Molecular basis of various forms of maple syrup urine disease in Chilean patients.

BACKGROUND: Maple syrup urine disease (MSUD) is an autosomal recessive inherited metabolic disorder caused by the deficient activity of the branched-chain α-keto acid dehydrogenase (BCKD) enzymatic complex. BCKD is a mitochondrial complex encoded by four genes: BCKDHA, BCKDHB, DBT, and DLD. MSUD is predominantly caused by mutations in the BCKDHA, BCKDHB, and DBT genes which encode the E1α, E1ß, and E2 subunits of the BCKD complex, respectively. The aim of this study was to characterize the genetic basis of MSUD in a cohort of Chilean MSUD patients by identifying point mutations in the BCKDHA, BCKDHB, and DBT genes and to describe their impact on the phenotypic heterogeneity of these patients. METHODS: This manuscript describes a cross-sectional study of 18 MSUD patients carried out using PCR and DNA sequencing. RESULTS: Four novel pathogenic mutations were identified: one in BCKDHA (p.Thr338Ile), two in BCKDHB (p.Gly336Ser e p.Pro240Thr), and one in DBT (p.Gly406Asp). Four additional pathogenic mutations found in this study have been described previously. There were no correlations between the genotype and phenotype of the patients. CONCLUSION: If MSUD is diagnosed earlier, with a newborn screening approach, it might be possible to establish genotype-phenotype relationships more efficiently.

Non-Syndromic Intellectual Disability and Its Pathways: A Long Noncoding RNA Perspective.

Non-syndromic intellectual disability (NS-ID or idiopathic) is a complex neurodevelopmental disorder that represents a global health issue. Although many efforts have been made to characterize it and distinguish it from syndromic intellectual disability (S-ID), the highly heterogeneous aspect of this disorder makes it difficult to understand its etiology. Long noncoding RNAs (lncRNAs) comprise a large group of transcripts that can act through various mechanisms and be involved in important neurodevelopmental processes. In this sense, comprehending the roles they play in this intricate context is a valuable way of getting new insights about how NS-ID can arise and develop. In this review, we attempt to bring together knowledge available in the literature about lncRNAs involved with molecular and cellular pathways already described in intellectual disability and neural function, to better understand their relevance in NS-ID and the regulatory complexity of this disorder.

A non-functional galanin receptor-2 in a multiple sclerosis patient.

Multiple Sclerosis (MS) is an inflammatory neurodegenerative disease that affects approximately 2.5 million people globally. Even though the etiology of MS remains unknown, it is accepted that it involves a combination of genetic alterations and environmental factors. Here, after performing whole exome sequencing, we found a MS patient harboring a rare and homozygous single nucleotide variant (SNV; rs61745847) of the G-protein coupled receptor (GPCR) galanin-receptor 2 (GALR2) that alters an important amino acid in the TM6 molecular toggle switch region (W249L). Nuclear magnetic resonance imaging showed that the hypothalamus (an area rich in GALR2) of this patient exhibited an important volumetric reduction leading to an enlarged third ventricle. Ex vivo experiments with patient-derived blood cells (AKT phosphorylation), as well as studies in recombinant cell lines expressing the human GALR2 (calcium mobilization and NFAT mediated gene transcription), showed that galanin (GAL) was unable to stimulate cell signaling in cells expressing the variant GALR2 allele. Live cell confocal microscopy showed that the GALR2 mutant receptor was primarily localized to intracellular endosomes. We conclude that the W249L SNV is likely to abrogate GAL-mediated signaling through GALR2 due to the spontaneous internalization of this receptor in this patient. Although this homozygous SNV was rare in our MS cohort (1:262 cases), our findings raise the potential importance of impaired neuroregenerative pathways in the pathogenesis of MS, warrant future studies into the relevance of the GAL/GALR2 axis in MS and further suggest the activation of GALR2 as a potential therapeutic route for this disease.

Lacrimal Gland Involvement in Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome.

