Browsing by Author "Amaral, O."
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- Adult-onset neuronopathic form of Gaucher's disease: a case reportPublication . Guimarães, J.; Amaral, O.; Sá Miranda, M.C.We report a patient with Gaucher's disease (GD) developing prominent neurological abnormalities in adult life confirming the existence of an adult neuronopathic form of GD. In this adult-onset form, an akinetic-rigid syndrome poorly responsive to dopatherapy, supranuclear gaze palsy, myoclonic jerks, seizures, cerebellar ataxia, cognitive and psychotic disturbances are frequent manifestations. The widely used clinical classification seems inadequate since it does not consider this rare form of GD. Until further understanding of the pathogenesis of the disease is achieved it is not possible to predict accurately which patients will or will not have late-onset nervous system involvement.
- Allelic frequency determination of the 24-bp chitotriosidase duplication in the Portuguese population by real-time PCRPublication . Rodrigues, M.R.; Sá Miranda, M.C.; Amaral, O.Chitotriosidase is a human chitinase produced by macrophages. Its enzymatic activity is markedly elevated in serum of patients suffering from lysosomal storage disorders, as well as other diseases in which macrophages are activated. Therefore, it is a useful tool as a secondary marker in the diagnosis of several disorders including Gaucher disease type 1 and Niemann–Pick disease. The determination of chitotriosidase levels as a diagnosis complement in some lysosomal storage disorders and in enzyme replacement therapy follow-up of Gaucher disease patients is of great importance. However, the fact that a mutation caused by a 24-bp duplication in the CHIT1 gene resulting in deficiency of plasma chitotriosidase activity is very frequent makes the establishment of the frequency of this mutation in different population groups necessary. Furthermore, in order to validate the use of chitotriosidase activity as a marker, it is indispensable to screen individuals for this particular mutation. In this work, we present the results of a study where the allelic frequency of the abovementioned CHIT1 gene mutation was determined in the Portuguese population by real-time PCR. The frequency of carriers encountered in this sample of Portuguese individuals was of 37%.
- Gaucher disease in Tunisia: High frequency of the most common mutationsPublication . Cherif, W.; Ben Turkia, H.; Ben Rhouma, F.; Riahi, I.; Chemli, J.; Kefi, R.; Messai, H.; Amaral, O.; Miranda, M.C.; Caillaud, C.; Tebib, N.; Ben Dridi, M.F.; Abdelhak, S.
- Gaucher disease: expression and characterization of mild and severe acid beta-glucosidase mutations in Portuguese type 1 patientsPublication . Amaral, O.; Marcão, A.; Sá Miranda, M.; Desnick, R.J.; Grace, M.E.Type 1 Gaucher disease (GD), the most prevalent lysosomal storage disease, results from the deficient activity of acid alpha-glucosidase. Molecular analysis of 12 unrelated Portuguese patients with type 1 GD identified three novel acid â-glucosidase mutations (F109V, W184R and R395P), as well as three previously reported, but uncharacterized, lesions (R359Q, G377S and N396T). The type 1 probands were either heteroallelic for the well-characterized common lesion, N370S, and the F109V, W184R, R359Q or N396T lesions or homoallelic for the G377S or N396T mutations. Expression of the W184R, R359Q, and R395P mutations revealed very low specific activities based on cross-reacting immunologic material (CRIM SAs of 0.0004, 0.016 and 0.045, respectively), consistent with their being found only in type 1 patients who had a neuroprotective N370S allele. In contrast, the F109V, G377S and N396T alleles had significant acid â-glucosidase activity (CRIM specific activities of 0.15, 0.17, 0.14, respectively), in agreement with their being mild type 1 alleles. Thus, these studies identified additional acid â-glucosidase mutations in the Portuguese population and demonstrated that the G377S and N396T mutations were neuroprotective, consistent with the mild clinical phenotypes of the type 1 patients who were homoallelic for the G377S and N396T lesions.
