SS - Sistema Sanguíneo (Doenças do sangue, orgãos hematopoiéticos e linfopoiéticos)
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- HFE mutations in patients with hereditary haemochromatosis in SwedenPublication . Cardoso, E.; Stal, P.; Hagen, K.; Cabeda, J.; Esin, S.; Sousa, M.; Hultcrantz, R.OBJECTIVE: To determine the frequency of mutations (C282Y and H63D) in a newly identified gene HFE in patients with hereditary haemochromatosis (HH) in Sweden. DESIGN: Molecular genetic analyses of the HFE gene (polymerase chain reaction (PCR) followed by enzyme restriction) were performed in genomic DNA from unrelated patients with a clinical diagnosis of HH and in healthy subjects. SETTINGS: Patients with HH treated with phlebotomies at Karolinska Hospital and Huddinge Hospital were analyzed. SUBJECTS: Eighty-seven unrelated patients with HH and 117 healthy controls. RESULTS: It was found that the HFE C282Y mutation occurs in 94.2% of chromosomes from patients with HH. Eighty patients (92.0%) were homozygous for the C282Y mutation and one was heterozygous. Three patients were heterozygous for both C282Y and H63D mutations. One patient was homozygous and one was heterozygous for the H63D mutation. One patient carried normal alleles. In healthy controls, the C282Y mutation occurred in nine subjects (7.7%), all of which were heterozygous. The H63D mutation was found in 28 control subjects, one of which was homozygous. CONCLUSIONS: We found that the majority of patients with HH have the C282Y mutation in the HFE gene. The frequency of the H63D mutation was higher in controls than in patients with HH, although in chromosomes at risk the frequency of the H63D mutation was higher in patients.
- Advances in the genotyping of thrombosis genetic risk factors: clinical and laboratory implications.Publication . Cabeda, J.; Pereira, M.; Oliveira, J.; Estevinho, A.; Pereira, I.; Morais, S.; Justiça, B.; Campos, M.Since FV-Leiden polymorphism was first described in 1994, a growing number of polymorphic loci have been identified in association with increased genetic risk for thrombophilia. Often however, these risk factors have been studied in isolation of the remaining known phenotype linked polymorphisms. This fact has, at least in part, been justified by the laborious techniques traditionally used in the genotyping studies, as well as its relatively high costs. Another major problem concerning these studies has been the non-negligible incidence of dubious genotypes, resulting from the manual, labour intensive techniques applied, and their sometimes difficult to read output's. These difficulties have also hampered the widespread use of genotyping data in the clinical assessment of the genetic risk levels both in patients and their relatives, leaving some clinicians less than convinced about its clinical usefulness. Recently however, the introduction of new genetic techniques in the clinical genetics laboratory has started to change this picture. Most notably, the advent of Real-time-PCR has brought the possibility of genotyping patients and controls at a large scale, with increased specificity, automation and speed. Moreover, the use of these techniques in the clinical genetics setting has not only increased the quality of the results, but most importantly has also increased our capability of answering questions at a deeper level. Among the new questions that can now be answered without increased costs and uncertainty is the study of the association of genetic risk factors in thrombophilia. Our results show that indeed even common polymorphic loci may increase our ability to further discriminate the genetic thrombosis risk of individual patients and relatives. It must however be noted that the innovation level in the clinical genetics lab is just starting to grow. In fact we haven't even started to experience the advantages brought about by the genome program, and its massive identification of SNP's. The technology to test these is also presently being refined, and is expected to go from research to the clinical lab in the near future. Only then, can we expect to define with high certainty the combined genetic risks for such complex pathologies as the thrombophilias.
