Browsing by Author "Gaspar, Isabel"
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- A complex chromosomal rearrangement in a child with developmental delay, fractious behavior, and craniofacial anomalies, compatible with Smith-Magenis SyndromePublication . Simão, Laurentino; Alves, Cristina; Brito, Filomena; Marques, Bárbara; Ferreira, Cristina; Gaspar, Isabel; Dieudonne, V.; Cabral, P.; Meneses, I.; Duarte, Guida; Correia, HildebertoSmith-Magenis Syndrome (SMS) is a micro-deletion syndrome, and encompasses a picture of dysmorphology, mental defect, and fractious behavior. Evaluation of complex chromosome rearrangements (CCRs) and their potential phenotypic consequences is a common challenge in the genetics clinic and knowledge about the genotype/phenotype relationships are limited. We report the case of a 14-year-old boy who was referred by SMS, presenting developmental delay, fractious behavior, reduced sensitivity to pain, macrocranium and distinctive facial features. Following karyotyping, fluorescence in situ hybridization (FISH) using WCP probes for the chromosomes involved in CCR and 17p11.2 probe for SMS region was performed. Lately, chromosomal Comparative Genomic Hybridization (cCGH) and genomic microarray studies were also performed in order to identify genomic imbalances. The cytogenetic analysis revealed a karyotype: 46,XY,inv(3)(p23q27)t(3;10)(p13.2;p11.2),inv(14)(q13q32)dn.ish inv(3)t(3;10)(wcp10+), der(10)t(3;10)(wcp3+),inv(14)(wcp14+). Parental karyotypes were normal, although the father presented a marked cognitive delay. FISH analyses showed no deletion in 17p11.2 region and confirmed the cytogenetic results, namely the presence of CCR. Additionally, cCGH and genomic microarray studies did not reveal any gains/losses of genetic material in the breakpoints regions. Despite the clinical features of SMS, deletions or duplications in the SMS critical region were not detected in this patient. However, a small number of SMS present a mutation in the RAI1 gene instead of a 17p11.2 deletion, the former cause could not be excluded On the other hand, in CCRs de novo, an apparently balanced karyotype may be associated with an abnormal phenotype, including an increased risk of intellectual delay and congenital malformations. Further studies comprising, e.g., sequencing of the breakpoints, chromatin conformation analysis and refinement of the SMS critical region analysis might be useful to elucidate the phenotypic characteristics. However, the patient has been absent of routine clinical reevaluation; the etiology of the father’s cognitive delay could help shedding some light on the patient phenotypic features.
- Congenital adrenal hyperplasia in paediatric age: molecular analysis of the CYP21A2 gene and implications for genetic counsellingPublication . Gomes, Susana; Silva, Júlia; Pereira-Caetano, Iris; Lopes, Lurdes; Limbert, Catarina; Amaral, Daniela; Pina, Rosa; Kay, Teresa; Sampaio, Lurdes; Pereira, Carla; Moldovan, Oana; Berta, Ana; Rebelo, Irene; Gaspar, Isabel; Cidade Rodrigues, José; Lina, Ramos; Ramos, Fabiana; Dinis, Isabel; Cardoso, Rita; Mirante, Alice; Gonçalves, JoãoIntroduction: Congenital adrenal hyperplasia(CAH) is due to 21-hidroxilase deficiency(21-OHD) in about 95% of the cases. 21-OH is encoded by CYP21A2 gene, and most frequent mutations occurring in CYP21A2 are due to gene conversions originated from its pseudogene(CYP21A1P). The clinical severity of CAH is associated with the impairment of 21-OH activity, which is directly related with the molecular defect. CAH is classified as classic salt-wasting(SW) and simple virilising(SV) forms, and nonclassic(NC) form of the disease. SW and SV are usually diagnosed after birth or during the first years of life, respectively, while most cases of NC-CAH are diagnosed during infancy, puberty or until adult age. Here we present the molecular results performed in paediatric patients with CAH.
