Etiology of intellectual disability in individuals from special education schools in the south of Brazil.

BACKGROUND: Intellectual Disability (ID) is characterized by significant limitations that affect intellectual functioning, adaptive behavior, and practical skills which directly interfere with interpersonal relationships and the environment. In Western countries, individuals with ID are overrepresented in the health system, often due to associated comorbidities, and its life-time cost places ID as one of the most expensive conditions of all diagnoses in the International Classification of Diseases. Most of the people affected (75%) live in low-income countries, suffer from malnutrition, lack health care, and do not have access to adequate treatment. The aim of this study was to obtain an estimate of the diagnostic status as well as the prevalence of familial ID among individuals with serious (moderate or severe) ID in a region of the State of Santa Catarina, investigating attendees of special education schools of the Florianópolis Macroregion. METHODS: This was a cross-sectional study conducted between August 2011 and August 2014, through a semi-structured screening questionnaire for the collection of relevant developmental, clinical, familial and educational data, applied in an interview to guardians of students of special education schools of the macroregion of Florianópolis. RESULTS: The participant special schools enrolled close to 1700 students during the study period and the questionnaire was applied to 849 (50.5%). The male to female ratio of the participants was 1.39:1. Clear etiologic explanations were relatively scarce (24%); most diagnoses referring only to the type and the degree of impairment and for the majority (61.4%) the cause was unknown. About half were sporadic cases within their families (considering three generations). For 44.2% at least one other case of an ID-related condition in the extended family was mentioned, with 293 (34.5%) representing potential familial cases. CONCLUSION: Here we describe the epidemiological profile, the available diagnostics, etiology, family history and possible parental consanguinity of participants with ID of special education schools in the South of Brazil. The main results show the need for etiological diagnosis and uncover the relevance of potential hereditary cases in a population where consanguineous unions have a relatively low frequency (0,6%) and highlight the need for public health actions.

Copy Number Variations in a Cohort of 420 Individuals with Neurodevelopmental Disorders From the South of Brazil.

Chromosomal microarray (CMA) is now recommended as first tier for the evaluation in individuals with unexplained neurodevelopmental disorders (ND). However, in developing countries such as Brazil, classical cytogenetic tests are still the most used in clinical practice, as reflected by the scarcity of publications of microarray investigation in larger cohorts. This is a retrospective study which analyses the reading files of CMA and available clinical data from 420 patients from the south of Brazil, mostly children, with neurodevelopmental disorders requested by medical geneticists and neurologists for diagnostic purpose. Previous karyotyping was reported for 138 and includes 17 with abnormal results. The platforms used for CMA were CYTOSCAN 750K (75%) and CYTOSCAN HD (25%). The sex ratio of the patients was 1.625 males :1 female and the mean age was 9.5 years. A total of 96 pathogenic copy number variations (CNVs), 58 deletions and 38 duplications, were found in 18% of the patients and in all chromosomes, except chromosome 11. For 12% of the patients only variants of uncertain clinical significance were found. No clinically relevant CNV was found in 70%. The main referrals for chromosomal microarrays (CMA) were developmental delay (DD), intellectual disability (ID), facial dysmorphism and autism spectrum disorder (ASD). DD/ID were present in 80%, facial dysmorphism in 52% and ASD in 32%. Some phenotypes in this population could be predictive of a higher probability to carry a pathogenic CNV, as follows: dysmorphic facial features (p-value = < 0.0001, OR = 0.32), obesity (p-value = 0.006, OR = 0.20), short stature (p-value = 0.032, OR = 0.44), genitourinary anomalies (p-value = 0.032, OR = 0.63) and ASD (p-value = 0.039, OR = 1.94). The diagnostic rate for CMA in this study was 18%. We present the largest report of CMA data in a cohort with ND in Brazil. We characterize the rare CNVs found together with the main phenotypes presented by each patient, list phenotypes which could predict a higher diagnostic probability by CMA in patients with a neurodevelopmental disorder and show how CMA and classical karyotyping results are complementary.

Long contiguous stretches of homozygosity detected by chromosomal microarrays (CMA) in patients with neurodevelopmental disorders in the South of Brazil.

