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Browsing by Author "Gaspar, I"

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  • Germline MUTYH (MYH) mutations in Portuguese individuals with multiple colorectal adenomas
    Publication . Isidro, G; Laranjeira, F; Pires, A; Leite, J; Regateiro, FJ; Castro e Sousa, F; Soares, J; Castro, C; Giria, J; Brito, MJ; Medeira, A; Teixeira, R; Morna, H; Gaspar, I; Marinho, C; Jorge, R; Brehm, A; Ramos, JS; Boavida, MG
    Germinal mutations in the base excision repair (BER) gene MUTYH (MYH) have recently been described in association with predisposition to multiple colorectal adenomas and cancer. In contrast to the classic dominant condition of familial adenomatous polyposis (FAP) due to germinal mutations in the APC gene, the MYH polyposis is an autosomal recessive disease. The identification of individuals affected by MYH polyposis brings new and important implications for the diagnostic, screening, genetic counseling, follow up and therapeutic options in these patients. In this study, screening for germinal mutations in the MYH gene was performed in 53 Portuguese individuals with multiple colorectal adenomas or classic adenomatous polyposis, in whom no mutation had been identified in the APC gene. The results revealed the presence of biallelic germline MYH mutations in 21 patients. In addition, we here report 3 mutations (c.340T>C [p.Y114H]; c.503G>A [p.R168H]; and c.1186_1187insGG [p.E396fsX437]) which, to our knowledge, have not been previously described
    2004Journal article Open access Show more
  • Molecular diagnosis of Huntington disease in Portugal: implications for genetic counselling and clinical practice
    Publication . Costa, MC; Magalhães, P; Ferreirinha, F; Guimarães, L; Januário, C; Gaspar, I; Loureiro, L; Vale, J; Garrett, C; Regateiro, FJ; Magalhães, M; Sousa, A; Maciel, P; Sequeiros, J
    Huntington disease (HD) is a neurodegenerative, autosomal dominant disorder of late-onset, caused by the expansion of a CAG repeat in the coding region of the gene. Ours is the reference laboratory for genetic testing in HD, in Portugal, since 1998; 90.1% of all 158 families known were identified for the first time, including patients with unusual presentation or without family history. A total of 338 genetic tests were performed: 234 for diagnosis, 96 for presymptomatic and four for prenatal testing (four were done for family studies). Most referring physicians were neurologists (90.6%); 82.8% of all clinical diagnosis were confirmed, while 83.1% of those sent for exclusion were in fact excluded. In presymptomatic testing, an excess of female subjects (59.4%) was again verified; 37.5% of the consultands were found to be carriers. None of the foetuses, in four prenatal tests, were mutation carriers. One juvenile case was inherited from her mother. Our patient population is very similar to others described so far, namely in terms of mean age at onset and (CAG)(n) distribution, except perhaps for a higher frequency of large normal (class 2) alleles (3.7%). We also identify cases posing particular problems for genetic counselling, such as, 'homozygosity' that can pose a serious ethical dilemma, carriers of large normal alleles, and 'homoallelism' for a normal gene, which will demand further procedures and may delay results in presymptomatic and prenatal testing.
    2003Journal article Open access Show more