João Neto

COL1A1 and miR-29b show lower expression levels during osteoblast differentiation of bone marrow stromal cells from Osteogenesis Imperfecta patients

BackgroundThe majority of Osteogenesis Imperfecta (OI) cases are caused by mutations in one of the two genes, COL1A1 and COL1A2 encoding for the two chains that trimerize to form the procollagen 1 molecule. However, alterations in gene expression and microRNAs (miRNAs) are responsible for the regulation of cell fate determination and may be evolved in OI phenotype.MethodsIn this work, we analyzed the coding region and intron/exon boundaries of COL1A1 and COL1A2 genes by sequence analysis using an ABI PRISM 3130 automated sequencer and Big Dye Terminator Sequencing protocol. COL1A1 and miR-29b expression were also evaluated during the osteoblastic differentiation of mesenchymal stem cell (MSC) by qRT-PCR using an ABI7500 Sequence Detection System.ResultsWe have identified eight novel mutations, where of four may be responsible for OI phenotype. COL1A1 and miR-29b showed lower expression values in OI type I and type III samples. Interestingly, one type III OI sample from a patient with Bruck Syndrome showed COL1A1 and miR-29b expressions alike those from normal samples.ConclusionsResults suggest that the miR-29b mechanism directed to regulate collagen protein accumulation during mineralization is dependent upon the amount of COL1A1 mRNA. Taken together, results indicate that the lower levels observed in OI samples were not sufficient for the induction of miR-29b.

Fenótipo comportamental de crianças e adolescentes com síndrome de Prader-Willi

Objective: To identify the main characteristics of the behavioral phenotype of children and adolescents with Prader-Willi syndrome. Methods: Eleven children and adolescents with clinical and cytogenetic-molecular diagnosis of Prader-Willi syn- drome were studied. Data collection was obtained by the Child Behavior Checklist for Ages 6-18 (CBCL/6-18). Bi- variate correlations were used to test the association between the analyzed variables, being significant p<0.05. Results: The behavioral profile obtained was consid - ered as clinical in different scales of the CBCL/6-18 tool. A behavioral pattern with high frequency of aggression, rule breaking and opposition was observed. Statistically significant correlations between attention and social prob - lems and between thought problems and breaking rules were identified.

GM1 gangliosidosis: Clinical and laboratory findings in eight families

SummaryGM1 Gangliosidosis is an autosomal recessive genetic disorder due to deficiency of the lysosome enzyme beta-galactosidase, with consequent tissue accumulation of glycolipids, oligosaccharides, and especially GM1 ganglioside. In the present paper we report the clinical and laboratory findings obtained for eight families starting from eight index cases exhibiting the childhood form of the disease. The total number of cases in these families may be as high as 14, thus causing GM1 gangliosidosis to be the inborn metabolic error most frequently diagnosed in our service.Hypotonia, neuromotor retardation, hepatosplenomegaly, macrocephaly, and hydrocele are some of the most frequent clinical findings. The disease evolves towards convulsions and bronchopneumonia, leading to patient death generally during the first half of the second year of life. The presence of vacuolated lymphocytes, alterations of the lumbar vertebrae, and cherry spots on the retina were observed in almost all patients. When tested for inborn metabolic errors, all patients gave normal results, a fact that may have confused and delayed diagnosis. Diagnosis was made by urine oligosaccharide chromatography and confirmed by beta-galactoside measurement in peripheral blood leukocytes. This method proved to be accurate also for the detection of heterozygotes, which permitted post-mortem diagnosis in two families.The authors speculate that increased fetal loss and tendency towards macrosomy may be possible characteristics of the disease, suggest that testing for vacuolated lymphocytes be used as a screening method, and propose that urine oligosaccharide chromatography be included in the routine screening for inborn metabolic errors.

A further case of a Prader-Willi syndrome phenotype in a patient with Angelman syndrome molecular defect

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are distinct human neurogenetic disorders; however, a clinical overlap between AS and PWS has been identified. We report on a further case of a patient showing the PWS phenotype with the AS molecular defect. Despite the PWS phenotype, the DNA methylation analysis of SNRPN revealed an AS pattern. Cytogenetic and FISH analysis showed normal chromosomes 15 and microsatellite analysis showed heterozygous loci inside and outside the 15q11-13 region. The presence of these atypical cases could be more frequent than previously expected and we reinforce that the DNA methylation analysis is important for the correct diagnosis of severe mental deficiency, congenital hypotonia and obesity.

Recurrent meningitis in a case of congenital anterior sacral meningocele and agenesis of sacral and coccygeal vertebrae

A rare case of recurrent meningitis due to congenital anterior sacral meningocele and agenesis of the sacral and coccygeal vertebrae is described. An autosomal dominant inheritance is demonstrated for lower cord malformation, and environmental factors (chromic acid or fumes) are discussed.

