Caracterização fenotípica das epilepsias geneticamente determinadas diagnosticadas pelo sequenciamento de nova geração / Phenotypic characterization of genetically determined epilepsies diagnosed by next-generation sequencing

Nos últimos anos, o emprego na prática clínica de painéis genéticos e do sequenciamento do exoma e do genoma permitiu o diagnóstico em pacientes sem uma etiologia definida, principalmente nas Encefalopatias Epilépticas e do Desenvolvimento (EEDs). A identificação das formas de epilepsia geneticamente determinadas permite caracterizar melhor sua história natural e orientar o tratamento, ao mesmo tempo em que propicia o aconselhamento genético. O objetivo do estudo foi descrever o fenótipo de indivíduos com epilepsia geneticamente determinada com variantes patogênicas ou provavelmente patogênicas, previamente identificadas pelo NGS. Foram incluídos pacientes até a idade de 18 anos, acompanhados por serviços de Neurologia Infantil e/ou de Genética Médica no estado do Rio de Janeiro, provenientes de hospitais públicos ou de clínicas privadas. O estudo, de natureza descritiva e transversal, foi realizado através da análise de uma amostra de conveniência. No período de abril de 2020 até dezembro de 2021, foram incluídos 75 pacientes, cujo diagnóstico etiológico foi relacionado a 53 genes diferentes. O tipo de sequenciamento de nova geração realizado foi exoma em 56 (74,6%) pacientes, painel genético em 18 (24%) e genoma em um (1,7%). Em relação ao padrão de herança dos 53 genes, 50 (67%) pacientes apresentavam variantes deletérias em genes de herança autossômica dominante (AD), dez (13%) em genes com herança autossômica recessiva (AR), 12 (16%) em genes com o padrão dominante ligado ao X (XD) e 3 (4%) em genes com herança recessiva ligada ao X (XR). O teste em trio foi realizado em 37 pacientes (49,3%) e 33 pacientes apresentaram variantes de novo. O tipo de variante mais frequente foi a missense, seguida pelas variantes frameshift, variantes em regiões de sítio de splicing, deleções in-frame e variantes nonsense. A média de idade do diagnóstico da epilepsia foi de 18 meses, variando entre o primeiro dia de vida até 12 anos. Diagnóstico de EED foi estabelecido em 97,3% pacientes (N=73), na média de idade de 3 anos e 1 mês, e 36 pacientes apresentam uma síndrome epiléptica específica, sendo as mais comuns as Síndromes de West e de Lennox-Gastaut. O padrão de herança de maior frequência no grupo estudado foi AD. Os genes mais frequentes encontrados na nossa amostra foram: genes com herança AD: SCN8A (8%), STXBP1 (8%), KCNQ2 (6,6%), KCNT1 (4%); ligada ao XD: CDKL5 (4%); PCDH19 (4%); e AR: RARS2 (2,6%). O maior número de pacientes está associado a genes que sintetizam canais iônicos voltagem-dependentes (N=19/25,3%) e os genes mais frequentes foram, sucessivamente: SCN8A, KCNQ2, KCNT1, KCNA2. Na nossa amostra, somente dois pacientes conseguiram realizar o exame pelo SUS. O tempo médio de espera para realização do NGS foi de 8 meses. O conhecimento e a interpretação dos resultados dos testes genéticos moleculares têm evoluído de maneira substancial. Disponibilizar o NGS de forma universal para pacientes com suspeita de epilepsia de origem genética, permitirá o diagnóstico de um maior número de pacientes, a identificação de casos atípicos e a adequação terapêutica.