- Gaucher disease: the origins of the Ashkenazi Jewish N370S and 84GG acid beta-glucosidase mutationsPublication . Diaz, G.A.; Gelb, B.D.; Risch, N.; Nygaard, T.G.; Frisch, A.; Cohen, I.J.; Miranda, C.S.; Amaral, O.; Maire, I.; Poenaru, L.; Caillaud, C.; Weizberg, M.; Mistry, P.; Desnick, R.J.Type 1 Gaucher disease (GD), a non-neuronopathic lysosomal storage disorder, results from the deficient activity of acid beta-glucosidase (GBA). Type 1 disease is panethnic but is more prevalent in individuals of Ashkenazi Jewish (AJ) descent. Of the causative GBA mutations, N370S is particularly frequent in the AJ population, (q approximately .03), whereas the 84GG insertion (q approximately .003) occurs exclusively in the Ashkenazim. To investigate the genetic history of these mutations in the AJ population, short tandem repeat (STR) markers were used to map a 9.3-cM region containing the GBA locus and to genotype 261 AJ N370S chromosomes, 60 European non-Jewish N370S chromosomes, and 62 AJ 84GG chromosomes. A highly conserved haplotype at four markers flanking GBA (PKLR, D1S1595, D1S2721, and D1S2777) was observed on both the AJ chromosomes and the non-Jewish N370S chromosomes, suggesting the occurrence of a founder common to both populations. Of note, the presence of different divergent haplotypes suggested the occurrence of de novo, recurrent N370S mutations. In contrast, a different conserved haplotype at these markers was identified on the 84GG chromosomes, which was unique to the AJ population. On the basis of the linkage disequilibrium (LD) delta values, the non-Jewish European N370S chromosomes had greater haplotype diversity and less LD at the markers flanking the conserved haplotype than did the AJ N370S chromosomes. This finding is consistent with the presence of the N370S mutation in the non-Jewish European population prior to the founding of the AJ population. Coalescence analyses for the N370S and 84GG mutations estimated similar coalescence times, of 48 and 55.5 generations ago, respectively. The results of these studies are consistent with a significant bottleneck occurring in the AJ population during the first millennium, when the population became established in Europe.
- Lack of Cystatin B Protein as a Cause Of Myoclonic EpilepsyPublication . Amaral, O.; Duarte, A.; Pinto, E.; Freitas, J.; Chaves, J.Unverricht-Lundborg disease (ULD; MIM 254800) is the most frequent cause of progressive myoclonic epilepsy. CSTB mutations (locus 21q22.3; MIM 601145), with cystatin B loss of function and subsequent loss of lysosomal association, have been described as the major cause of this disease.
- Molecular diagnosis of Gaucher disease in TunisiaPublication . Cherif, W.; Ben Turkia, H.; Ben Rhouma, F.; Riahi, I.; Chemli, J.; Amaral, O.; Sá Miranda, M.C.; Caillaud, C.; Kaabachi, N.; Tebib, N.; Ben Dridi, M.F.[ENG] Gaucher disease is a lysosomal storage disorder caused by a deficiency of the enzyme acid b-glucosidase. In order to determine the mutation spectrum in Tunisia, we performed recurrent mutation screening in 30 Tunisian patients with Gaucher disease. Screening of recurrent mutation by PCR/RFLP and direct sequencing had shown that N370S was the most frequent mutation (22/50 mutant alleles, 44%), followed by L444P mutation, which is found in 16% (8/50 mutant alleles). The recombinant allele (RecNciI)represented 14%. Our findings revealed that the genotype N370S/RecNciI was mosst frequent in patients with childhood onset and it was associated with severe visceral involvement. The screening of these three mutations provided a simple tool for molecular diagnosis of Gaucher disease in Tunisian patients and allowed also genetic counselling for their family members.