BACKGROUND: Currently, chromosomal microarrays (CMA) are recommended as first-tier test in the investigation of developmental disorders to examine copy number variations. The modern platforms also include probes for single nucleotide polymorphisms (SNPs) that detect homozygous regions in the genome, such as long contiguous stretches of homozygosity (LCSH) also named runs of homozygosity (ROH). LCHS are chromosomal segments resulting from complete or segmental chromosomal homozygosity, which may be indicative of uniparental disomy (UPD), consanguinity, as well as replicative DNA repair events, however also are common findings in normal populations. Knowing common LCSH of a population, which probably represent ancestral haplotypes of low-recombination regions in the genome, facilitates the interpretation of LCSH found in patients, allowing to prioritize those with possible clinical significance. However, population records of ancestral haplotype derived LCSH by SNP arrays are still scarce, particularly for countries such as Brazil where even for the clinic, microarrays that include SNPs are difficult to request due to their high cost. METHODS: In this study, we evaluate the frequencies and implications of LCSH detected by Affymetrix CytoScan® HD or 750 K platforms in 430 patients with neurodevelopmental disorders in southern Brazil. LCSH were analyzed in the context of pathogenic significance and also explored to identify ancestral haplotype derived LCSH. The criteria for considering a region as LCSH was homozygosis ≥3 Mbp on an autosome. RESULTS: In 95% of the patients, at least one LCSH was detected, a total of 1478 LCSH in 407 patients. In 2.6%, the findings were suggestive of UPD. For about 8.5% LCSH suggest offspring from first to fifth grade, more likely to have a clinical impact. Considering recurrent LCSH found at a frequency of 5% or more, we outline 11 regions as potentially representing ancestral haplotypes in our population. The region most involved with homozygosity was 16p11.2p11.1 (49%), followed by 1q21.2q21.3 (21%), 11p11.2p11.12 (19%), 3p21.31p21.2 (16%), 15q15 1q33p32.3 (12%), 2q11.1q12.1 (9%), 1p33p32.3 (6%), 20q11.21q11.23 (6%), 10q22.1q23.31 (5%), 6p22.2p22 (5%), and 7q11.22q11.23 (5%). CONCLUSIONS: In this work, we show the importance and usefulness of interpreting LCSH in the results of CMA wich incorporate SNPs.

Familial mental retardation: a review and practical classification.

Mental retardation (MR) is a definition which comprises a series of conditions whose common feature is an intellectual handicap that develops before the age of 18, afflicting 2-3% of the world's population. The classification of MR into different categories is determined by the extent of the handicap instead of its cause, which often remains unrecognized. Sometimes, MR runs in a family, characterizing familial MR, and those cases permit an in-depth look into the genetic causes and consequences of the problem. However, almost no work is available on the prevalence of familial MR among the registered MR cases, possibly because familial MR is a term with no clear definition. The scope of this work is to review the topic and discuss the implications of different genetic and environmental factors, which characterize particular categories of familial cases, suggesting a practical classification of familial MR, which is important for epidemiologic studies and also for counseling in the clinic. Some of the aspects are discussed under the perspective of a newly-developed country like Brazil.

Familial mental retardation: a review and practical classification / Retardo mental familiar: revisão e classificação prática

Mental retardation (MR) is a definition which comprises a series of conditions whose common feature is an intellectual handicap that develops before the age of 18, afflicting 2-3% of the world's population. The classification of MR into different categories is determined by the extent of the handicap instead of its cause, which often remains unrecognized. Sometimes, MR runs in a family, characterizing familial MR, and those cases permit an in-depth look into the genetic causes and consequences of the problem. However, almost no work is available on the prevalence of familial MR among the registered MR cases, possibly because familial MR is a term with no clear definition. The scope of this work is to review the topic and discuss the implications of different genetic and environmental factors, which characterize particular categories of familial cases, suggesting a practical classification of familial MR, which is important for epidemiologic studies and also for counseling in the clinic. Some of the aspects are discussed under the perspective of a newly-developed country like Brazil.

Retardo mental (RM) é uma definição que compreende uma série de condições cuja característica em comum é um déficit intelectual que se desenvolve antes dos 18 anos, afetando 2-3% da população mundial. A classificação do RM em diferentes categorias é determinada pela gravidade do déficit ao invés de sua causa, que com frequência permanece obscura. O RM pode segregar na família, caracterizando RM familiar, e estes casos permitem um olhar mais aprofundado para as causas genéticas e as consequências do problema. Porém, praticamente não existem dados disponíveis sobre a prevalência do RM familiar dentre os casos registrados, possivelmente por ser um termo sem definição clara. O presente trabalho objetiva rever o tópico e discutir as implicações de diferentes fatores genéticos e ambientais que caracterizam categorias particulares de casos familiares, sugerindo uma classificação prática para o RM familiar, importante para estudos epidemiológicos e também na clínica, para aconselhamento. Alguns dos aspectos são discutidos na perspectiva de um país emergente, como o Brasil.

Inflammatory cytokines in vitro production are associated with Ala16Val superoxide dismutase gene polymorphism of peripheral blood mononuclear cells.