- Co-selection of the H63D mutation and the HLA-A29 allele: a new paradigm of linkage disequilibrium?Publication . Cardoso, C.; Alves, H.; Mascaranhas, M.; Gonçalves, R.; Oliveira, P.; Rodrigues, P.; Cruz, E.; Sousa, M.; Porto, G.The major histocompatibility complex (MHC) shows a remarkable conservation of particular HLA antigens and haplotypes in linkage disequilibrium in most human populations, suggesting the existence of a convergent evolution. A recent example of such conservation is the association of particular HLA haplotypes with the HFE mutations. With the objective of exploring the significance of that association, the present paper offers an analysis of the linkage disequilibrium between HLA alleles or haplotypes and the HFE mutations in a Portuguese population. Allele and haplotype associations between HLA and HFE mutations were first reviewed in a population of 43 hemochromatosis families. The results confirmed the linkage disequilibrium of the HLA haplotype HLA-A3-B7 and the HLA-A29 allele, respectively, with the HFE mutations C282Y and H63D. In order to extend the study of the linkage disequilibrium between H63D and the HLA-A29-containing haplotypes in a normal, random population, an additional sample of 398 haplotypes was analyzed. The results reveal significant linkage disequilibrium between the H63D mutation and all HLA-A29-containing haplotypes, favoring the hypothesis of a co-selection of H63D and the HLA-A29 allele itself. An insight into the biological significance of this association is given by the finding of significantly higher CD8+ T-lymphocyte counts in subjects simultaneously carrying the H63D mutation and the HLA-A29 allele.
- Bilateral orbital masses in a patient with B-cell chronic lymphPublication . Coelho, H.; Guerra, M.; Teixeira, M.; Canelhas, A.; Pinto-Ribeiro, A.; Lima, M.
- The soluble transferrin receptor as a marker of iron homeostasis in normal subjects and in HFE-related hemochromatosisPublication . Brandâo, M.; Oliveira, J.; Bravo, F.; Reis, J.; Garrido, I.; Porto, G.Background and Objectives. The soluble transferrin receptor (sTfR) is a clinical marker of erythropoietic activity, also used in the diagnosis of iron deficiency. In the present paper we explore the meaning of this parameter in normal physiological conditions of iron homeostasis and in the setting of iron overload due to hereditary hemochromatosis (HH). Design and Methods. Reference values for sTfR were established in a population of 42 apparently healthy subjects, analyzed in relation to other hematologic parameters, namely, hemoglobin (Hb), mean corpuscular volume (MCV), transferrin saturation (TfSat) and serum ferritin. The same analysis was done in a group of 45 patients with HH who were homozygous for the C282Y mutation of HFE and had a wide range of TfSat values. In addition, individual serial profiles were analyzed in three patients. Results. In normal subjects circulating sTfR correlated significantly with the TfSat level, reflecting the systemic effect of iron availability on the erythropoietic activity in a normal physiological steady state. A TfSat of 25% appeared as a threshold value, below which there was a progressive increase in sTfR; this increase in sTfR occurred concomitantly with a decrease in Hb, MCV and serum ferritin. In HH patients the up-regulation of sTfR started at TfSat values as high as 50%. Interpretation and Conclusions. The fact that sTfR up-regulation started at higher TfSat values in HH patients suggests that the recognition of systemic iron available for erythropoiesis is altered in this condition. Based on these results, a new hypothesis is advanced, proposing that the HFE protein in involved as a sensor of systemic iron availability, via the soluble transferrin receptor.
- Isoimunização Rh a Múltiplos AntigéniosPublication . Mesquita, S.; Proença, E.; Alexandrino, A.RESUMO A doença hemolítica perinatal isoimune (DHP) resulta da destruição dos eritrócitos fetais e do recém-nascido por anticorpos maternos dirigidos especificamente contra os antigénios de membrana dessas células. Os autores apresentam um caso de isoimunização Rh a antigénios múltiplos, anti-C, D e E, num 2º filho de um casal com antecedentes de abortamento espontâneo e um 1º filho com DHP anti- CDE e necessidade de transfusão permuta. Apesar da gravidade, com necessidade de várias transfusões- permuta e concentrados de plaquetas, a doença acabou por evoluir favoravelmente. O evento sensibilizante desta isoimunização terá sido o abortamento, sete anos antes, em que não foi feita profilaxia anti-D. O principal objectivo na DHP é, sempre que possível, a prevenção da isoimunização primária e a identificação precoce dos casos em que a isoimunização já ocorreu. A propósito deste caso, são discutidos os factores envolvidos na falência da prevenção e os responsáveis pela sua gravidade. Os autores concluem que o erro humano constitui um dos principais factores implicados no aparecimento e gravidade da maioria dos casos de DHP. ABSTRACT The haemolytic perinatal isoimune disease (HPD) results from the destruction of fetal and newborn erythrocytes by maternal antibodies directed specifically against membrane antigens of those cells. The authors present a case of Rh isoimmunization by multiple antigens, anti-C, D and E, in a second offspring of a couple which previously had had a spontaneous abortion, and then a first offspring with HPD anti-CDE who needed an exchange transfusion. Despite the severity of the disease, requiring several exchange transfusions and platelet transfusions, the outcome was favourable. The event responsible for this isoimmunization was the previous spontaneous abortion, which was not followed by anti-D prophylaxis. In the management of the HPD the main goals are the prevention of primary isoimmunization and the early identification of those cases in which isoimmunization already occurred. In the reference case we discuss the factors responsible for the failure in the prevention and for its severity. The authors conclude that human error remains one of the main factors responsible for the majority of the DHP cases and its severity.