- Mutation spectrum of Gaucher disease in Tunisia: high frequency of N370S/Rec NciI compound heterozygousPublication . Cherif, W.; Ben Turkia, H.; Tebib, N.; Amaral, O.; Ben Rhouma, F.; Abdelmoula MS, M.S.; Azzouz, H.; Caillaud, C.; Sà Miranda, M.C.; Abdelhak, S.; Ben Dridi, M.F.Gaucher disease is the most common lysosomal storage disorder, it results from the inherited deficiency of the enzyme glucocerebrosidase, the accumulation of its substrate causes many clinical manifestations. Since the discovery of GBA gene, more than 200 different mutations have been identified, but only handful mutations are recurrent (N370S, L444P and c.84insG). In order to determine the mutation spectrum in Tunisia, we performed recurrent mutation screening in ten unrelated Tunisian children with Gaucher disease. Screening of recurrent mutation by PCR/RFLP and direct sequencing, has shown that N370S is the most frequent mutation (6/20 mutant alleles, 30%), followed by recombinant allele (RecNciI) which is found in five patients (5/20 mutant alleles, 25%), the L444P mutation represent 20% (4/20 mutant alleles). Our findings revealed that five among ten studied patients, were compound heterozygous N370S/RecNciI (50%). The screening of these mutations provides a simple tool for molecular diagnosis of Gaucher disease in Tunisian patients and allows also genetic counselling for their family members.
- Mutations c.459+1G>A and p.P426L in the ARSA gene: prevalence in metachromatic leukodystrophy patients from European countriesPublication . Lugowska, A.; Amaral, O.; Berger, J.; Berna, L.; Bosshard, N.; Chabas, A.; Fensom, A.; Gieselmann, V.; Gorovenko, N.; Lissens, W.; Mansson, J.; Marcao, A.; Michelakakis, H.; Bernheimer, H.; Ol'khovych, N.; Regis, S.; Sinke, R.; Tylki-Szymanska, A.; Czartoryska, B.In this multicentre study, we examined the prevalence of two mutations in the arylsulfatase A (ARSA) gene, i.e., c.459 + 1G > A and p.P426L, in 384 unrelated European patients presenting with different types of metachromatic leukodystrophy (MLD). In total, c.459 + 1G > A was found 194 times among the 768 investigated ARSA alleles (25%), whereas p.P426L was identified 143 times (18.6%). Thus, these two mutations accounted for 43.8% of investigated MLD alleles. Mutation c.459 + 1G > A was most frequent in late-infantile MLD patients (40%), while p.P426L was most frequent in adults (42.5%), which is consistent with earlier observations, although p.P426L was also found in a few late-infantile patients (0.9%), and c.459 + 1G > A was present in some adults (9%). Mutation c.459 + 1G > A is more frequent in countries situated at the western edges of Europe, i.e., in Great Britain and Portugal, and also in Belgium, Switzerland, and Italy, which is visible as a strand ranging from North to South, and additionally in Czech and Slovak Republics. Mutation p.P426L is most prevalent in countries assembled in a cluster containing the Netherlands, Germany, and Austria. In other Central European countries, the frequency of both c.459 + 1G > A and p.P426L ranges from 8 to 37.5%. Our study has confirmed that c.459 + 1G > A and p.P426L are the most frequently found MLD-causing mutations in Europe. The data about their prevalence reflect the population variability in Europe.
- Rapid and cost-effective method for the detection of the c.533G>A mutation in the HEXA genePublication . Ribeiro, D.; Duarte, A.J.; Amaral, O.Tay-Sachs disease is a rare autosomal recessive neurodegenerative disorder that results from mutations in the HEXA gene, leading to β-hexosaminidase A (HexA) α subunit deficiency. An unusual variant of Tay-Sachs disease is known as the B1 variant. Previous studies indicated that, in northern Portugal, this is not only the most common variant but also one of the most prevalent lysosomal storage diseases. Additionally, this variant might also show a higher prevalence in populations of Portuguese and Spanish ancestry. A single mutation is invariably present in at least one of the alleles of B1 variant patients, HEXA mutation c.533G >A. To implement a method for c.533G >A testing in individuals and populations, we have optimized two distinct mutation analysis techniques, one based on restriction fragment length polymorphism analysis and the other based on allelic discrimination. We present the comparison of both methods and their advantages. Mutation screening by allelic discrimination proved to be particularly useful for the studying of large samples of individuals. It is time saving and highly reproducible, and under the conditions used, its cost is lower than the cost of polymerase chain reaction-based restriction fragment length polymorphism analysis.