Obesity is considered a chronic low-grade inflammatory state associated with a chronic oxidative stress caused by superoxide production (O(2)(-)). The superoxide dismutase manganese dependent (SOD2) catalyzes O(2)(-) in H(2)O(2) into mitochondria and is encoded by a single gene that presents a common polymorphism that results in the replacement of alanine (A) with a valine (V) in the 16 codon. This polymorphism has been implicated in a decreased efficiency of SOD2 transport into targeted mitochondria in V allele carriers. Previous studies described an association between VV genotype and metabolic diseases, including obesity and diabetes. However, the causal mechanisms to explain this association need to be more elucidated. We postulated that the polymorphism could influence the inflammatory response. To test our hypothesis, we evaluated the in vitro cytokines production by human peripheral blood mononuclear cells (PBMCs) carrier's different Ala16Val-SOD2 genotypes (IL-1, IL-6, IL-10, TNF-α, IFN-γ). Additionally, we evaluated if the culture medium glucose, enriched insulin, could influence the cytokine production. Higher levels of proinflammatory cytokines were observed in VV-PBMCs when compared to AA-PBMCs. However, the culture medium glucose and enriched insulin did not affect cytokine production. The results suggest that Ala16Val-SOD2 gene polymorphism could trigger the PBMCs proinflammatory cytokines level. However, discerning if a similar mechanism occurs in fat cells is an open question.

Antioxidant deficit in gills of Pacific oyster (Crassostrea gigas) exposed to chlorodinitrobenzene increases menadione toxicity.

Disturbances in antioxidant defenses decrease cellular protection against oxidative stress and jeopardize cellular homeostasis. To knock down the antioxidant defenses of Pacific oyster Crassostrea gigas, animals were pre-treated with 1-chloro-2,4-dinitrobenzene (CDNB) and further challenged with pro-oxidant menadione (MEN). CDNB pre-treatment (10 µM for 18 h) was able to consume cellular thiols in gills, decreasing GSH (53%) and decrease protein thiols (25%). CDNB pre-treatment also disrupted glutathione reductase and thioredoxin reductase activity in the gills, but likewise strongly induced glutathione S-transferase activity (270% increase). Surprisingly, hemocyte viability was greatly affected 24 h after CDNB removal, indicating a possible vulnerability of the oyster immune system to electrophilic attack. New in vivo approaches were established, allowing the identification of higher rates of GSH-CDNB conjugate export to the seawater and enabling the measurement of the organic peroxide consumption rate. CDNB-induced impairment in antioxidant defenses decreased the peroxide removal rate from seawater. After showing that CDNB decreased gill antioxidant defenses and increased DNA damage in hemocytes, oysters were further challenged with 1 mM MEN over 24 h. MEN treatment did not affect thiol homeostasis in gills, while CDNB pre-treated animals recovered GSH and PSH to the control level after 24 h of depuration. Interestingly, MEN intensified GSH and PSH loss and mortality in CDNB-pre-treated animals, showing a clear synergistic effect. The superoxide-generating one-electron reduction of MEN was predominant in gills and may have contributed to MEN toxicity. These results support the idea that antioxidant-depleted animals are more susceptible to oxidative attack, which can compromise survival. Data also corroborate the idea that gills are an important detoxifying organ, able to dispose of organic peroxides, induce phase II enzymes, and efficiently export GSH-CDNB conjugates.

A study of the relative importance of the peroxiredoxin-, catalase-, and glutathione-dependent systems in neural peroxide metabolism.

Cells are endowed with several overlapping peroxide-degrading systems whose relative importance is a matter of debate. In this study, three different sources of neural cells (rat hippocampal slices, rat C6 glioma cells, and mouse N2a neuroblastoma cells) were used as models to understand the relative contributions of individual peroxide-degrading systems. After a pretreatment (30 min) with specific inhibitors, each system was challenged with either H2O2 or cumene hydroperoxide (CuOOH), both at 100 µM. Hippocampal slices, C6 cells, and N2a cells showed a decrease in the H2O2 decomposition rate (23-28%) by a pretreatment with the catalase inhibitor aminotriazole. The inhibition of glutathione reductase (GR) by BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea) significantly decreased H2O2 and CuOOH decomposition rates (31-77%). Inhibition of catalase was not as effective as BCNU at decreasing cell viability (MTT assay) and cell permeability or at increasing DNA damage (comet test). Impairing the thioredoxin (Trx)-dependent peroxiredoxin (Prx) recycling by thioredoxin reductase (TrxR) inhibition with auranofin neither potentiated peroxide toxicity nor decreased the peroxide-decomposition rate. The results indicate that neural peroxidatic systems depending on Trx/TrxR for recycling are not as important as those depending on GSH/GR. Dimer formation, which leads to Prx2 inactivation, was observed in hippocampal slices and N2a cells treated with H2O2, but not in C6 cells. However, Prx-SO3 formation, another form of Prx inactivation, was observed in all neural cell types tested, indicating that redox-mediated signaling pathways can be modulated in neural cells. These differences in Prx2 dimerization suggest specific redox regulation mechanisms in glia-derived (C6) compared to neuron-derived (N2a) cells and hippocampal slices.

