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N Akar

Publications and source records attributed to N Akar.

At least 37 records · Page 2Linked to original sources
PubMed2002

Mutations of the 5alpha-steroid reductase type 2 gene in six Turkish patients from unrelated families and a large pedigree of an isolated Turkish village.

We describe six Turkish patients with 5alpha-steroid reductase type 2 deficiency from unrelated Turkish families and a large pedigree of one of these patients who reside north-west of Anatolia. Patients NA, KS, BD and SY presented for evaluation of bilateral inguinal masses with female phenotypes. Patient ABE had penoscrotal hypospadias with male phenotype. Homozygous mutation of the 5alphaSR2 gene was identified in five of these patients by genomic DNA analysis. These mutations were Leu55Gln in exon 1 (in patients FG, BD and ABE), deltaMet157 in exon 3 (in patient NA), and splice junction abnormality in intron 1 (in patient SY). One individual (patient KS) was found to be a compound heterozygous carrier of two different mutations, Leu55Gln in exon 1 and Arg171Ser in exon 3. Patient FG had a large pedigree with the Leu55Gln mutation in exon 1. The pedigree of this family with marital consanguinity is remarkable, and possibly due to the isolation of this family because of economic and social problems. A further 85 individuals belonging to this family were analyzed for exon 1 Leu55Gln mutations in the 5alphaSR2 gene. Forty-two of these 85 individuals (49.41%) had this alteration; 11 were homozygous (8 genetic male, 3 genetic female) and 31 heterozygous (18 genetic male, genetic female) for this mutation. It was interesting to see asymptomatic homozygous female carriers. In conclusion, according to our results and those of other Turkish patients reported by different investigators, 5aSR2 gene mutation analysis, especially for Leu55Gln in exon 1 and deltaMet157 in exon 3, must be carried out in Turkish patients with male pseudohermaphroditism. Homozygous asymptomatic female carriers must be taken into consideration in this clinical entity, especially in a closed population, because of the risk of transmitting the disease to their offspring.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Common mutations at the homocysteine metabolism pathway and pediatric stroke.

Heterozygosity and/or homozygosity for mutations at the genes of the enzymes involved in homocysteine metabolism may confer an increased risk for thrombosis by causing hyperhomocysteinemia. Although the mutations related to homocysteine metabolism possibly increase the risk of stroke, the data are conflicting and there are very few reports linking these defects to acute stroke in children. We aimed to study the role of these mutations in Turkish children with ischemic stroke. Forty-six patients having cerebral infarct were clinically diagnosed, and the infarction verified with magnetic resonance imaging of the brain was included in the study. All patients were below the age of 18 (10 months to 18 years). Sixty-eight controls, consecutively selected among healthy unrelated subjects from the same geographic area of Turkey without personal and family history of thrombosis, stroke or Behest's disease, were included. Genotyping for the common mutations was carried out by the methods described previously. There was no difference between the pediatric stroke patients and controls for the distribution of methylene tetrahydrofolate reductase (MTHFR) 677 C-T, MTHFR 1298 A-C, methylene tetrahydrofolate dehydrogenase (MTHFD) 1958 G-A and methionine synthase reductase (MTRR) 66 A-G alleles. There was no risk for double gene alterations (MTHFR 677 C-T vs. 1298 A-C) after individuals with FV 1691 A mutation is excluded. Twelve of the 46 patients were found to carry FV 1691 A mutation (26.0%), one being homozygote. The cerebral infarct risk for FV 1691 A was found to be 6.4 (CI 95% 1.7-23.0). Eight of the 46 patients were found to carry PT 20210 A mutation (16.6%). Two of the FV 1691 A heterozygous patients carried PT 20210 A mutation at the same time (4.2%). As a conclusion, we can say that FV 1691 A and PT 20210 A mutations are important and must be included to the routine analysis of pediatric stroke patients.

Adolescent↗
PubMed2001

The alpha2 Gene alleles of the platelet collagen receptor integrin alpha2 beta1 in Turkish children with cerebral infarct.

The possible role of point mutations in the platelet integrin alpha2 beta1 gene in Turkish children with ischemic stroke was evaluated in this study. The case-control study included 44 pediatric patients with cerebral infarct (age range, 10 months to 18 years) and 96 healthy unrelated individuals. Genotyping was performed according to previously described methods. Distribution of the three haplotypes were 36.4%, 45.3%, 10.4% and 31.8%, 50.0%, 13.6% for the controls and the patients, respectively. A new fourth haplotype was found which was 7.8% and 4.5% respectively. Our data indicated that these haplotypes are not risk factors in pediatric stroke group.

Adolescent↗
PubMed2001

Is the Ala138Gly alteration of MEFV gene important for amyloidosis?