PURPOSE: To describe the involvement of the lacrimal gland (LG) in blepharophimosis-ptosis-epicanthus inversus syndrome (BPES). DESIGN: Observational, cross-sectional study. PARTICIPANTS: Twenty-one patients with BPES (10 female, 11 male) aged on average 15 years (range, 2-39 years), from 3 Brazilian medical centers and 1 Portuguese medical center. METHODS: Patients had their ocular surface evaluated with slit-lamp biomicroscopy, and tear production quantified with the Schirmer test I. The LG volumes were measured on computed tomography (CT) scans in the BPES sample and in a group of age-matched subjects imaged for nonorbital diseases. Sixteen patients were screened for mutations in the FOXL2 gene. MAIN OUTCOME MEASURES: Lacrimal meniscus height, Schirmer test I, presence of superficial punctate keratopathy (SPK), LG volume, and molecular analysis of the FOXL2 gene. RESULTS: Absence of LG was detected bilaterally in 9 patients (42.8%) and unilaterally in 2 patients (9.5%). When considering only patients with measurable LG, the median volume was 0.22 cm3 in the right eye (range, 0.06-0.36 cm3) and 0.24 cm3 in the left eye (range, 0.08-0.34 cm3). These values were significantly lower than those for the age-matched controls (median = 0.54 right eye and 0.53 left eye; P < 0.05). There was a significant association between deficiency of tear production and LG volume reduction and agenesis. Molecular analysis of the FOXL2 gene revealed the presence of 8 distinct mutations, 4 of them novel ones. A significant reduction of LG size or agenesis was associated with mutations affecting protein size (due to underlying changes in the stop codon location) or the DNA-binding forkhead domain (Fisher exact test, P = 0.021). In 3 probands, the underlying genetic defect was not found. CONCLUSIONS: This is the first study reporting LG volumes in BPES, describing a significant number of patients with LG agenesis. The association between alacrima and BPES is not incidental, and a thorough evaluation of tear production is recommended especially if ptosis surgery is planned.

Clinical profile and molecular characterization of Galactosemia in Brazil: identification of seven novel mutations.

BACKGROUND: Classical Galactosemia (CG) is an inborn error of galactose metabolism caused by the deficiency of the galactose-1-phosphate uridyltransferase enzyme. It is transmitted as an autosomal recessive disease and is typically characterized by neonatal galactose intolerance, with complications ranging from neonatal jaundice and liver failure to late complications, such as motor and reproductive dysfunctions. Galactosemia is also heterogeneous from a molecular standpoint, with hundreds of different mutations described in the GALT gene, some of them specific to certain populations, reflecting consequence of founder effect. METHODS: This study reviews the main clinical findings and depicts the spectrum of mutations identified in 19 patients with CG, six with Duarte Galactosemia and one with type 2 Galactosemia in Brazil. Some individuals were diagnosed through expanded newborn screening test, which is not available routinely to all newborns. RESULTS: The main classical Galactosemia mutations reported to date were identified in this study, as well as the Duarte variant and seven novel mutations - c.2 T > C (p.M1T), c.97C > A (p.R33S), c.217C > T (p.P73S), c.328 + 1G > A (IVS3 + 1G > A), c.377 + 4A > C (IVS4 + 4A > C), c.287_289delACA (p.N97del) and c.506A > C (p.Q169P). This was expected, given the high miscegenation of the Brazilian population. CONCLUSIONS: This study expands the mutation spectrum in GALT gene and reinforces the importance of early diagnosis and introduction of dietary treatment, what is possible with the introduction of Galactosemia in neonatal screening programs.

Mitochondrial genome instability in colorectal adenoma and adenocarcinoma.

Mitochondrial dysfunction is regarded as a hallmark of cancer progression. In the current study, we evaluated mitochondrial genome instability and copy number in colorectal cancer using Next Generation Sequencing approach and qPCR, respectively. The results revealed higher levels of heteroplasmy and depletion of the relative mtDNA copy number in colorectal adenocarcinoma. Adenocarcinoma samples also presented an increased number of mutations in nuclear genes encoding proteins which functions are related with mitochondria fusion, fission and localization. Moreover, we found a set of mitochondrial and nuclear genes, which cooperate in the same mitochondrial function simultaneously mutated in adenocarcinoma. In summary, these results support an important role for mitochondrial function and genomic instability in colorectal tumorigenesis.

Biochemical and genetic analysis of butyrylcholinesterase (BChE) in a family, due to prolonged neuromuscular blockade after the use of succinylcholine.

Butyrylcholinesterase (BChE) is a plasma enzyme that catalyzes the hydrolysis of choline esters, including the muscle-relaxant succinylcholine and mivacurium. Patients who present sustained neuromuscular blockade after using succinylcholine usually carry BChE variants with reduced enzyme activity or an acquired BChE deficiency. We report here the molecular basis of the BCHE gene underlying the slow catabolism of succinylcholine in a patient who underwent endoscopic nasal surgery. We measured the enzyme activity of BChE and extracted genomic DNA in order to study the promoter region and all exons of the BCHE gene of the patient, her parents and siblings. PCR products were sequenced and compared with reference sequences from GenBank. We detected that the patient and one of her brothers have two homozygous mutations: nt1615 GCA > ACA (Ala539Thr), responsible for the K variant, and nt209 GAT > GGT (Asp70Gly), which produces the atypical variant A. Her parents and two of her brothers were found to be heterozygous for the AK allele, and another brother is homozygous for the normal allele. Sequence analysis of exon 1 including 5'UTR showed that the proband and her brother are homozygous for -116GG. The AK/AK genotype is considered the most frequent in hereditary hypocholinesterasemia (44%). This work demonstrates the importance of defining the phenotype and genotype of the BCHE gene in patients who are subjected to neuromuscular block by succinylcholine, because of the risk of prolonged neuromuscular paralysis.