In recent years, the use in clinical practice of genetic panels, exome and genome sequencing has allowed the diagnosis in patients without a defined etiology, mainly in epileptic and developmental encephalopathies (EED). The identification of genetically determined forms of epilepsy makes it possible to better characterize its natural history, guide treatment and provide genetic counseling. The aim of the study was to describe the phenotype of individuals with genetically determined epilepsy with pathogenic or probably pathogenic variants, previously identified by NGS. Patients up to the age of 18 years, followed by Child Neurology and/or Medical Genetics services in the State of Rio de Janeiro, from Public Hospitals or private clinics were included. The study was descriptive and transversal, through the analysis of a convenience sample. From April 2020 to December 2021, 75 patients were included, whose etiological diagnosis was related to 53 different genes. The type of next-generation sequencing performed was exome in 56 (74.6%) patients, genetic panel in 18 (24%) and 1 (1.7%) performed the genome. Regarding the inheritance pattern of the 53 genes, 50 (67%) patients had deleterious variants in genes of autosomal dominant inheritance (AD), 10 (13%) in genes with autosomal recessive inheritance (AR), 12 (16%) with dominant pattern X-linked (XD) and 3 (4%) with X-linked recessive inheritance (XR). Trio testing was performed in 37 patients (49.3%) and 33 patients have de novo variants. The most frequent type of variant was missense, followed by frameshift variants, variants in splicing site regions, in- frame and nonsense variants. The mean age of epilepsy diagnosis was 18 months, ranging from the first day of life to 12 years. Diagnosis of DEE was established in 97.3% patients (N=73), with a mean age of 3 years and 1 month and 36 patients presented a specific epileptic syndrome, the most common being West syndrome and Lennox- Gastaut. The most frequent inheritance pattern in the studied group was AD. The most frequent genes found in our sample were: genes with AD inheritance: SCN8A (8%), STXBP1 (8%), KCNQ2 (6.6%), KCNT1 (4%); XD-linked: CDKL5 (4%); PCDH19 (4%); and AR: RARS2 (2.6%). The largest number of patients is associated with genes that synthesize voltage-gated ion channels (N=19/25.3%) and the most frequent genes were successively: SCN8A, KCNQ2, KCNT1, KCNA2. In our sample, only 2 patients were able to perform the exam through the SUS. The mean waiting time for performing the NGS was 8 months. Knowledge and interpretation of molecular genetic test results have evolved substantially. Making NGS universally available in patients suspected of having epilepsy of genetic origin, will allow the diagnosis of a greater number of patients, identification of atypical cases and therapeutic adequacy.

Calcinosis cutis congénita tumoral asociada con encefalopatía epiléptica infantil temprana con variante patogénica en el gen FGF12 / Tumorous congenital calcinosis cutis associated with early childhood epileptic encephalopathy with a pathogenic FGF12 gene variant

Resumen Introducción: La calcinosis cutis es el depósito de sales insolubles de calcio en la piel y se clasifica, de acuerdo con su patogénesis, en distrófica, metastásica, idiopática, iatrogénica y calcifilaxis. La calcinosis idiopática se presenta en pacientes sanos y es asintomática; incluye la calcinosis escrotal, la calcinosis nodular de Winer o nódulos calcificados subepidérmicos y la calcinosis tumoral familiar. Esta última es una condición rara que se caracteriza por el depósito de calcio periarticular en pacientes normocalcémicos sin conexión al hueso. Caso clínico: Paciente de sexo masculino de 5 meses de edad, quien al séptimo día de vida fue hospitalizado por ictericia multifactorial, sepsis neonatal tardía y apnea con crisis epilépticas. La evolución fue tórpida, con ingresos hospitalarios por crisis epilépticas de difícil manejo, respuesta parcial a la difenilhidantoína y descontrol electrolítico. Mediante la secuenciación del exoma dirigido se detectó una variante patogénica de sentido equivocado en FGF12 que confirmó el diagnóstico de encefalopatía epiléptica temprana número 47. Además, el paciente presentó dermatosis congénita diseminada a las extremidades inferiores con afección en muslos, asintomática, bilateral y simétrica, constituida por hipopigmentación y fóveas duras a la palpación profunda. La biopsia mostró calcificación distrófica. Conclusiones: Se presenta el caso de un lactante con calcinosis cutis congénita profunda asociada con una variante patogénica en el gen FGF12 y con encefalopatía epiléptica, situación clínica que, a la fecha, no había sido reportada en la literatura.

Abstract Background: Calcinosis cutis is the deposit of insoluble calcium salts in the skin. It is classified according to its pathogenesis in dystrophic, metastatic, idiopathic, iatrogenic, and calciphylaxis. Idiopathic calcinosis is asymptomatic, occurs in healthy patients, and includes scrotal calcinosis, Winer's nodular calcinosis or subepidermal calcified nodules, and familial tumor calcinosis. The latter is a rare condition characterized by periarticular calcium deposition in normocalcemic patients with no bone connection. Case report: The case of a 5-month-old male patient, who on the seventh day of life was hospitalized for multifactorial jaundice, late neonatal sepsis, and apnea with epileptic seizures is described. His evolution was torpid, with hospital admissions due to epileptic seizures that were difficult to manage with partial response to the use of diphenylhydantoin and electrolyte alterations. By means of exome sequencing directed, a pathogenic variant of wrong direction in FGF12 was detected and the diagnosis of early epileptic encephalopathy number 47 was confirmed. Also, the patient showed disseminated congenital dermatosis to lower extremities affecting thighs, asymptomatic, bilateral and symmetrical, constituted by hypopigmentation and fovea hard to deep palpation. The biopsy showed dystrophic calcification Conclusions: The case of an infant with deep congenital cutis calcinosis associated with a pathogenic variant in the FGF12 gene with epileptic encephalopathy is described. To date, this clinical situation has not been previously reported in the literature.