Progressive systemic amyloidosis is the most important complication of familial Mediterranean fever that inevitably leads to chronic renal failure. Initial studies have suggested that the presence of the Met694Val mutation carry a significant risk for the development of amyloidosis. On the contrary, our data revealed that there was no dominance of any MEFV mutation in relation to amyloidosis. The difference between our mutation data and others led us to study a polymorphism in Turkish population that might be a risk factor for the occurrence of amyloidosis. As some of the previously reported exonic polymorphisms in other disease states found to increase the genetic susceptibility, we aimed to study Ala138Gly of the MEFV gene. Our study group consisted of 124 FMF patients, of which 47 had amyloidosis. Eighty-one individuals without any familial history of FMF were included as control group. There was no statistically significant difference between healthy controls and FMF patients for the Ala138Gly polymorphism (p=0.9). However, when FMF/amyloidosis patients (n:47) were taken as another group, the difference was significant (p= 0.01) indicating that the carriers of 138Gly are more prone to amyloidosis [odds ratio 3.1 (CI 95% 1.57-5.75)].

Alanine↗
PubMed2001

Methylenetetrahydrofolate reductase gene polymorphism and risk of premature myocardial infarction.

BACKGROUND: Elevated plasma homocysteine level is an independent risk factor for cardiovascular disease. A common mutation (nucleotid 677C-T) in the gene coding for methylenetetrahydrofolate reductase (MTHFR) has been reported to reduce the enzymatic activity of MTHFR and is associated with elevated plasma levels of homocysteine, especially in subjects with low folate intake. HYPOTHESIS: Methylenetetrahydrofolate reductase T/T genotype may be a risk factor for premature MI in Turkish population who are known to have low folate levels. METHODS: The study group was comprised of 96 men (aged <45 years) with premature myocardial infarction (MI) and 100 age- and gender-matched controls who had no history or clinical evidence of coronary artery disease (CAD) and/or MI. DNA was extracted from peripheral blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI, and gel electrophoresis. Conventional risk factors for CAD were prospectively documented. RESULTS: Allele and genotype frequencies among cases and control subjects were compatible with Hardy-Weinberg equilibrium. The frequencies of T/T, C/T, and C/C genotypes among patients with MI and control subjects were 15.6, 40.6, and 43.8%, and 5, 35, and 60%, respectively. Multivariate analyses identified smoking, MTHFR C/T polymorphism, diabetes mellitus, family history of CAD, and hypertension as the independent predictors of premature MI. Defining patients with non-T/T genotype (C/C and C/T combined) as reference, the relative risk of MI for subjects with T/T genotype was 5.94 (95% confidence interval: 1.96-18.02, p = 0.0016). CONCLUSIONS: Our findings suggest that C677T transition in the MTHFR gene may be a risk factor for premature MI in Turkish men.

Adult↗
PubMed2001

Connexin 26 (GJB2) mutations in the Turkish population: implications for the origin and high frequency of the 35delG mutation in Caucasians.

Mutations in the Connexin 26 (GJB2/Cx26) gene are responsible for more than half of all cases of prelingual non-syndromic recessive deafness in many Caucasian populations. To determine the importance of Cx26 mutations as a cause of deafness in Turks we screened 11 families with prelingual non-syndromic deafness, seven (64%) of which were found to carry the 35delG mutation. We subsequently screened 674 Turkish subjects with no known hearing loss and found twelve 35delG heterozygotes (1.78%; 95% confidence interval: 0.9%-3%) but no examples of the 167delT mutation. To search for possible founder effects, we typed chromosomes carrying the 35delG mutation for closely linked polymorphic markers in samples from Turkey and United States and compared the allele frequencies with those of hearing subjects. The data showed a modest degree of disequilibrium in both populations. Analyses of two pedigrees from Turkey demonstrated both conserved and different haplotypes, suggesting possible founder effects and multiple origins of the 35delG mutation.

Alleles↗
PubMed2001

A multistep process for the dispersal of a Y chromosomal lineage in the Mediterranean area.

In this work we focus on a microsatellite-defined Y-chromosomal lineage (network 1.2) identified by us and reported in previous studies, whose geographic distribution and antiquity appear to be compatible with the Neolithic spread of farmers. Here, we set network 1.2 in the Y-chromosomal phylogenetic tree, date it with respect to other lineages associated with the same movements by other authors, examine its diversity by means of tri- and tetranucleotide loci and discuss the implications in reconstructing the spread of this group of chromosomes in the Mediterranean area. Our results define a tripartite phylogeny within HG 9 (Rosser et al. 2000), with the deepest branching defined by alleles T (Haplogroup Eu10) or G (Haplogroup Eu9) at M172 (Semino et al. 2000), and a subsequent branching within Eu9 defined by network 1.2. Population distributions of HG 9 and network 1.2 show that their occurrence in the surveyed area is not due to the spread of people from a single parental population but, rather, to a process punctuated by at least two phases. Our data identify the wide area of the Balkans, Aegean and Anatolia as the possible homeland harbouring the largest variation within network 1.2. The use of recently proposed tests based on the stepwise mutation model suggests that its spread was associated to a population expansion, with a high rate of male gene flow in the Turkish-Greek area.

