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  • Molecular characterization of the Portuguese patients with defects in GlcNAc-phosphotransferase: a key enzyme in the M6-P dependent lysosomal trafficking
    Publication . Coutinho, Maria Francisca; Encarnação, Marisa; Gomes, Rui; Prata, Maria João; Lacerda, Lúcia; Bargal, Ruth; Filocammo, Mirella; Raas-Rothschild; Tappino, Barbara; Laprise, Cathrine; Sirois-Gagnon, D.; Costa, Roberto; Ribeiro, Helena; Lopes, Lurdes; Alves, Sandra
    Introduction: GlcNAc-phosphotransferase is one of the enzymes responsible for the formation of M6P residues and plays a key role in lysosomal trafficking, since most soluble acid hydrolases reach these organelles through the M6P pathway. It is composed of six subunits (α2β2γ2), products of two genes recently cloned: GNPTAB (mutated in mucolipidosis II/IIIA patients) and GNPTG (mutated in MLIIIC patients). Methods: Using both gDNA and cDNA extracted from patient’s fibroblasts, we performed a molecular study of both genes in 13 MLII/III patients (10Portuguese, 1Finnish, 1Spanish of Arab origin and 1Indian). Expression studies were performed by quantitative real-time PCR. Results: We identified 11 different mutations, 8 of them novel: 6 in the GNPTAB gene (c.121delG;c.440delC;c.2249_50insA;W81L;I403T and E667) and 2 in the GNPTG gene (c.610-1G.T and c.639delT). Interestingly, although the MLII-causing mutations have been mostly found to be private or rare, there is one (c.3503_3504delTC) that shows a broad distribution having been detected among different populations. This same mutation was also the most frequent one in our patients. Such distribution pattern prompted us to perform a haplotypic study. We analysed 37 patients (23Italians, 8Arab Muslims, 1Turkish and 5Portuguese) for 3 intragenic polymorphisms and 2 microsatellite markers flanking the GNPTAB gene, identifying a common haplotype. Regarding the mRNA expression studies, real-time results suggest the existence of feedback regulation mechanisms between α/β and the γ subunits. Discussion/Conclusion: This work enabled the establishment of a strong genotype-phenotype correlation, which is of crucial importance to an improved genetic counselling for ML families. The sharing of an ancestral haplotype by patients carrying the deletion implies a common origin of this mutation, while the higher level of diversity observed at the most distant locus indicates that it is a relatively ancient one. The developed strategies constitute valuable tools that allow carrier detection and prenatal- molecular diagnostics of these diseases.
    2009-02-07Conference object Restricted access Show more
  • Serological and molecular survey of Anaplasma species infection in dogs with suspected tickborne disease in Portugal
    Publication . Santos, A.S.; Alexandre, N.; Sousa, R.; Núncio, M.S.; Bacellar, F.; Dumler, J.S.
    Fifty-five dogs with suspected tickborne disease were tested by immunofluorescence assay and PCR for Anaplasma phagocytophilum infection. Thirty (54·5 per cent) of the dogs were seropositive and five of them fulfilled the serological criteria for an active infection, with either seroconversion or a fourfold increase in antibody titres. Fragments of DNA of the expected size were detected by PCR in two seropositive and three seronegative dogs. However, direct amplicon sequencing failed to identify active A phagocytophilum infections, but revealed the presence of Anaplasma platys DNA in the PCR-positive animals.
    2009-02-07Journal article Restricted access Show more