Screening for fragile X syndrome in males from specialized institutions in the northeast region of Brazil.

The objective of this study was to perform a study of fragile X syndrome (FXS) in São Luís, Maranhão, in males residing in five specialized institutions. Two hundred thirty-eight males with intel-lectual disability of unknown etiology participated in this study. Blood samples were processed and stored until DNA extraction. Screening for FMR1 gene mutations was performed using non-isotopic polymerase chain reaction amplification and DNA sequencing using an ABI Prism 3130 automated sequencer. Two individuals (0.84%) were positive for FMR1 mutations. One had a mutation due to expansion of the CGG repeat beyond normal levels and the other had a deletion in exon 1 of the FMR1 gene, which was confirmed by sequencing. Both probands were over 18 years old, which demonstrates the late diagnosis of the condition in these individuals and reinforces the need to implement ef-fective programs for early diagnosis of FXS in the state of Maranhão. We found that FXS might be transmitted in the families of the two indi-viduals bearing the mutation, and that it is important to understand the mutation dynamics to provide better counseling to the family members of these two individuals.

Levels of mannose-binding lectin in individuals with visceral leishmaniasis in the northeast region of Brazil.

Visceral leishmaniasis (VL) is one of the seven priority endemic diseases in the world. The clinical outcome of many infections is not only dependent on the pathogenic organism, but also on the genetic variability of the host susceptibility to infection. Mannose-binding lectin (MBL) is a protein that plays an important role in the innate immune system. The aim of this study was to compare the serum levels of MBL between healthy controls and carriers of VL. The VL cases were recruited randomly from the main hospitals and referral outpatient clinics for VL in São Luís, and from home visits. Determination of MBL protein levels was performed by enzyme-linked immunosorbent assay. Of the 161 patients with VL and the 161 healthy controls, 60.9 and 67.1% had high levels of MBL, respectively. There was no significant difference in MBL levels between cases and controls. Low socioeconomic status and living conditions are conducive to the occurrence of VL. Owing to the small number of existing studies, it is extremely important to conduct further studies on MBL levels and susceptibility to VL, especially in regions where the disease is endemic, such as Maranhão, Brazil.

MicroRNAs: macro challenges on understanding human biological functions and neurological diseases.

MicroRNAS (miRNAs) are a class of endogenously single-stranded non-coding RNA molecules that can negatively modulate the expression of target messenger RNAs by 3' UTR base pairing. During the processing of a miRNA, a network of orchestrated molecular events provides a dynamic manner to posttranscriptionally modulate gene expression. Recent research has demonstrated that although these molecules are small, they are involved in several crucial biological functions, as well as, in a broad spectrum of human diseases. In this review, we highlighted the current knowledge on the miRNA pathway field, focusing on how the disruption of the miRNA-mediated silencing pathways could lead to the pathogenesis of neurological disorders. The potential use of miRNAs as diagnostic/prognostic markers and the possibility of reversing the effects of some miRNA polymorphisms/mutations by promising therapeutics procedures have brought new perspectives into the treatment of human pathologies.

Beta3-adrenergic receptor polymorphism is related to cardiometabolic risk factors in obese Brazilian subjects.

We determined whether ADRbeta3 polymorphism is associated with obesity-related traits in 140 obese patients. Molecular analysis was performed by PCR and RFLP. Individuals carrying the Arg64 allele had a lower waist-to-hip ratio, higher adiponectin and high-density lipoprotein cholesterol levels, and a tendency towards lower blood pressure. In contrast, Trp64/Trp64 carriers were at greater risk for dysmetabolic phenotypes (odds ratio = 2.88, P = 0.03).

Genetic analysis of LRRK2 functional domains in Brazilian patients with Parkinson's disease.

BACKGROUND AND PURPOSE: Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) have been associated with Parkinson's disease (PD), and the majority of the pathogenic variants are located in the ROC and MAPKKK domains. METHODS: Exons 29-31 and 38-44 (ROC and MAPKKK domains) were sequenced in 204 patients with PD, mostly Brazilian. RESULTS: We identified four polymorphisms, a novel silent variant p.R1398R and four substitutions: p.T1410M, p.G2019S, p.Y2189C and the novel variant p.C2139S. CONCLUSIONS: The most prevalent mutation was the p.G2019S (2.4%). We consider that the p.T1410M and the p.Y2189C variants are probably polymorphisms and that the p.C2139S mutation is potentially pathogenic.

Investigation of CBS, MTR, RFC-1 and TC polymorphisms as maternal risk factors for Down syndrome.