- The spectrum of mutations and molecular pathogenesis of hemophilia A in 181 Portuguese patientsPublication . David, D.; Ventura, C.; Moreira, I.; Diniz, M.; Antunes, M.; Tavares, A.; Araújo, F.; Morais, S.; Campos, M.; Lavinha, J.; Kemball-Cook, G.Disease-causing alterations within the F8 gene were identified in 177 hemophilia A families of Portuguese origin. The spectrum of non-inversion F8 mutations in 101 families included 67 different alterations, namely: 36 missense, 8 nonsense and 4 splice site mutations, as well as 19 insertions/deletions. Thirty-four of these mutations are novel. Molecular modeling allowed prediction of the conformational changes introduced by selected amino acid substitutions and their correlation with the patients' phenotypes. The relatively frequent, population-specific, missense mutations together with de novo alterations can lead to significant differences in the spectrum of F8 mutations among different populations
- A study of 82 extended HLA haplotypes in HFE-C282Y homozygous hemochromatosis subjects: relationship to the genetic control of CD8+ T-lymphocyte numbers and severity of iron overloadPublication . Cruz, E.; Vieira, J.; Almeida, S.; Lacerda, R.; Gartner, A.; Cardoso, C.; Alves, H.; Porto, G.Abstract BACKGROUND: It has been recently demonstrated that CD8+ T-lymphocyte numbers are genetically transmitted in association with the MHC class I region. The present study was designed with the objective of narrowing the region associated with the setting of CD8+ T-lymphocyte numbers in a population of C282Y homozygous hemochromatosis subjects, in whom a high prevalence of abnormally low CD8+ T-lymphocyte counts has been described. METHODS: The study includes 43 C282Y homozygous subjects fully characterized both phenotypically and genotypically. Clinical characterization includes measurements of iron parameters at diagnosis (transferrin saturation and serum ferritin), total body iron stores and T-cell immunophenotyping determined by flow cytometry. Genetic characterization includes HLA class I alleles (A, B and C) and four additional microsatellite markers (D6S265, D6S2222, D6S105 and D6S2239) spanning 5 Megabases in the 6p21.3 region. RESULTS: Eighty-two extended C282Y carrying haplotypes were defined. Single-locus analysis revealed that the HLA-A region was associated with CD8+ T-cell numbers. Multivariate analysis showed that the combinations of the most common HLA-A alleles (HLA-A*03, -A*02 and -A*01) were associated with significantly lower numbers of CD8+ T-lymphocytes (0.30 +/- 0.14 x 106/ml), in comparison with subjects carrying only one copy of those alleles (0.46 +/- 0.19 x 106/ml) and subjects without any copy of those alleles (0.79 +/- 0.15 x 106/ml;p = 0.0001). No differences were observed in CD8+ T-cell counts among control subjects carrying the same combinations of HLA-A alleles (0.47 +/- 0.14; 0.45 +/- 0.21 and 0.41 +/- 0.17 x 106/ml, respectively), therefore not supporting a direct effect of HLA specificity but rather an indirect association with a locus close to HLA-A. Multivariate analysis showed that the combination of the most common HLA-A alleles also have an impact on the clinical expression of HH in terms of iron stores, in males(p = 0.0009). CONCLUSION: The present study provides evidence supporting an inextricable link between extended HLA haplotypes, CD8+ T-lymphocyte numbers and severity of iron overload in hereditary hemochromatosis(HH). It gives additional information to better define a candidate region involved in the regulation of CD8+ T-lymphocyte numbers. A new evolutionary hypothesis concerning the inheritance of the phenotype of low CD8+ T-lymphocyte numbers associated with particular ancestral HLA haplotypes carrying the C282Y mutation and its implication on the clinical heterogeneity of HH is discussed.