A patogênese genética e molecular da síndrome de Angelman / The genetic and molecular pathogenesis of the Angelman syndrome

Objetivo: Fornecer uma revisão atualizada em língua portuguesa sobre a síndrome de Angelman, com ênfase nos mecanismos genéticos e moleculares dessa patologia, uma causa de deficiência mental severa que em alguns casos pode apresentar recorrência familiar. Método: Foi feita uma revisão bibliográfica utilizando a base de dados do PubMed, tendo como critérios de busca o termo "Angelman syndrome" isoladamente e combinado com "UBE3A", "clinical", "genetics" e "molecular" no título dos artigos. Dentre esses, foram selecionados artigos de revisão e artigos originais sobre a fisiopatologia da síndrome, com ênfase nos últimos dez anos. Resultados: Utilizando-se "Angelman syndrome" na busca, apareceram cerca de 1.100 artigos, incluindo 240 de revisão. Nos últimos dez anos são mais de 600 artigos, aproximadamente 120 de revisão, 50 por cento dos quais publicados nos últimos cinco anos. Na base de dados SciELO, são apenas nove artigos sobre a síndrome, dos quais três em português e nenhum artigo atual de revisão. Conclusão: Após ter sido uma das principais causas que atraíram atenção ao estudo e ao entendimento dos mecanismos do imprinting genômico, a síndrome de Angelman está agora se revelando como uma patologia das sinapses. Apesar de o entendimento da fisiopatologia molecular da síndrome de Angelman ainda estar longe de ser compreendida, seu estudo está fornecendo uma visão extraordinária sobre os mecanismos que regem a plasticidade sináptica, novamente atraindo a atenção de pesquisadores que trabalham na fronteira do conhecimento.

Objective: The aim of this work is to provide an actualized review in Portuguese language of the main clinical and behavioral features and in particular of the genetic and molecular aspects of Angelman syndrome, a cause of severe intellectual disability, which in rare cases can be recurrent in the family. Method: This paper is a literature review that used as a source of research, scientific papers with the terms "Angelman syndrome" or combined with UBE3A, clinical, genetics, and molecular in their title, retrieved trough the PubMed database. Among those, mainly review articles and original papers about cellular and molecular aspects of the pathology were selected, prioritarily, those published in the last ten years. Results: The term Angelman syndrome retrieved about 1100 papers, including close to 240 review articles. During the last ten years there were over 600 publications, with approximately 120 reviews, 50 percent of whom published in the last five years. The SciELO database was also searched and nine publications about the syndrome were found, three of which in Portuguese and no recent review article. Conclusion: After being one of the main causes to attract attention and stimulate studies to unravel the mechanisms of the genetic imprinting, Angelman syndrome is again in the spotlight because it is revealing itself as pathology of synaptic dysfunction. Albeit still long from understood, the molecular and cellular alterations in Angelman syndrome are allowing an extraordinary insight into the mechanisms which control synaptic plasticity.

Gender effects of acute malathion or zinc exposure on the antioxidant response of rat hippocampus and cerebral cortex.

Gender is one of the most important factors in mammalian development and response to exogenous agents. Although there is increasing evidence that health effects of toxic xenobiotics differ in prevalence or are manifested differently in male and female, the molecular mechanisms related to these events remain unclear. In order to investigate the possible influence of gender, male and female Wistar rats from the same litter were exposed to zinc chloride (5 mg/kg, i.p.) or malathion (250 mg/kg, i.p.) 24 hr prior to the analyses of biochemical parameters related to the cholinergic and glutathione-antioxidant systems in cerebral cortex and hippocampus. After treatments, acetylcholinesterase (AChE) activity was reduced in the hippocampus and cerebral cortex of male and female rats treated with malathion, but the effect was more pronounced in the male group. Glutathione reductase (GR) and γ-glutamyl-transpeptidase activities were reduced in the hippocampus of males and females and a gender-specific effect of malathion was seen for glutathione S-transferase (GST), which was decreased only in male hippocampus and cortex, and for male cortical GR. Zinc chloride treatment decreased AChE activity in male and female cerebral cortex, with no obvious effect in the hippocampus. Male-specific antioxidant-related enzyme activity reductions were seen after zinc treatment for cortical GR, GST, glutathione peroxidase and glucose-6-phosphate dehydrogenase; and hippocampal GR. These results clearly demonstrate a greater detrimental effect on antioxidant-related enzyme activities in male hippocampus and cerebral cortex when rats were acutely exposed to malathion and zinc, demonstrating that the research on gender-related differences in health effects caused by xenobiotic and/or essential elements requires further attention.