Browsing by Author "DE SOUSA, M."
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- Clinical and genetic heterogeneity in hereditary haemochromatosis: association between lymphocyte counts and expression of iron overloadPublication . Porto, Graça; CARDOSO, C.S.; GORDEUK, V.; CRUZ, E.; FRAGA, J.; AREIAS, J.; OLIVEIRA, J.C.; BRAVO, F.; GANGAIDZO, I.T.; MACPHAIL, A.P.; GOMO, Z.A.; MOYO, V.M.; MELO, G.; SILVA, C.; JUSTICA, B.; DE SOUSA, M.Eur J Haematol. 2001 Aug;67(2):110-8. Clinical and genetic heterogeneity in hereditary haemochromatosis: association between lymphocyte counts and expression of iron overload. Porto G, Cardoso CS, Gordeuk V, Cruz E, Fraga J, Areias J, Oliveira JC, Bravo F, Gangaidzo IT, MacPhail AP, Gomo ZA, Moyo VM, Melo G, Silva C, Justiça B, de Sousa M. Haematology, Santo António General Hospital, Porto, Portugal. gporto@ibmc.up.pt Abstract To identify a new marker of expression of disease, independent of HFE genotype in patients with hereditary haemochromatosis (HHC), the total peripheral blood lymphocyte counts were analysed according to iron status in two groups of subjects with HFE mutations. The groups consisted of 38 homozygotes for C282Y, and 107 heterozygotes for the C282Y or compound heterozygotes for C282Y and H63D. For control purposes, total lymphocyte counts and iron status were also examined in 20 index patients with African dietary iron overload, a condition not associated with HFE mutations, and in 144 members of their families and communities. Mean lymphocyte numbers were lower in C282Y homozygous HHC index subjects with cirrhosis and higher iron stores than in those without cirrhosis and with lower iron burdens [(1.65 +/- 0.43) x 10(6)/mL vs. (2.27 +/- 0.49) x 10(6)/mL; p = 0.008]. Similarly, mean lymphocyte counts were significantly lower in C282Y heterozygotes and C282Y/H63D compound heterozygotes with iron overload and increased serum ferritin concentrations compared to those with normal serum ferritin concentrations (p < 0.05). Statistically significant negative correlations were found, in males, between lymphocyte counts and the total body iron stores, either in C282Y homozygous HHC patients (p = 0.031 in a multiple regression model dependent on age) and in C282Y heterozygotes or C282Y/H63D compound heterozygotes with iron overload (p = 0.029 in a simple linear model). In contrast, lymphocyte counts increased with increasing serum ferritin concentrations among the index subjects with African iron overload (r = 0.324, not statistically significant) and among the members of their families and communities (r = 0.170, p = 0.042). These results suggest that a lower peripheral blood lymphocyte count is associated with a greater degree of iron loading in HFE haemochromatosis but not in African iron overload, and they support the notion that the lymphocyte count may serve as a marker of a non-HFE gene that influences the clinical expression of HFE haemochromatosis.