- Espectro de alterações moleculares detetadas no gene CYP21A2 associadas a deficiência em 21 hidroxilasePublication . Gomes, Susana; Pereira-Caetano, Iris; Lopes, Maria Lurdes; Limbert, Catarina; Amaral, Daniela; Pina, Rosa; Antunes, Diana; Carvalho, Inês; Kay, Teresa; Sampaio, Lurdes; Pereira, Carla; Moldovan, Oana; Berta, Ana; Rebelo, Irene; Gaspar, Isabel; Cardoso, Helena; Rodrigues, José Cidade; Ramos, Lina; Ramos, Fabiana; Dinis, Isabel; Cardoso, Rita; Mirante, Alice; Gonçalves, JoãoA maioria dos doentes com hiperplasia suprarrenal congénita (HSC) apresenta alterações moleculares no gene CYP21A2, o qual codifica a enzima 21-hidroxilase (21-OH). Os doentes com a forma clássica de deficiência em 21-OH (21-OHD) apresentam a síntese de cortisol diminuída no córtex adrenal e, os casos mais graves, também apresentam deficiência de aldosterona. As mulheres com 21-OHD grave apresentam excesso de andrógenos desde a sua vida fetal conduzindo à virilização dos órgãos genitais externos. Tanto homens como mulheres com 21-OHD completa não sintetizam a aldosterona e, consequentemente, logo após o nascimento, podem desenvolver crises de perda de sal se não forem corretamente diagnosticados e tratados. A 21- OHD não clássica é devida à deficiência parcial em 21-OH, os fenótipos clínicos são menos graves, as mulheres não apresentam virilização dos genitais externos ao nascimento, e geralmente os sinais relativos a excesso de androgénios podem surgir durante a infância ou até mais tarde (durante ou após a puberdade). Neste trabalho descrevem-se as alterações e os genótipos mais frequentes encontrados em doentes portugueses não adultos com 21-OHD. As alterações mais frequentes encontradas na forma clássica da HSC são c.293-13C> G, diferentes deleções/quimeras/conversões génicas do gene CYP21A2 e c.518T> A, enquanto na 21-OHD não-clássica a variante c.844G> T é a mais frequente. Estes resultados contribuem para um diagnóstico correto e uma melhor gestão clínica dos doentes, para o seu aconselhamento genético e para oferecer o diagnóstico pré-natal a casais com risco de ter filhos afetados com a forma clássica de 21-OHD.
- Next-Gen Cytogenetics and the Hidden Complexity of Genomic or Chromosomal RearrangementsPublication . David, Dezső; Freixo, João; Carvalho, Inês; Tkachenko, Natalia; Oliva Teles, Natália; Marques, Bárbara; Alves, Ana Cristina; Fortuna, Ana; Sofia, Dória; Pinto de Moura, Carla; Gaspar, Isabel; Marques Carreira, Isabel; Sá, Joaquim; Gonçalves, Rui; Lavinha, João; Kay, Teresa; Correia, Hildeberto; Talkowski, Michael E.; Morton, Cynthia C.Human developmental abnormalities are devastating conditions that account for almost half of all full-term neonatal deaths in developed countries. For individuals who survive, congenital anomalies often confer lifelong disability and their impact on public health is profound. However, the genetic etiology and genomic architecture contributing to the vast majority of these conditions remain unknown. Separately, and in addition, the genetic etiologies of recurrent infertility remain to be elucidated. The current low resolution diagnostic techniques are insensitive to the full mutational spectrum contributing to human developmental abnormalities and infertility, the poor understanding of the molecular alterations introduced by genomic rearrangements, and the lack of a fully annotated human genome hinders predictive diagnostics. This study results from collaboration between a Portuguese Consortium including clinical geneticists and the Developmental Genome Anatomy Project (DGAP) from Harvard Medical School. First, a group of cases were comparatively analyzed using genomic array and Next-Generation Sequencing (NGS). Subsequently, NGS of whole-genome large-insert libraries was applied for the identification of genomic or chromosomal rearrangements at nucleotide resolution in a series of cases, including two prenatal samples. Presently, this high-throughput technology is the only approach able to identify the full spectrum of structural variants, in a time frame that allows its application even for prenatal samples.The introduction of NGS into clinical cytogenetics surely will create a high-throughput, sequence-based Next-Gen Cytogenetics that will catalyze a dramatic advancement in clinical diagnostics. Therefore the understanding of the molecular pathology of these chromosome rearrangement-associated developmental disorders and infertilities will contribute to an improved prediction of the phenotypic consequences of these rearrangements.
- Small Deletion of 143 Kb Encompassing Exon 2 of the AUTS2: Rise of a NewMicrodeletion Syndrome?Publication . Serafim, Silvia; Marques, Barbara; Filomena, Brito; Pedro, Sónia; Ferreira, Cristina; Ventura, Catarina; Gaspar, Isabel; Correia, HildebertoChromosome microarray analysis is a powerful diagnostic tool and is being used as a first-line approach to detect chromosome imbalances associated with intellectual disability, dysmorphic features and congenital anomalies. This test enables the identification of new copy number variants (CNVs) and their association with new microdeletion/microduplication syndromes in patients previously without diagnosis. Here we report the case of a 17 year-old female with severe intellectual disability, absence of speech, microcephaly and congenital abnormalities with a previous normal karyotype performed at a younger age. Affymetrix CytoScan HD chromosome microarray analysis was performed detecting a 143 Kb deletion at the 7q11.22 breakpoint, encompassing exon 2 of AUTS2 gene: arr[hg19] 7q11.22(69238957- 69381975)×1. The AUTS2 gene has been recently implicated in neurodevelopment and is a candidate gene for numerous neurological disorders. Common clinical features described in patients with deletions in AUTS2 gene include intellectual disability, speech delay and microcephaly, among others. Thus, the CNV identified in our patient explains the phenotype observed. We compare our patient with other similar reported cases, adding additional value to the phenotypegenotype correlation of deletions in this region. The growing collection of new cases with similar phenotypes, and the observation of this deletion occurring frequently de novo, indicates this CNV as a possible new single gene microdeletion syndrome.