Association between methylene tetrahydrofolate reductase and glutathione S-transferase M1 gene polymorphisms and chronic myeloid leukemia in a Brazilian population.

Chronic myeloid leukemia is a hematopoietic stem cell disorder that causes uncontrolled proliferation of white blood cells. Although the clinical and biological aspects are well documented, little is known about individual susceptibility to this disease. We conducted a case-control study analyzing the prevalence of the polymorphisms MTHFR C677T, MTHFR A1298C, del{GSTM1}, del{GSTT1}, and haptoglobin in 105 patients with chronic myeloid leukemia (CML) and 273 healthy controls, using PCR-based methods. A significant association with risk of developing CML was found for MTHFR 1298AA (odds ratio (OR) = 1.794; 95% confidence interval (CI) = 1.14-2.83) and GSTM1 non-null (OR = 1.649; 95%CI = 1.05-2.6) genotypes, while MTHFR 1298AC (OR = 0.630; 95%CI = 0.40-0.99) and GSTM1 null (OR = 0.606; 95%CI = 0.21-0.77) genotypes significantly decreased this risk. There appeared to be selection for heterozygosity at the MTHFR 1298 locus. The considerable range of variation in this and other human populations may be a consequence of distinctive processes of natural selection and adaptation to variable environmental conditions. The Brazilian population is very mixed and heterogeneous; we found these two loci to be associated with CML in this population.

CD47 expression is decreased in hematopoietic progenitor cells in patients with myelofibrosis.

Myelofibrosis (MF) is characterized by increased circulating hematopoietic progenitor cells (HPCs), abnormal cytokine levels, and the survival advantage of neoplastic progenitors over their normal counterparts, which leads to progressive disappearance of polyclonal hematopoiesis. CD47 is a surface glycoprotein with many functions, such as acting as a phagocytosis inhibitor of the expressing cell, that is increased in normal hematopoietic stem and progenitor cells mobilized into the blood and several human cancer-initiating cells, such as in acute myeloid leukemia. We compared CD47 expression in hematopoietic stem and progenitor cells of patients with MF and controls and found it to be decreased in progenitors of MF. Exposure of control HPCs to the cytokines transforming growth factor ß and stromal-derived factor 1, which are important regulators of hematopoietic stem cell cycling and are overexpressed in patients with MF, did not modulate CD47 expression.

High frequency of mutation G377S in Brazilian type 3 Gaucher disease patients.

Gaucher disease (GD), the most prevalent lysosome storage disorder, presents an autosomal recessive mode of inheritance. It is a paradigm for therapeutic intervention in medical genetics due to the existence of effective enzyme replacement therapy. We report here the analysis of GD in 262 unrelated Brazilian patients, carried out in order to establish the frequency of the most common mutations and to provide prognostic information based on genotype-phenotype correlations. Among 247 type 1 GD patients, mutation N370S was detected in 47% of all the alleles, but N370S/N370S homozygosity was found in only 10% of the patients, a much lower frequency than expected, suggesting that most individuals presenting this genotype may not receive medical attention. Recombinant alleles were detected at a high frequency: 44% of the chromosomes bearing mutation L444P had other mutations derived from the pseudogene sequence, present in 25% of patients. Three neuronopathic type 2 patients were homozygous for L444P, all presenting additional mutations (E326K or recombinant alleles) that probably lead to the more severe phenotypes. Six children, classified as type 1 GD patients, had a L444P/L444P genotype, showing that neuronopathic symptoms may only manifest later in life. This would indicate the need for a higher treatment dose during enzyme replacement therapy. Finally, mutation G377S was present in 4 homozygous type 1 patients and also in compound heterozygosity in 5 (42%) type 3 patients. These findings indicate that G377S cannot be unambiguously classified as mild and suggest an allele-dose effect for this mutation.

[Reagudization of Chagas myocarditis inducing exclusive right ventricular failure]. / Reagudização de cardite chagásica provocando insuficiência ventricular direita exclusiva.

Woman, 42 years-old, receiving immunosuppressive therapy for a lymphoma, presented reagudization of Chagas' disease, from its indeterminate phase. Intense inflammatory visceral aggression, due to extensive intracellular proliferation of the Trypanosoma cruzi, was the likely mechanism for acute myocarditis leading to severe right ventricular failure. Antiparasite chemotherapy was effective in the control of visceral involvement and for the remission of cardiac failure. The clinical course in this case is compatible with the hypothesis of early right ventricular damage in Chagas' disease.

CD47 expression is decreased in hematopoietic progenitor cells in patients with myelofibrosis

Myelofibrosis (MF) is characterized by increased circulating hematopoietic progenitor cells (HPCs), abnormal cytokine levels, and the survival advantage of neoplastic progenitors over their normal counterparts, which leads to progressive disappearance of polyclonal hematopoiesis. CD47 is a surface glycoprotein with many functions, such as acting as a phagocytosis inhibitor of the expressing cell, that is increased in normal hematopoietic stem and progenitor cells mobilized into the blood and several human cancer-initiating cells, such as in acute myeloid leukemia. We compared CD47 expression in hematopoietic stem and progenitor cells of patients with MF and controls and found it to be decreased in progenitors of MF. Exposure of control HPCs to the cytokines transforming growth factor β and stromal-derived factor 1, which are important regulators of hematopoietic stem cell cycling and are overexpressed in patients with MF, did not modulate CD47 expression.

High frequency of mutation G377S in Brazilian type 3 Gaucher disease patients

Gaucher disease (GD), the most prevalent lysosome storage disorder, presents an autosomal recessive mode of inheritance. It is a paradigm for therapeutic intervention in medical genetics due to the existence of effective enzyme replacement therapy. We report here the analysis of GD in 262 unrelated Brazilian patients, carried out in order to establish the frequency of the most common mutations and to provide prognostic information based on genotype-phenotype correlations. Among 247 type 1 GD patients, mutation N370S was detected in 47 percent of all the alleles, but N370S/N370S homozygosity was found in only 10 percent of the patients, a much lower frequency than expected, suggesting that most individuals presenting this genotype may not receive medical attention. Recombinant alleles were detected at a high frequency: 44 percent of the chromosomes bearing mutation L444P had other mutations derived from the pseudogene sequence, present in 25 percent of patients. Three neuronopathic type 2 patients were homozygous for L444P, all presenting additional mutations (E326K or recombinant alleles) that probably lead to the more severe phenotypes. Six children, classified as type 1 GD patients, had a L444P/L444P genotype, showing that neuronopathic symptoms may only manifest later in life. This would indicate the need for a higher treatment dose during enzyme replacement therapy. Finally, mutation G377S was present in 4 homozygous type 1 patients and also in compound heterozygosity in 5 (42 percent) type 3 patients. These findings indicate that G377S cannot be unambiguously classified as mild and suggest an allele-dose effect for this mutation.