H2AX gene does not have a modifier effect on ataxia-telangiectasia phenotype.

Ataxia-telangiectasia (AT) is a complex disorder characterized by progressive neurodegeneration, immunodeficiency, hypersensitivity to DNA damaging agents and cancer predisposition. Clinical heterogeneity is observed even among the affected siblings with AT. Mutations of the ataxia-telangiectasia mutated (ATM) gene are responsible for AT. H2AX, an essential histone protein, is phosphorylated by ATM in response to double-strand breaks, and H2AX-deficient mice share some clinical and laboratory findings with AT. Therefore, we sought a possible modifier effect of H2AX gene on various clinical features in a group of patients with AT and healthy controls. We performed sequence analysis of H2AX gene in 81 patients with AT, and in 51 of them, we analysed methylation. We examined H2AX gene expression in 25 patients. We investigated 48 healthy individuals as a control group. We did not detect any mutation or sequence variation in the H2AX gene, or any altered methylation pattern in any of the patients. Although H2AX gene expression was markedly increased (2.5- to 11.8-fold) in five of 25 patients, and slightly increased (1.5- to 2.4-fold) in four patients, the correlations between H2AX gene expression and the evaluated clinical features of the patients were not significant. Other potential modifier genes that might be scrutinized in AT patients include p53, 53BP1 and TIP60, as well as the genes that effect mitochondrial function and the oxidative response.

Mutation spectrum of fumarylacetoacetase gene and clinical aspects of tyrosinemia type I disease.

Tyrosinemia type I (OMIM 276700) is a rare, autosomal recessive disorder caused by a deficiency in the fumarylacetoacetate hydrolase (FAH) enzyme. This study examined the spectrum of FAH gene mutation in 32 patients with tyrosinemia type I. In addition, clinical and biochemical findings were evaluated to establish a genotype-phenotype relationship in the patients. Mutation screening was performed using a 50K custom-designed resequencing microarray chip (TR_06_01r520489, Affymetrix) and sequencing analysis. Of the 12 different mutations found, 6 are categorized as novel. Three of the mutations-IVS6-1G>A, D233V, and IVS3-3C>G-are the most common in Turkish patients, comprising 25%, 17.1%, and 12.5% of mutant alleles, respectively.Clinical evaluations suggest that the spectrum of symptoms observed in the patients with very early and early disease were of the more nonspecific form, whereas the patients with late-presenting disease had more of the distinctive form over the course of the disease. This study adds support to the notion that the D233V mutation is specific to the Turkish population.

DRB1, DQA1, DQB1 genes in Turkish children with rheumatic fever.

OBJECTIVES: Several studies have suggested that genetic susceptibility to rheumatic fever (RF) may be linked to HLA Class II alleles. The purpose of this study was to examine the association between HLA Class II genes and RF in Turkish children. METHODS: DNA typing HLA Class II genes (DRB1, DQA1, DQB1) were performed in 55 children with RF and 50 healthy unrelated controls using sequence specific primers (SSP). RESULTS: The frequency of the HLA DQA1*03 (OR: 0.462, p < 0.05) allele was significantly decreased in the patient group. Also, the frequency of the combination of DRB1*04 and DQA1*03 allele (OR: 0.42, p < 0.01) was more significantly decreased in the patient group. Differences in frequencies of the DRB1 and DQB1 alleles between groups were not significant. CONCLUSIONS: Our data indicate that the HLA DQA1*03 allele may be a protecting factor in Turkish children with RF. Our results also suggest that the combination of the DRB1*04 and DQA1*03 alleles may be a stronger protective factor than the DQA1*03 allele alone.

Thrombomodulin levels in Behçet's disease with and without the factor V Leiden mutation.

The plasma levels of thrombomodulin (TM) in 34 patients with Behçet's disease and 79 healthy control subjects were studied. Eight patients had the factor V Leiden (FVL) mutation. The TM level was significantly lower in patients with the FVL mutation than in patients without the mutation and in the healthy controls (p < 0.05 and p < 0.01). However, there was no difference in overall mean plasma TM concentration between the patients without the mutation and the healthy controls.

Factor V Leiden mutation in patients with Behçet's disease.

