections, three (9.7%) were diagnosed with ZIKV, six (19.3%) with cytomegalovirus, eight (25.8%) with toxoplasmosis, and 14 (45.2%) with congenital syphilis. No case of congenital rubella was diagnosed and the acquired immunity to rubella from the mothers of the newborns was 91.6%. Of these, 14 (45.1%) had low birth 8 weight and 21 (66.7%) were small for gestational age. Severe microcephaly was identified in 12 (38.7%) and 59.2% of the cases presented cerebral alterations, which reinforces the severity of the action of infectious diseases. Conclusion: This is the first study to assess the cases of microcephaly and / or CNS changes during the outbreak of ZIKV in RS. The prevalence of ZIKV cases in RS was lower than in the northeastern states of Brazil. Most cases of congenital infection have severe neurological lesions, especially cases of ZIKV, which can cause delay in neurological development and detectable sequelae in these children throughout their first infancy. However, we emphasize the importance of other congenital infections and unknown causes associated with microcephaly in RS, regardless of the presence of ZIKV.

Introdução: A microcefalia é um sinal clínico associado à heterogeneidade etiológica. As principais causas de microcefalia são as infecções congênitas e as anomalias congênitas. Em 2015, após o surto do zika vírus (ZIKV) e o aumento de casos de microcefalia, o Ministério da Saúde (MS) instituiu notificação compulsória para os recém-nascidos (RN) com microcefalia e/ou alterações do Sistema Nervoso Central (SNC). No Brasil, a distribuição geográfica do ZIKV ocorreu de maneira diferenciada nas regiões norte e sul, sendo que no extremo sul do país houve um menor número de infecções por esse vírus. Assim, o estado do Rio Grande do Sul (RS) tornou-se um local importante para a avaliação sistemática das causas de microcefalia neste país, independente da presença de transmissão continuada do ZIKV. Objetivos: Avaliar e descrever as causas de microcefalia dos RN notificados por microcefalia e/ou alterações do SNC no RS. Métodos: Estudo descritivo dos 162 RN com microcefalia notificada no período de dezembro de 2015 a dezembro de 2016. Destes, 99 casos foram avaliados de forma retrospectiva com base em revisão de banco de dados, e 63 casos foram avaliados de forma prospectiva em ambulatório específico do HCPA-Brasil. As etapas propostas para a avaliação (ou informações coletadas dos bancos de dados) foram: 1) histórico da gestante; 2) exame físico do RN; 3) exames para pesquisa de infecção congênita – toxoplasmose, rubéola, ZIKV e CMV (reação de cadeia da polimerase - PCR ou sorológicos); 4) exames de imagem do SNC; 5) avaliação genética (para os casos com história familiar ou suspeita de alteração genética). As crianças foram avaliadas do nascimento até conclusão diagnóstica, seguimento perdido ou término do estudo. O período de avaliação das crianças não foi superior a quatro meses. Resultados: Noventa e cinco casos (58,6%) apresentavam microcefalia grave, resultando em uma prevalência desta complicação ao nascimento de 6.5/10.000 RN. A causa foi definida em 73 dos 162 casos. Destes eram infecções congênitas 31 casos (19.3%), síndromes genéticas 19 casos (11.7%), e malformação isolada do sistema nervoso central 20 casos (12,4%). E a causa não foi identificada em 89 (54,9%). Dos 31 casos com infecções congênitas, três (9.7%) foram diagnosticados com ZIKV, seis (19.3%) com citomegalovírus, oito (25,8%) com toxoplasmose, e 14 (45.2%) com sífilis congênita. Nenhum caso de rubeola congênita foi diagnosticado e a imunidade adquirida para rubeola das mães dos RN notificados foi de 91.6%. Destes casos 14 (45.1%) apresentaram baixo peso ao nascer e 21 (66.7%) eram pequenos para idade gestacional. A microcefalia grave foi identificada em 12 (38.7%) e 6 59.2% dos casos apresentaram alterações cerebrais, o que reforça a gravidade da ação das doenças infecciosas. Conclusão: Este é o primeiro estudo a avaliar os casos de microcefalia e/ou alterações do SNC durante o surto de ZIKV no RS. A prevalência de casos de ZIKV no RS foi inferior a estados do Nordeste do Brasil. A maioria dos casos de infecção congênita apresentaram lesões neurológicas graves, principalmente os casos de ZIKV, o que pode ocasionar atraso no desenvolvimento neurológico e sequelas nestas crianças ao longo da primeira infância. No entanto, salientamos a importância das demais infecções congênitas e causas desconhecidas associadas à microcefalia no RS, independente da presença de ZIKV. / Introduction: Microcephaly is a clinical sign associated with etiological heterogeneity. The main causes of microcephaly are congenital infections and congenital anomalies. The Ministry of Health (MOH) has instituted compulsory notification for newborns with microcephaly and / or Central Nervous System (CNS) disorders in 2015, following the zika virus (ZIKV) outbreak and the increase in cases of microcephaly. In Brazil, the geographical distribution of ZIKV occurred in a differentiated way in the northern and southern regions, and in the southernmost part of the country there were fewer infections due to this virus. Thus, the state of Rio Grande do Sul (RS) has become an important site for the systematic evaluation of the causes of microcephaly in this country, regardless of the presence of continuous transmission of ZIKV. Objectives: To evaluate and describe the causes of microcephaly of newborns notified by microcephaly and / or CNS changes in RS. Methods: Descriptive study of the 162 newborns with microcephaly reported from December 2015 to December 2016. Of these, 99 cases were retrospectively evaluated based on a database review, and 63 cases were evaluated prospectively in an outpatient clinic specific to HCPA-Brazil. The proposed steps for the evaluation (or information collected from the databases) were: 1) history of the pregnant woman; 2) physical examination of the newborn; 3) screening tests for congenital infection - toxoplasmosis, rubella, ZIKV and CMV (polymerase chain reaction - PCR or serological); 4) imaging studies of the CNS; 5) genetic evaluation (for cases with family history or suspected genetic alteration). The children were evaluated from birth to completion of diagnosis, missed follow-up or termination of the study. The evaluation of them was not more than four months. Results: Ninety-five cases (58.6%) presented severe microcephaly, resulting in a prevalence of this complication at birth of 6.5 / 10,000 newborn. A definite cause was established in 73 of the 162 causes. The leading etiology was congenital infections in 31 cases (19.3%), genetic syndromes in 19 cases (11.7%), and isolated central nervous system malformation in 20 cases (12.4%). Of the 31 cases with congenital infections, three (9.7%) were diagnosed with ZIKV, six (19.3%) with cytomegalovirus, eight (25.8%) with toxoplasmosis, and 14 (45.2%) with congenital syphilis. No case of congenital rubella was diagnosed and the acquired immunity to rubella from the mothers of the newborns was 91.6%. Of these, 14 (45.1%) had low birth 8 weight and 21 (66.7%) were small for gestational age. Severe microcephaly was identified in 12 (38.7%) and 59.2% of the cases presented cerebral alterations, which reinforces the severity of the action of infectious diseases. Conclusion: This is the first study to assess the cases of microcephaly and / or CNS changes during the outbreak of ZIKV in RS. The prevalence of ZIKV cases in RS was lower than in the northeastern states of Brazil. Most cases of congenital infection have severe neurological lesions, especially cases of ZIKV, which can cause delay in neurological development and detectable sequelae in these children throughout their first infancy. However, we emphasize the importance of other congenital infections and unknown causes associated with microcephaly in RS, regardless of the presence of ZIKV.