Rett syndrome: the Brazilian contribution to the gene discovery / Síndrome de Rett: a contribuição brasileira para a descoberta do gene

ABSTRACT A brief history of the syndrome discovered by Andreas Rett is reported in this paper. Although having been described in 1966, the syndrome was only recognized by the international community after a report by Hagberg et al. in 1983. Soon, its importance was evident as a relatively frequent cause of severe encephalopathy among girls. From the beginning it was difficult to explain the absence of male patients and the almost total predominance of sporadic cases (99%), with very few familial cases. For these reasons, it was particularly difficult to investigate this condition until 1997, when a particular Brazilian family greatly helped in the final discovery of the gene, and in the clarification of its genetic mechanism. Brief references are made to the importance of the MECP2 gene, 18 years later, as well as to its role in synaptogenesis and future prospects.

RESUMO Uma breve história de uma síndrome neurológica descoberta por Andreas Rett é relatada neste artigo. Embora tenha ocorrido em 1966, a síndrome só foi reconhecida pela comunidade internacional após um relato de Hagberget al, em 1983. Logo, sua importância ficou evidente como causa relativamente frequente de encefalopatia grave entre as crianças do sexo feminino. Desde o início, foi difícil explicar a ausência de envolvimento de pacientes do sexo masculino e a quase absoluta preponderância de casos esporádicos (99%), com muitos poucos casos familiares. Por essas razões, foi difícil investigar essa condição até 1997, quando uma família brasileira em particular ajudou muito na descoberta final do gene e no esclarecimento de seu mecanismo genético. São feitas referências sucintas à importância do gene MECP2, dezoito anos depois, bem como ao seu papel na sinaptogênese e nas perspectivas futuras.

Encefalopatías epilépticas determinadas genéticamente / Genetically determined epileptic encephalopathies

Las encefalopatías epilépticas es un grupo de síndromes epilépticos caracterizados por el deterioro cognitivo más allá de lo esperado debido a la actividad epiléptica. Se caracterizan por presentar resistencia farmacológica grave, electroencefalogramas profundamente anormales, inicio en la niñez temprana, deterioro neurocognitivo, fenotipo variable y resonancia magnética de cerebro usualmente normal. Frecuentemente estos síndromes están genéticamente determinados. Su diagnóstico correcto y oportuno puede contribuir y guiar el consejo médico y terapia adecuada, influyendo así en el pronóstico a corto, mediano y largo plazo. En este artículo se revisan los hallazgos electroencefalográficos, genéticos y opciones terapéuticas más recomendadas, facilitando así la conducta clínica. Las encefalopatías epilépticas incluidas en este artículos abarcan los síndromes de Ohtahara, encefalopatia mioclónica temprana, epilepsia focal migratoria de la infancia, West, Dravet, estado mioclónico en encefalopatías no progresivas, Doose, Lennox-Gastaut, Landau-Kleffner y epilepsia con espiga-onda continuas durante el sueño de onda lenta.

Epileptic encephalopathies is a group of epileptic syndromes characterized by progressive cognitive impairment beyond the expected for the epilepsy activity. They are characterized by severe pharmaco-resistant epilepsy, severely abnormal electroencephalograms, early-age onset, neurocognitve impairment, variable phenotype and usually normal brain MRI. These syndromes are usually genetically determined. A correct and timely diagnosis could help and guide the medical counselling and the correct therapeutic approach improving the short, medium and long term outcomes. In this article we review the electroencephalographic and genetic findings along with the most recommended therapeutic options facilitating the clinical management. We include the following epileptic encephalopathy syndromes: Ohtahara, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, West, Dravet, non-progressive myoclonic status, Doose, Lennox-Gastaut, Landau-Kleffner and continuous spike-wave during sleep epilepsy.

