Browsing by Author "Candeias, Cristina"
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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.
- A de novo complex chromosome rearrangement (CCR) involving chromosome 5, 6 and 15Publication . Candeias, Cristina; Mota Freitas, Manuela; Magalhães, Sara; Rocha, Miguel; Marques, Bárbara; Correia, Hildeberto; Oliva Teles, Natália; Fonseca da Silva, Maria da Luz
- A "de novo" inv dup del(6q) - a case reportPublication . Mota Freitas, Manuela; Candeias, Cristina; Oliva Teles, Natália; Soares, Gabriela; Tkachenko, Nataliya; Marques, Bárbara; Correia, Hildeberto; Fonseca da Silva, Maria da Luz
- 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.