Leigh-like syndrome with the T8993G mutation in the mitochondrial ATPase 6 gene: long-term follow-up discloses a slowly progressive course

We describe the long-term clinical outcome of a patient with Leigh-like syndrome presenting as an early onset encephalopathy and peripheral neuropathy caused by the T8993G mutation in the mitochondrial DNA (mtDNA). Clinical follow-up for 20 years revealed a peculiar pattern of slow disease progression, characterized by the addition of new minor deficits, while worsening of previous symptoms was mild. Brain MRI revealed cerebellar atrophy, diffuse demyelination of corona radiata and parietal white matter, and bilateral and symmetrical putaminal lesions. The proportion of mutant mtDNAs in blood was 72% (+/-0.02%) and in skeletal muscle was 81% (+/-0.4%). Leigh-like syndrome caused by the T8993G mtDNA mutation is a progressive disease, although not necessarily associated with an aggressive clinical course.

Gene expression profiling of bone marrow mesenchymal stem cells from Osteogenesis Imperfecta patients during osteoblast differentiation

Mesenchymal stem cells (MSCs) are precursors present in adult bone marrow that are able to differentiate into osteoblasts, adipocytes and chondroblasts that have gained great importance as a source for cell therapy. Recently, a number of studies involving the analysis of gene expression of undifferentiated MSCs and of MSCs in the differentiation into multiple lineage processes were observed but there is no information concerning the gene expression of MSCs from Osteogenesis Imperfecta (OI) patients. Osteogenesis Imperfecta is characterized as a genetic disorder in which a generalized osteopenia leads to excessive bone fragility and severe bone deformities. The aim of this study was to analyze gene expression profile during osteogenic differentiation from BMMSCs (Bone Marrow Mesenchymal Stem Cells) obtained from patients with Osteogenesis Imperfecta and from control subjects. Bone marrow samples were collected from three normal subjects and five patients with OI. Mononuclear cells were isolated for obtaining mesenchymal cells that had been expanded until osteogenic differentiation was induced. RNA was harvested at seven time points during the osteogenic differentiation period (D0, D+1, D+2, D+7, D+12, D+17 and D+21). Gene expression analysis was performed by the microarray technique and identified several differentially expressed genes. Some important genes for osteoblast differentiation had lower expression in OI patients, suggesting a smaller commitment of these patients MSCs with the osteogenic lineage. Other genes also had their differential expression confirmed by RT-qPCR. An increase in the expression of genes related to adipocytes was observed, suggesting an increase of adipogenic differentiation at the expense osteogenic differentiation.

Osteoblastic differentiation of bone marrow mesenchymal stromal cells in Bruck Syndrome

BackgroundOsteogenesis Imperfecta (OI) (OMIM %259450) is a heterogeneous group of inherited disorders characterized by increased bone fragility, with clinical severity ranging from mild to lethal. The majority of OI cases are caused by mutations in COL1A1 or COL1A2. Bruck Syndrome (BS) is a further recessively-inherited OI-like phenotype in which bone fragility is associated with the unusual finding of pterygia and contractures of the large joints. Notably, several studies have failed to show any abnormalities in the biosynthesis of collagen 1 in BS patientes. Evidence was obtained for a specific defect of the procollagen telopeptide lysine hydroxylation in BS, whereas mutations in the gene PLOD2 have been identified. Recently, several studies described FKBP10 mutations in OI-like and BS patients, suggesting that FKBP10 is a bonafide BS locus.MethodsWe analyzed the coding region and intron/exon boundaries of COL1A1, COL1A2, PLOD2 and FKBP10 genes by sequence analysis using an ABI PRISM 3130 automated sequencer and Big Dye Terminator Sequencing protocol. Mononuclear cells obtained from the bone marrow of BS, OI patients and healthy donors were cultured and osteogenic differentiation was induced. The gene expression of osteoblast specific markers were also evaluated during the osteoblastic differentiation of mesenchymal stem cell (MSC) by qRT-PCR using an ABI7500 Sequence Detection System.ResultsNo mutations in COL1A1, COL1A2 or PLOD2 were found in BS patient. We found a homozygous 1-base-pair duplication (c.831dupC) that is predicted to produce a translational frameshift mutation and a premature protein truncation 17 aminoacids downstream (p.Gly278ArgfsX95). The gene expression of osteoblast specific markers BGLAP, COL1A1, MSX2, SPARC and VDR was evaluated by Real Time RT-PCR during differentiation into osteoblasts and results showed similar patterns of osteoblast markers expression in BS and healthy controls. On the other hand, when compared with OI patients, the expression pattern of these genes was found to be different.ConclusionsOur work suggests that the gene expression profiles observed during mesenchymal stromal cell differentiation into osteoblast are distinct in BS patients as compared to OI patients. The present study shows for the first time that genes involved in osteogenesis are differentially expressed in BS and OI patients.