Biochemical and genetic analysis of butyrylcholinesterase (BChE) in a family, due to prolonged neuromuscular blockade after the use of succinylcholine

Butyrylcholinesterase (BChE) is a plasma enzyme that catalyzes the hydrolysis of choline esters, including the muscle-relaxant succinylcholine and mivacurium. Patients who present sustained neuromuscular blockade after using succinylcholine usually carry BChE variants with reduced enzyme activity or an acquired BChE deficiency. We report here the molecular basis of the BCHE gene underlying the slow catabolism of succinylcholine in a patient who underwent endoscopic nasal surgery. We measured the enzyme activity of BChE and extracted genomic DNA in order to study the promoter region and all exons of the BCHE gene of the patient, her parents and siblings. PCR products were sequenced and compared with reference sequences from GenBank. We detected that the patient and one of her brothers have two homozygous mutations: nt1615 GCA > ACA (Ala539Thr), responsible for the K variant, and nt209 GAT > GGT (Asp70Gly), which produces the atypical variant A. Her parents and two of her brothers were found to be heterozygous for the AK allele, and another brother is homozygous for the normal allele. Sequence analysis of exon 1 including 5'UTR showed that the proband and her brother are homozygous for -116GG. The AK/AK genotype is considered the most frequent in hereditary hypocholinesterasemia (44 percent). This work demonstrates the importance of defining the phenotype and genotype of the BCHE gene in patients who are subjected to neuromuscular block by succinylcholine, because of the risk of prolonged neuromuscular paralysis.

ProbFAST: Probabilistic functional analysis system tool.

BACKGROUND: The post-genomic era has brought new challenges regarding the understanding of the organization and function of the human genome. Many of these challenges are centered on the meaning of differential gene regulation under distinct biological conditions and can be performed by analyzing the Multiple Differential Expression (MDE) of genes associated with normal and abnormal biological processes. Currently MDE analyses are limited to usual methods of differential expression initially designed for paired analysis. RESULTS: We proposed a web platform named ProbFAST for MDE analysis which uses Bayesian inference to identify key genes that are intuitively prioritized by means of probabilities. A simulated study revealed that our method gives a better performance when compared to other approaches and when applied to public expression data, we demonstrated its flexibility to obtain relevant genes biologically associated with normal and abnormal biological processes. CONCLUSIONS: ProbFAST is a free accessible web-based application that enables MDE analysis on a global scale. It offers an efficient methodological approach for MDE analysis of a set of genes that are turned on and off related to functional information during the evolution of a tumor or tissue differentiation. ProbFAST server can be accessed at http://gdm.fmrp.usp.br/probfast.

Estudo genético-clínico e citogenético de crianças autistas / Clinical, genetic and cytogenetic study of autistic children

O autismo infantil é caracterizado pelo comportamento típico que pode ser causado por uma doença orgânica ou por um distúrbio emocional. Através de um estudo genético-clínico e citogenético, tivemos como objetivo detectar a presença de doenças orgânicas, principalmente de etiologia genética, que pudessem estar relacionadas com o quadro de autismo, apresentado por dezessete meninos que freqüentavam a AMA de Ribeiräo Preto. Concluímos que quatorze indivíduos nao possuíam alteraçöes orgânicas que pudessem estar relacionadas com o quadro clínico por eles apresentado; um indivíduo apresentou quadro clínico compatível com macrocefalia; um indivíduo apresentou quadro clínico compatível com uma nova síndrome de deficiência mental, ligada ao X, associada a macrossomia, macrocefalia e obesidade, e um indivíduo apresentou a Síndrome de Angelman (SA). O estudo citogenético mostrou-se normal para todos os indivíduos estudados, assim como a pesquisa de fragilidade Xq27.3, excluindo a todos da possibilidade de apresentarem a Síndrome do X-frágil. O estudo molecular, específico para a detecçäo da SA, revelou a presença, no paciente, de herança biparenteral para os marcadores utilizados; como a clínica desse paciente e extremamente sugestiva, concluímos estar frente a um caso de SA com herança biparenteral.