Recent evidence shows that almost 92% of the DS children are born from young mothers, suggesting that other risk factors than advanced maternal age must be involved. In this context, some studies demonstrated a possible link between DS and maternal polymorphisms in genes involved in folate metabolism. These polymorphisms, as well as low intake of folate could generate genomic instability, DNA hypomethylation and abnormal segregation, leading to trisomy 21. We compared the frequency of CBS 844ins68, MTR 2756A>G, RFC-1 80G> A and TC 776C>G polymorphisms among 114 case mothers and 110 matched controls, in order to observe whether these variants act as risk factors for DS. The genotype distributions revealed that there were not significant differences between both samples. However, when we proceed the multiplicative interaction analyses between the four polymorphisms described above together with the previously studied MTHFR 677C>T, MTHFR 1298A>C and MTRR 66A>G polymorphisms, our results show that the combined genotype TC 776CC / MTHFR 677TT and TC 776CC / MTR 2756AG were significantly higher in the control sample. Nevertheless, there was no significant association after Bonferroni correction. Our results suggest that maternal folate-related polymorphisms studied here have no influence on trisomy 21 susceptibility in subjects of Brazilian population.

The impact of folate pathway polymorphisms combined to nutritional deficiency as a maternal predisposition factor for Down syndrome.

Polymorphisms in genes encoding folate metabolizing enzymes have been linked to an increased risk of maternal chromosomal nondisjunction in several populations. With the purpose of evaluating this relationship, we compared the frequencies of 677C>T and 1298A>C polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR) and 66A>G in the methionine synthase reductase gene (MTRR) between 103 young mothers of Down syndrome (DS) individuals and 108 control mothers, whose offspring was karyotypically normal, correlating it with an estimative of folate and - related micronutrients levels intake. Maternal and paternal transmission frequencies of MTHFR 677T allele were also examined to access potential parent-of-origin effects. PCR-RFLP for genomic DNA was accomplished and allele/genotype frequencies differences were determined using the x(2) test, whereas pattern of transmission of the MTHFR 677 allele was analyzed by transmission disequilibrium test. None of the polymorphisms seemed to be more frequent in case mothers than in controls, either individually or combined. The estimative of nutritional intake revealed that folate consumption median was inadequate in both groups, whereas methionine and zinc consumption medians were significantly greater in control mothers. It suggests that such interaction between genetic profile and environment could predispose this sub group of women to have a DS child. Additional studies focusing the interaction between nutritional intakes, biochemical data and folate pathway polymorphisms are needed to confirm the present results. The possibility of neutralize the biochemical negative effects of folate-related polymorphisms through oral supplementation could provide new targets for DS prevention.

Implication of abnormal epigenetic patterns for human diseases.

Significant evidences have brought new insights on the mechanisms by which epigenetic machinery proteins regulate gene expression, leading to a redefinition of chromatin regulation in terms of modification of core histones, DNA methylation, RNA-mediated silencing pathways, action of methylation-dependent sensitive insulators and Polycomb/Trithorax group proteins. Consistent with these fundamental aspects, an increasing number of human pathologies have been found to be associated with aberrant epigenetics regulation, including cancer, mental retardation, neurodegenerative symptoms, imprinting disorders, syndromes involving chromosomal instabilities and a great number of human life-threatening diseases. The possibility of reversing epigenetic marks, in contrast to genetic code, may provide new pharmacological targets for emerging therapeutic intervention.

LEPR p.Q223R, beta3-AR p.W64R and LEP c.-2548G>A gene variants in obese Brazilian subjects.

Obesity is due to the combined effects of genes, environment, lifestyle, and the interactions of these factors. The adrenergic receptor beta3 (beta3-AR), leptin (LEP) and leptin receptor (LEPR) genes have been intensively evaluated in the search of variants that could be related to obesity and its cardiometabolic complications. The results of most of these studies have been controversial. In the present study, we investigated the relationship of the beta3-AR p.W64R, LEP c.-2548G>A and LEPR p.Q223R gene variants with body mass index (BMI), in Brazilian subjects of different genetic backgrounds and ethnic origins. Two hundred obese patients (60 males, 140 females, BMI > or = 30 kg/m2) were screened and compared to 150 lean healthy subjects (63 males, 87 females, BMI < or = 24 kg/m2). Genomic DNA was extracted and amplified by polymerase chain reaction. Polymerase chain reaction products were digested with specific restriction enzymes and separated by electrophoresis. There was no significant difference in the genotype frequency of the beta3-AR p.W64R and the LEP c.-2548G>A polymorphisms, between lean and obese subjects. However, the genotype and allele frequencies of the LEPR p.Q223R variant were significantly different between the normal weight and obese groups. Haplotype analysis has shown an association between the G/G allelic combination of c.-2548G>A LEP and c.668A>G LEPR, in obese subjects. Our results suggest that genetic variability in the leptin receptor is associated with body weight regulation, the LEPR p.Q223R variant being related to BMI increase. The haplotype combination of LEP c.-2548G>A and LEPR p.Q223R variants was related to a 58% increase in obesity risk.