OBJECTIVE: To determine the relation between factor V Leiden and Behçet's disease (BD), which is described as chronic relapsing vasculitis with pathogenetic mechanisms that seem to be related to anticoagulant pathways. METHODS: Using polymerase chain reaction, the factor V Leiden mutation was investigated in 44 patients with BD, of which 5 had thrombotic histories. RESULTS: Ten patients were found to have the factor V Leiden mutation. This frequency (22.7%) was higher than that of our general population (7.1 %) (p < 0.05). Of the 5 patients with BD with thrombotic histories, 3 (60%) had factor V Leiden mutation (one homozygote, 2 heterozygote), while 7 of 39 (17.9%) patients with no thrombotic history had the factor V Leiden mutation (2 homozygotes, 5 heterozygotes). There is no statistical difference in the frequency of the factor V mutation between patients with BD with no thrombosis and the control group. The frequency of thrombosis in BD with and without factor V Leiden mutation was (3/10) 30% and (2/34) 5.9%, respectively. CONCLUSION: These findings suggest that homozygosity or heterozygosity for factor V Leiden is not always associated with occurrence of venous thrombosis in BD, but it may be a contributing risk factor for venous thromboembolic events in these patients.

The prevalence of factor V Leiden (1691 G-->A) mutation in Turkey.

Resistance to activated protein C (APC), which is caused by a single point mutation in the gene for factor V, is a common risk factor for thrombosis. In this study, we screened factor V (FV) Leiden mutation in 81 subjects. The mutation in the heterozygous form was found in 7.1 percent of our normal population. This high frequency suggests that screening for the FV mutation should be considered in patients with a family history of thrombosis.

Genotype-phenotype analysis in HbS-beta-thalassemia.

Genotypes and phenotypes were studied in 31 Turkish HbS-beta-thalassemia patients. In 19 patients the beta-thalassemia mutations were beta+ and in 12 the beta 0 phenotype. The IVSI-110 mutation was found in 45% of the patients. IVSI-1, beta 39, IVSII-1 and FSC8 are the genotypes associated with beta 0-thalassemia. Hematological data were evaluated at the time of diagnosis and 4 years after diagnosis. The mean HbF value was 13 +/- 7.8% at diagnosis and 9.7 +/- 7.8% 4 years later. A significant negative correlation was observed between the age of the patients and the HbF value (p < 0.05). No statistically significant differences were observed between the mean of hematological parameters in beta(+)- and beta 0-thalassemia patients except for the mean HbF value which were 10.7 +/- 6.9 and 15.9 +/- 7.7% in beta(+)- and beta 0-thalassemia, respectively (p < 0.05). The study indicated that beta-thalassemia mutations in trans to the HbS mutation do not exert any beneficial effect on the manifestation of the disease.

Factor V Q 506 mutation in children with thrombosis.

The factor V Leiden mutation in 12-children with thrombosis and in 20 controls was investigated. Five heterozygous individuals and 1 homozygous individual among the cases with thrombosis and 1 heterozygous individual among controls were found. Central nervous system thromboses were increased in children with the factor V mutation, associated with protein S deficiency.

Prenatal diagnosis of hemoglobinopathies in Turkey: Hacettepe experience.

Prenatal diagnosis of hemoglobinopathies was performed in 250 fetuses at risk for hemoglobinopathies. The main diagnostic procedures were in vitro hemoglobin synthesis analysis in fetal blood and analysis of DNA obtained from chorionic villus samples. Sixty-six percent of the fetuses were at risk for beta thalassemia major and 28% for sickle cell anemia. Beta thalassemia mutations were heterogenous, and 51 fetuses examined by the DNA technique were found to be at risk for at least 20 different combinations.

Prenatal diagnosis of sickle cell anemia using PCR and restriction enzyme Dde I.

Prenatal diagnosis of sickle cell anemia was carried out in four fetuses using DNA technology. Fetal chorionic villus specimen were obtained at the 10th week of pregnancy from women at risk of giving birth to children with sickle cell anemia. Whole cellular DNA was obtained and the part of the DNA presumed to have a mutation increased after PCR was performed. After the application of Dde I restriction enzyme, mini gel electrophoresis was performed. The study of the electrophoretic patterns of the DNA indicated that one of the four fetuses was unaffected, one was a carrier and the remaining two were affected.