- A new 500 kb haplotype associated with high CD8+ T-lymphocyte numbers predicts a less severe expression of hereditary hemochromatosisPublication . Cruz, E.; Whittington, C.; Krikler, S.; Mascarenhas, C.; Lacerda, R.; Vieira, J.; Porto, G.Abstract BACKGROUND: Hereditary Hemochromatosis(HH) is a common genetic disorder of iron overload where the large majority of patients are homozygous for one ancestral mutation in the HFE gene. In spite of this remarkable genetic homogeneity, the condition is clinically heterogeneous, varying from a severe disease to an asymptomatic phenotype with only abnormal biochemical parameters. The recent recognition of the variable penetrance of the HH mutation in different large population studies demands the need to search for new modifiers of its phenotypic expression. The present study follows previous observations that MHC class-I linked genetic markers, associated with the setting of CD8+ T-lymphocyte numbers, could be clinically relevant modifiers of the phenotypic expression in HH, and aimed to find new markers that could be used as more reliable prognostic variables. METHODS: Haplotype analysis, including seven genetic markers within a 1 Mb region around the microsatellite D6S105 was performed in a group of 56 previously characterized C282Y homozygous Portuguese patients. Parameters analyzed in this study were total body iron stores, clinical manifestations related with HH and immunological parameters (total lymphocyte numbers, CD4+ and CD8+ T-lymphocyte numbers). An independent group of 10 C282Y homozygous patients from Vancouver, Canada, were also included in this study and analyzed for the same parameters. RESULTS: A highly conserved ancestral haplotype defined by the SNP markers PGBD1-A, ZNF193-A, ZNF165-T (designated as A-A-T) was found associated with both abnormally low CD8+ T-lymphocyte numbers and the development of a severe clinical expression of HH. In a small proportion of patients, another conserved haplotype defined by the SNP markers PGBD1-G, ZNF193-G, ZNF165-G (designated as G-G-G) was found associated with high CD8+ T-lymphocyte numbers and a milder clinical expression. Remarkably, the two conserved haplotypes defined in Portuguese patients were also observed in the geographically different population of Canadian patients, also predicting CD8+ T-lymphocyte numbers and the severity of disease. CONCLUSION: These results may have important implications not only for approaching the question of the penetrance of the hemochromatosis gene in different world populations but also to further narrow the region of interest to find a candidate gene involved in the setting of CD8+ T-lymphocyte numbers in humans.
- LINFOMAS CUTÂNEOS DE CÉLULAS T: PAPEL DAS CÉLULAS NK E T CIRCULANTES NA DEFESA ANTI-TUMORALPublication . Aguiar, A.; Queirós, M.; Alves, R.; Lima, M.O cancro é uma doença complexa caracterizada por um crescimento descontrolado de células próprias do organismo. O sistema imune tem a capacidade de identificar estas células e desenvolver mecanismos de forma a elimina-las. Na tentativa de melhorar o conhecimento sobre como o sistema imune reage perante a presença de células neoplásicas, têm sido realizados numerosos estudos, envolvendo diferentes tipos de tumores. Os linfomas cutâneos de células T (LCCT), grupo de patologias malignas caracterizado pela proliferação de linfócitos T (LT) na pele, têm sido alvos destes estudos. Contudo, embora alguns demonstrem que as células imunológicas intervêm ao longo da evolução da doença, este assunto é ainda controverso.