Novel mutation in MCT8 gene in a Brazilian boy with thyroid hormone resistance and severe neurologic abnormalities / Mutação nova do gene MCT8 em menino Brasileiro com resistência ao hormônio tireioidiano e neuropatia grave

O MCT8 é um transportador celular de hormônios tireoidianos, importante para sua ação e metabolização. Relatamos o caso de um menino com a nova mutação inativadora 630insG no éxon 1 do MCT8. O paciente caracterizou-se por grave comprometimento neurológico (inicialmente com hipotonia global, evoluindo com hipertonia generalizada), crescimento normal nos dois primeiros anos de vida, reduzido ganho ponderal e ausência dos sinais e sintomas típicos de hipotireoidismo. A sua avaliação sérica revelou elevação do T3, redução do T4 total e livre e TSH levemente aumentado. O tratamento com levotiroxina melhorou o perfil hormonal tireoidiano, mas não modificou o quadro clínico do paciente. Esses dados reforçam o conceito de que o papel do MCT8 é tecido-dependente: enquanto os neurônios são altamente dependentes do MCT8, o osso, o tecido adiposo, o músculo e o fígado são menos dependentes do MCT8 e, portanto, podem sofrer as consequências da exposição a níveis séricos elevados de T3.

MCT8 is a cellular transporter of thyroid hormones important in their action and metabolization. We report a male patient with the novel inactivating mutation 630insG in the coding region in exon 1 of MCT8. He was characterized clinically by severe neurologic impairment (initially with global hypotonia, later evolving with generalized hypertonia), normal growth during infancy, reduced weight gain, and absence of typical signs and symptoms of hypothyroidism, while the laboratory evaluation disclosed elevated T3, low total and free T4, and mildly elevated TSH serum levels. Treatment with levothyroxine improved thyroid hormone profile but was not able to alter the clinical picture of the patient. These data reinforce the concept that the role of MCT8 is tissue-dependent: while neurons are highly dependent on MCT8, bone tissue, adipose tissue, muscle, and liver are less dependent on MCT8 and, therefore, may suffer the consequences of the exposition to high serum T3 levels.

Inherited neurodevelopmental brain diseases: applications of homozygosity mapping to identify new genetic causes of disease

The last two decades have seen major advancements in our understanding of some of the most common neurodevelopmental disorders in the field of child neurology. However, in the majority of individual patients, it is still not possible to arrive at a molecular diagnosis, due in part to lack of knowledge of molecular causes of these tremendously complex conditions. Common genetic disorders of brain development include septo-optic dysplasia, schizencephaly, holoprosencephaly, lissencephaly and hindbrain malformations. For each of these disorders, a critical step in brain development is disrupted. Specific genetic diagnosis is now possible in some patients with most of these conditions. For the remaining patients, it is possible to apply gene-mapping strategies using newly developed high-density genomic arrays to clone novel genes. This is especially important in countries like Iran where large family size and marriage between relatives makes these strategies tremendously powerful

Síndrome de Joubert y signo del molar en el conjunto malformativo cerebelo-óculo-renal en dos pacientes / Joubert Syndrome and molar sign in the renal-ocular-cerebelar complex in two patients

El síndrome de Joubert (SJ) es una afección autosómica recesiva caracterizada por taquipnea neonatal episódica, anormalidades oculomotoras (apraxia oculomotora, nistagmus, estrabismo), hipotonía desde el nacimiento con posterior aparición de ataxia, retardo madurativo, deficiencia mental y algunos rasgos faciales distintivos. Es clínicamente heterogéneo presentando algunos pacientes amaurosis congénita de Leber, nefronoptisis y/o enfermedad renal medular quística. Existe igualmente heterogeneidad genética. Las imágenes de resonancia magnética revelan hipoplasia/aplasia de vermis, prominencia y elongación de los pedúnculos cerebelosos superiores y fosa interpeduncular ensanchada, evocando conjuntamente la silueta de una muela o “signo del molar”. También se evidencian alteraciones morfológicas del 4º ventrículo, que adquiere forma de “alas de murciélago”. El SJ es incluido actualmente en el espectro malformativo de síndromes cerebelo-óculo-renales (SCOR). Objetivo: Presentar los casos clínicos de dos pacientes con SJ diagnosticado por hallazgos clínicos y resonancia magnética, y revisar los aportes de las recientes investigaciones genéticas.