- Low serum transferrin levels in HFE C282Y homozygous subjects are associated with low CD8(+) T lymphocyte numbers.Publication . MACEDO, M.F.; CRUZ, E.; LACERDA, R.; PORTO, G.; DE SOUSA, M.Blood Cells Mol Dis. 2005 Nov-Dec;35(3):319-25. Epub 2005 Sep 1. Low serum transferrin levels in HFE C282Y homozygous subjects are associated with low CD8(+) T lymphocyte numbers. Macedo MF, Cruz E, Lacerda R, Porto G, de Sousa M. SourceDivision of Human Genetics and Genetic Disorders, Iron Genes and the Immune System Laboratory, Institute for Molecular and Cell Biology (IBMC), Oporto, Portugal. Abstract Hereditary hemochromatosis (HH) is a genetic iron overload disease, in the majority of cases associated with homozygosity for the C282Y mutation of the HFE gene. In spite of this genetic homogeneity, there is a great clinical heterogeneity among HH patients. Low CD8(+) lymphocyte numbers have been associated with a more severe expression of iron overload in HH patients, and in experimental models of iron overload. HH patients present low serum transferrin levels. Transferrin is an indispensable resource for lymphopoiesis. Lymphocyte homeostasis follows general ecology rules of population dynamics that involve competition for limiting resources. In the present study, we questioned whether transferrin levels could be associated with the anomalies seen previously in lymphocyte subset numbers in HH patients. Transferrin levels, total and subset T lymphocyte counts were done in 426 apparently healthy subjects genotyped for HFE. All HFE C282Y carriers presented significantly lower serum transferrin levels than the wild type group, a difference that could not be explained solely by the degree of iron overload. Significant differences were also seen in transferrin levels between males and females, with females presenting higher average serum Transferrin levels. In the population of subjects with Transferrin levels lower than 248 mg/dl, a positive correlation was seen between the peripheral CD8(+) lymphocyte numbers and serum transferrin levels (R(2) = 2.41; r = 0.16; P = 0.018). To test the possible limiting resource effect of transferrin, the correlation between transferrin levels and CD8(+) lymphocyte numbers was scrutinized in 34 HH patients, homozygous for the C282Y mutation. In the homozygous males, where the lowest average transferrin levels were seen, another highly significant correlation was observed between Transferrin levels and CD8(+) numbers. This correlation points to a possible role of transferrin as a limiting resource for MHC class I dependent lymphocyte proliferation, an effect that was not observed in C282Y homozygous female patients. PMID: 16140024 [PubMed - indexed for MEDLINE]
- Major histocompatibility complex class I associations in iron overload: evidence for a new link between the HFE H63D mutation, HLA‐A29, and non‐classical forms of hemochromatosis.Publication . PORTO, G.; ALVES, H.; RODRIGUES, P.; CABEDA, J.M.; PORTAL, C.; RUIVO, A.; JUSTICA, B.; WOLFF, R.; DE SOUSA, M.Immunogenetics. 1998 Apr;47(5):404-10. Major histocompatibility complex class I associations in iron overload: evidence for a new link between the HFE H63D mutation, HLA-A29, and non-classical forms of hemochromatosis. Porto G, Alves H, Rodrigues P, Cabeda JM, Portal C, Ruivo A, Justiça B, Wolff R, De Sousa M. Santo António General Hospital, Largo do Prof. Abel Salazar, no.1, P-4050 Porto, Portugal. Abstract The present study is an analysis of the frequencies of HFE mutations in patients with different forms of iron overload compared with the frequencies found in healthy subjects from the same region. The frequencies of HLA-A and -B antigens and HLA haplotypes were also analyzed in the same subjects. The study population included: 71 healthy individuals; 39 genetically and clinically well-characterized patients with genetic hemochromatosis (HH); and 25 patients with non-classical forms of iron overload (NCH), excluding secondary hemochromatosis. All subjects were HLA-typed and HFE-genotyped by the oligonucleotide ligation assay (OLA). The gene frequencies found for the C282Y and H63D mutations of HFE were respectively: 0.03 and 0.23 in healthy individuals, 0.86 and 0.04 in HH patients, and 0.08 and 0.48 in NCH patients. An expected significant association between HH and HLA-A3 was observed, which was found to be in linkage disequilibrium with the C282Y mutation. A new association was seen, however, between HLA-A29 and NCH, in linkage disequilibrium with the H63D mutation. Again as expected, the HLA-B antigen B7 was associated with HH in linkage disequilibrium with HLA-A3. In addition, the HLA-B antigen B44 was found to be associated with NCH but not in linkage disequilibrium with either A29 or the H63D mutation. In conclusion, a new association of the HFE H63D mutation with forms of hemochromatosis other than HH and a new association between the HLA phenotype A29 and the HFE H63D mutation were found in the same patients. These findings reinforce evidence for the involvement of the major histocompatibility class I in iron metabolism, supporting the notion of a physiological role for the immunological system in the regulation of iron load. PMID: 9510559 [PubMed - indexed for MEDLINE]