LEPR p. Q223R, Beta 3-AR p. W64R and LEPc. -2548G>A gene variants in obese Brazilian subjects

Obesity is due to the combined effects of genes, environment, lifestyle, and the interactions of these factors. The adrenergic receptor ¦Â3 (¦Â3-AR), leptin (LEP) and leptin receptor (LEPR) genes have been intensively evaluated in the search of variants that could be related to obesity and its cardiometabolic complications. The results of most of these studies have been controversial. In the present study, we investigated the relationship of the ¦Â3-AR p.W64R, LEP c.-2548G>A and LEPR p.Q223R gene variants with body mass index (BMI), in Brazilian subjects of different genetic backgrounds and ethnic origins. Two hundred obese patients (60 males, 140 females, BMI ¡Ý 30 kg/m2) were screened and compared to 150 lean healthy subjects (63 males, 87 females, BMI ¡Ü 24 kg/m2). Genomic DNA was extracted and amplified by polymerase chain reaction. Polymerase chain reaction products were digested with specific restriction enzymes and separated by electrophoresis. There was no significant difference in the genotype frequency of the ¦Â3-AR p.W64R and the LEP c.-2548G>A polymorphisms, between lean and obese subjects. However, the genotype and allele frequencies of the LEPR p.Q223R variant were significantly different between the normal weight and obese groups. Haplotype analysis has shown an association between the G/G allelic combination of c.-2548G>A LEP and c.668A>G LEPR, in obese subjects. Our results suggest that genetic variability in the leptin receptor is associated with body weight regulation, the LEPR p.Q223R variant being related to BMI increase. The haplotype combination of LEP c.-2548G>A and LEPR p.Q223R variants was related to a 58% increase in obesity risk.

Premature ovarian failure and FMR1 premutation co-segregation in a large Brazilian family.

Fragile X syndrome is the most common form of inherited mental retardation in men. The molecular mechanism underlying the disease is an amplification of a polymorphic trinucleotide repeat (CGG)n located at 5' end of FMR1 which promotes transcriptional silencing of the gene. Four different classes of alleles could be distinguished in the population based on the size of the repeat, however only large amplifications over 200 CGG are associated with the disease. In the past decade several authors have associated premutated alleles, which harbor expansions from 61 to 200 repeats, with the occurrence of premature ovarian failure (POF). In this work we describe a large Brazilian family in which a POF/premutated woman has transmitted to five out of seven daughters a FMR1 premutated allele. From these five women with premutations, three have experienced premature ovarian failure. Our data clearly indicate a co-segregation pattern of inheritance between POF and fragile X premutation.

Chromosomal investigations in patients with mental retardation and/or congenital malformations

Neste estudo investigamos a organizaçäo cromossômica de pacientes com retardo mental e/ou malformaçöes congênitas, visando a avaliaçäo de causas genéticas associadas a estes distúrbios. Os padröes de bandas GTG e CBG foram estudados a partir da cultura de linfócitos de sangue periférico, estimulados por fitohemaglutinina M. Dentre os 98 indivíduos portadores de retardo mental e/ou malformaçöes congênitas analisados, diagnosticamos as seguintes síndromes: 12 casos de Down, dois de Edwards, um de Patau, cinco de Turner, dois de Klinefelter, um de "cri-du-chat", e um caso de translocaçäo balanceada entre os cromossomos 13 e 14, um caso de cromossomo derivado e um outro de cromossomo marcador. Encontramos anomalias cromossômicas em 26 por cento dos pacientes, das quais 82 por cento eram alteraçöes numéricas e o restante (18 por cento) representou rearranjos estruturais. Este percentual significativo enfatiza o uso da cariotipagem de rotina em pacientes com retardo mental e/ou malformaçöes congênitas.

Estudos cromossômicos em indivíduos portadores de retardo mental e atraso psicomotor / Chromosomal investigation in mentally handicapped and psychomotor retardation patients

O retardo mental é uma característica comum aos pacientes que buscam o Serviço de Genética Médica, apresentando heterogeneidade clínica e etiológica. Neste trabalho, estudos cromossômicos foram realizados em 30 indivíduos portadores de retardo mental e atraso psicomotor. Verificamos que 40 por cento dos indivíduos investigados apresentaram anomalias cromossômicas. Nos demais casos (60 por cento) o cariótipo foi normal. Este estudo reforça a importância da investigaçåo citogenética em indivíduos portadores de retardo mental e atraso psicomotor rastreando aberraçöes cromosssômicas numéricas ou estruturais e auxiliando no diagnóstico, prognóstico e aconselhamento gewnético das famílias

Estudos cromossomicos em individuos portadores de retardo mental e atraso psicomotor

O retardo mental e uma caracteristica comum aos pacientes que buscam o Servico de Genetica Medica, apresentando heterogeneidade clinica e etiologica. Neste trabalho, estudos cromossomicos foram realizados em 30 individuos portadores de retardo mental e atraso psicomotor: Verificamos que 40 por cento dos individuos investigados apresentaram anomalias cromossomicas. Nos demais casos (60 por cento) o cariotipo foi normal. Este estudo reforca a importancia da investigacao citogenetica em individuos portadores de retardo mental e atraso psicomotor rastreando aberracoes cromossomicas numericas ou estruturais e auxiliando no diagnostico e Aconselhamento Genetico das familias.