Percorrer por autor "Oliveira, Fernanda Paula"
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- Chromosome 1p36 deletion syndrome: a report on 4 casesPublication . Candeias, Cristina; Mota Freitas, Manuela; Ribeiro, Joana; Oliveira, Fernanda Paula; Aguiar, Joaquim; Oliva Teles, Natália; Soares, Gabriela; Carrilho, Inês; Martins, Márcia; Correia, Hildeberto; Fonseca Silva, Maria da LuzChromosome 1p36 deletion syndrome (MIM #607872) was first described in 1997 by Shapira et al. This condition is compatible with a monosomy of the 1p36 band in the distal region of the short arm of chromosome 1 and is the most common terminal deletion in humans, with an estimated prevalence of approximately 1 in 5,000 live births. This constitutional deletion is associated with mental retardation, developmental delay, seizures, hypotonia and heart defects. The syndrome is also characterized by several distinct dysmorphic features, including large anterior fontanels, microcephaly, brachycephaly, deep-set eyes, flat nose and nasal bridge, and pointed chin. The 1p36 band is not very clearly visible using classical cytogenetics, and it is therefore difficult to detect these deletions in banded karyotypes. Fluorescence in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA) analysis have increasingly been used, in addition to classical cytogenetic analysis, in children with mental retardation in order to identify this chromosomal abnormality. The authors present four patients between 1 month and 14 years of age with apparently normal karyotypes. Using molecular cytogenetic techniques, all cases showed a “pure” 1p36 deletion: three were detected by FISH (CEB108/T7, located at 1p36.3, Vysis) and are “de novo”; the fourth was detected by MLPA (P036 and P070, MRC Holland) analysis, and its origin is still unknown. The phenotypes of these patients are described and compared with other cases having this syndrome, described in the literature. We also emphasize the importance of good clinical characterization in order to establish the best cytogenetic strategy to assure accurate diagnosis.
- Detection of subtelomeric rearrangements in 1180 patients: FISH and MLPA contributionPublication . Mota Freitas, Manuela; Ribeiro, Joana; Candeias, Cristina; Lopes, Elisa; Oliveira, Fernanda Paula; Aguiar, Joaquim; Ribeiro, Maria Céu; Pires, Sílvia; Oliva Teles, Natália; Correia, Hildeberto; Fonseca Silva, Maria LuzMental retardation (MR) is a major social, educational, and health problem affecting 3% of the population. Subtelomeric chromosome aberrations are one of the major causes of MR with or without multiple anomalies; previous studies have shown that these rearrangements are responsible for 3-6% of unexplained mental retardation. Between 2000-2010 in the Cytogenetics Unit, Centro de Genética Médica Jacinto de Magalhães, INSA (Portugal), the subtelomeric regions of all the chromosomes were analysed in 1180 individuals, whose karyotype had been considered normal. The reasons for referral included (i) psychomotor development delay or (ii) mental retardation with or without dysmorphisms. Until 2007 the analysis of metaphases, obtained from cultured lymphocytes following standard protocols, were performed by "Fluorescence in situ hybridization” (FISH): the first kit to be used was the Chromoprobe Multiprobe-TM (Cytocell) kit (until 2005), which was followed by the TotelVysion Multi-Color FISH Probe (Vysis). In 2007 the "Multiplex Ligation dependent Probe Amplification” (MLPA) was implemented in the laboratory, using kits P036 and P070 (MRC-Holland). All the unbalanced cases detected by MLPA were confirmed by FISH. Of a total of 1180 individuals, 62 (5.3%) showed chromosomal alterations: 60 in the subtelomeric regions and 2 in the control regions. It was not possible to perform any familial studies in 12 of the 62 cases (1.0%) and therefore the results were considered inconclusive. In the other 50 abnormal cases, the parental investigation allowed us to conclude that 30 (2.5%) of these patients had chromosomal abnormalities “de novo” that might be responsible for the clinical phenotype; the remaining 20 possibly abnormal cases (1.7%) were considered polymorphisms without pathological significance, since the apparent deletion or duplication had been inherited from phenotypically normal parents. The authors compare the results obtained in the individuals in the present study with literature reports and highlight the advantages/disadvantages of each technique.
- Large interstitial del(13)(q13q14.3): the importance of detailed clinical information in cytogenetic studiesPublication . Oliveira, Fernanda Paula; Oliva Teles, Natália; Ribeiro, Joana; Mota Freitas, Manuela; Margarida, Azevedo; Correia, Hildeberto; Fonseca Silva, Maria da LuzInterstitial deletions of chromosome 13 are known to be associated with retinoblastoma. A wider syndrome may accompany the deletion, including mental retardation and craniofacial dysmorphism. The severity of the phenotype depends on the extent of the deletion. Retinoblastoma is a malignant tumor in the retina and is the most common ocular cancer in children. The association of most cases of retinoblastoma with an interstitial del(13q) has led to the localization of the retinoblastoma gene in 13q14. We report a case of a boy aged 8 referred for cytogenetic studies, presenting with mild mental retardation, craniofacial dysmorphism, delayed intrauterine growth (IUGR) and retinoblastoma. The karyotype was obtained from peripheral blood lymphocyte cultures using high-resolution GTG banding and standard techniques. Fluorescence in situ hybridization was performed using the LSI 13 (RB1) probe (Vysis) for region 13q14 spanning the RB1 gene. The chromosomal analysis revealed a large interstitial deletion of the long arm of chromosome 13. Although the exact breakpoints were difficult to establish, the deleted region did not appear to encompass the band which includes the retinoblastoma gene. Molecular cytogenetic techniques showed that the retinoblastoma gene was deleted. This confirmed the clinical indication of retinoblastoma and defined the deletion breakpoints more precisely. Final karyotype: 46,XY,del(13)(q13q14.3).ish del(13) (q14.1q14.3)(RB1−). Except for the presence of IUGR, the clinical description of this patient is in agreement with other reports in the literature. We would like to emphasize the importance of detailed clinical information that, together with classical and molecular cytogenetic techniques, could be useful in better defining the breakpoints, establishing correct genotype/phenotype correlation and thus providing appropriate genetic counselling. The blood samples of the parents were requested for karyotype analysis in order to clarify this chromosome deletion.