Síndrome peri-sylviana: estudo de uma família brasileira com ênfase na modalidade de transmissão genética e espectro clínico / Perisylvian syndrome: report of one Brazilian family with focus on the genetic mode of inheritance and clinical spectrum

Síndrome peri-sylviana (SP) refere-se a diversas manifestações clínicas que podem acompanhar lesões que comprometem a região peri-sylviana ou opercular, podendo ser adquirida, como em acidentes vasculares cerebrais ou encefalites virais, ou ser congênita. A SP congênita pode se manifestar com grande variação clínica e em idades precoces. Com o advento da ressonância magnética (RM) foi possível observar a presença de polimicrogiria (PMG) na região da fissura de Sylvius em diversos pacientes com quadro clínico de SP. O objetivo do presente estudo é analisar e divulgar essa entidade raramente diagnosticada por meio da descrição de uma família. A família em questão compõe-se de cinco indivíduos acometidos, sendo o distúrbio de linguagem a manifestação mais prevalente, ou seja, presente em todos eles. Epilepsia, déficit motor e sinais pseudobulbares (como sialorréia) foram evidenciados no paciente que mostrou maior alteração à RM (PMG difusa). A paciente com PMG parietal posterior e os outros três com RM normais tiveram manifestações clínicas mais sutis. Apesar da maioria das famílias descritas até o momento apresentar transmissão ligada ao cromossomo X, a nossa família sugere transmissão autossômica dominante, já que dois meninos afetados são filhos de homens também acometidos. Os nossos dados reforçam a idéia de que a SP apresenta heterogeneidade genética.

A Novel Missense Mutation of Doublecortin: Mutation Analysis of Korean Patients with Subcortical Band Heterotopia

The neuronal migration disorders, X-linked lissencephaly syndrome (XLIS) and subcortical band heterotopia (SBH), also called "double cortex", have been linked to missense, nonsense, aberrant splicing, deletion, and insertion mutations in doublecortin (DCX) in families and sporadic cases. Most DCX mutations identified to date are located in two evolutionarily conserved domains. We performed mutation analysis of DCX in two Korean patients with SBH. The SBH patients had mild to moderate developmental delays, drug-resistant generalized seizures, and diffuse thick SBH upon brain MRI. Sequence analysis of the DCX coding region in Patient 1 revealed a c.386 C>T change in exon 3. The sequence variation results in a serine to leucine amino acid change at position 129 (S129L), which has not been found in other family members of Patient 1 or in a large panel of 120 control X-chromosomes. We report here a novel c.386 C>T mutation of DCX that is responsible for SBH.

Developmental disorders of activity dependent neuronal plasticity.

A number of neurodevelopmental disorders are caused by defects in activity dependent neuronal plasticity, the process by which neuronal activity shapes developing neuronal circuits. These disorders are caused by genetic mutations or other factors that disrupt intracellular signaling pathways that link the cell surface with the nuclear machinery for gene expression. The signaling pathways disrupted by these disorders are involved in learning, memory and behavior as well as in the synaptic proliferation and pruning that occurs during normal development. Examples of neurodevelopmental disorders that target plasticity include X-linked disorders such as Rett, Fragile-X and Coffin-Lowry Syndromes as well as acquired disorders such as cretinism. Several other X-linked mental retardation syndromes as well as autosomal disorders including neurofibromatosis type 1 and tuberous sclerosis also involve signaling pathways involved in neuronal plasticity. Disruption of neuronal plasticity is a mechanism that may underlie a diverse group of neurodevelopmental disorders.

Sindrome de Van der Knaap: megalencefalia com leucodistrofia: a respeito de dois casos na mesma família / Van Der Knaap syndrome: megalencephaly with leukodystrophy: report of 2 cases in the same family

Relatamos os casos de dois irmãos, com quatro e seis anos de idade, com achados característicos da síndrome de Van Der Knaap. Discutimos os seus aspectos clínicos e radiológicos, assim como suas peculiaridades. Comparamos aos dados da literatura e analisamos os possíveis mecanismos etiopatogênicos envolvidos.

Clonal chromosome abnormalites found in three non-neoplastic proliferative brain lesions

Chromosome analysis was made of brain lesions from three patients which, according to classical histopathological criteria, did not contain tumor cells. In addition to normal cells, we identified abnormal karyotypes with clonal numerical and structural chromosome alterations in at least two independently originated primary cultures from each lesion. Our data suggest that chromosomal aberrations can exist in vivo in non-neoplastic lesions. Other abnormalities may be due to genetic instability manifested only in vitro (culture artifacts) or may already have been present in brain tissue, reflecting previous chromosome damage (as a result of exposure to chemical treatment or enviromental clastogens).