- T cell numbers relate to bone involvement in Gaucher diseasePublication . LACERDA, L.; AROSA, F.A.; LACERDA, R.; CABEDA, J.; PORTO, G.; AMARAL, O.; Fortuna, A.; PINTO, R.; OLIVEIRA, P.; MCLAREN, C.E.; SA MIRANDA, C.; DE SOUSA, M.Blood Cells Mol Dis. 1999 Apr;25(2):130-8. T cell numbers relate to bone involvement in Gaucher disease. Lacerda L, Arosa FA, Lacerda R, Cabeda J, Porto G, Amaral O, Fortuna A, Pinto R, Oliveira P, McLaren CE, Sá Miranda C, de Sousa M. Department of Genetics Neurobiology, Porto University, Portugal. Abstract The major elements of bone pathology in Gaucher disease are a failure of osteoclast and osteoblast function, resulting in osteopenia and also osteonecrosis. T lymphocytes have recently been found to be involved in the regulation of osteoblast/osteoclast activity in vitro. In the present report the peripheral blood T major lymphocyte subsets were investigated in a group of genotyped type 1 Gaucher disease patients. A total of 31 patients were studied: 21 non-splenectomized (5 N370S homozygotes) and 10 splenectomized (of whom 1 was a N370S homozygote). The results show that non-splenectomized patients present a decrease in absolute numbers of peripheral blood T lymphocytes, specially the CD4+ T subset. However, when patients were analyzed with respect to the presence of bone disease, the number of CD8+ T lymphocytes was found to be statistically significantly lower in patients presenting bone involvement. Furthermore, lower numbers of CD8+ T lymphocytes were significantly correlated with higher levels of plasma tartrate resistant acid phosphatase (TRAP) activity, a putative marker of osteoclast cell activity. These in vivo findings are in agreement with the results reached in vitro by others. They provide an additional marker of disease severity in Gaucher disease. In the group of genotyped Gaucher disease patients, the majority of the N370S homozygous patients presented a clinically milder phenotype, including the absence of bone involvement, confirming earlier reports predicting that a number of these patients may remain undiagnosed. Collectively the homozygosity for the N370S mutation and normal T cell numbers may provide additional markers for the clinical heterogeneity of Gaucher disease. PMID: 10389595 [PubMed - indexed for MEDLINE
- Transferrin receptor 2 (TfR2) and HFE mutational analysis in non‐C282Y iron overload: identification of a novel TfR2 mutationPublication . MATTMAN, A.; HUNTSMAN, D.; LOCKITCH, G.; LANGLOIS, S.; BUSKARD, N.; RALSTON, D.; BUTTERFIELD, Y.; RODRIGUES, P.; JONES, S.; PORTO, G.; MARRA, M.; DE SOUSA, M.; VATCHER, G.Blood. 2002 Aug 1;100(3):1075-7. Transferrin receptor 2 (TfR2) and HFE mutational analysis in non-C282Y iron overload: identification of a novel TfR2 mutation. Mattman A, Huntsman D, Lockitch G, Langlois S, Buskard N, Ralston D, Butterfield Y, Rodrigues P, Jones S, Porto G, Marra M, De Sousa M, Vatcher G. SourceGenes, Elements, and Metabolism Program, Children and Women's Hospital of British Columbia, Vancouver, British Columbia, Canada. Abstract Hereditary hemochromatosis (HH) is classically associated with a Cys282Tyr (C282Y) mutation of the HFE gene. Non-C282Y HH is a heterogeneous group accounting for 15% of HH in Northern Europe. Pathogenic mutations of the transferrin receptor 2 (TfR2) gene have been identified in 4 Italian pedigrees with the latter syndrome. The goal of this study was to perform a mutational analysis of the TfR2 and HFE genes in a cohort of non-C282Y iron overload patients of mixed ethnic backgrounds. Several sequence variants were identified within the TfR2 gene, including a homozygous missense change in exon 17, c2069 A-->C, which changes a glutamine to a proline residue at position 690. This putative mutation was found in a severely affected Portuguese man and 2 family members with the same genotype. In summary, pathologic TfR2 mutations are present outside of Italy, accounting for a small proportion of non-C282Y HH.