Alleles↗
PubMed2001

Possible effects of antioxidant status on increased platelet aggregation in childhood iron-deficiency anemia.

BACKGROUND: Alterations in platelet function and antioxidant status in children with iron-deficiency anemia (IDA) have been reported previously. The present study was performed to better understand possible interactions between these two systems. METHODS: Erythrocyte superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activity and platelet function were evaluated in 15 children (aged 1 1/2-15 years) with IDA. The antioxidant enzyme activity was determined spectrophotometrically. Platelet aggregation and secretion studies were performed using impedance and bioluminescence methods, respectively. Ten age-matched healthy children were included as a control group. RESULTS: There were no differences in SOD and CAT activities between patients and controls. However, GSH-Px activity was significantly lower in the iron-deficient children. Platelet aggregation responses to collagen and ADP were also significantly higher in iron-deficient children than in controls. CONCLUSIONS: Decreased antioxidant defense in IDA may cause increased oxidant stress, which, in turn, may result in a tendency towards platelet aggregation.

Adolescent↗
PubMed2001

Plasminogen activator inhibitor-1 4G/5G polymorphism in Turkish children with cerebral infarct and effect on factor V 1691 A mutation.

The thrombotic risk of carrying plasminogen activator inhibitor-1-675 4G allele was found to be controversial in previous studies. The aim of this study was to evaluate the possible effect of plasminogen activator inhibitor-1 4G/5G polymorphism in the pathogenesis of childhood stroke. The case-control study included 43 patients with cerebral infarct who were below the age of 18 years (range, 10 months to 18 years) and 113 healthy unrelated individuals without family histories of thrombosis. Plasminogen activator inhibitor-1 4G/5G polymorphism was analyzed according to a previously described method. There was no statistically significant difference in patient and control groups for the distribution of plasminogen activator inhibitor-1 4G/5G polymorphism (P = .75) (allele frequency 4G controls: 0.50; patients: 0.53). However, there was a significant difference for the factor V (FV) 1691 A mutation for both groups (P = .0007).

Adolescent↗
PubMed2000

The role of prothrombotic mutations in patients with Buerger's disease.

Thromboangiitis obliterans (TAO), or Buerger's disease, is a segmental occlusive inflammatory disorder of the arteries and veins, and etiopathogenesis is still obscure. In the present study we investigated the prevalence of prothrombin 20210 G-->A, factor V 1691 G-->A (Factor V Leiden), and factor V 4070 A-->G (His 1299 Arg) mutations, found to be associated with increased risk for vascular thrombosis, in 36 patients with TAO. We performed a case-control study of these mutations. The odds ratio for prothrombin 20210 A allele compared with G allele was 7.98 (95% confidence intervals 2. 45-25.93). Only this prothrombotic genetic factor was associated with the risk of TAO (p=0.032). In conclusion, carrying the prothrombin 20210 G-->A may be an important prothrombotic risk factor of TAO. This genetic predisposition must be screened in these patients routinely, and clinical importance must be supported by further investigations.

Adolescent↗
PubMed2000

Effect of plasminogen activator inhibitor-1 4G/5G polymorphism in Turkish deep vein thrombotic patients with and without FV1691 G-A.

A decreased fibrinolytic activity due to increased levels of plasminogen activator inhibitor-1 has been shown in deep vein thrombosis patients. Elevated plasma plasminogen activator inhibitor-1 levels are associated with the 4G allele of a 4G/5G polymorphism located in the promoter region of the plasminogen activator inhibitor-1 gene. Because there is no existing data in the Turkish population, we aimed to study these mutations in patients with deep vein thrombosis (n = 136) and normal controls (n = 113), consecutively selected among unrelated healthy subjects without personal and familial history of atherothrombosis from Ankara, Turkey. DNA was extracted by conventional methods, and polymerase chain reaction of the plasminogen activator inhibitor-1 4G/5G polymorphism was performed according to a previously described method. Genotype distributions of FV 1691G-A and plasminogen activator inhibitor-1 4G/5G are as follows: plasminogen activator inhibitor-1 4G (patients) 0.562, plasminogen activator inhibitor-1 4G (controls) 0.50 (p = 0.6); FV1691A (patients) 0.147, FV1691A (controls) 0.035 (p = 0.005). Our data indicated that plasminogen activator inhibitor-1 4G/5G does not have an effect on the thrombotic risk. Carrying the 4G allele either in heterozygous or homozygous state increases the risk in the presence of FV1691A (odds ratio: 9.8 and 6.9, confidence interval 95% 2.9-32.7 and 1.3-35.8). FV1691A is an independent risk factor for thrombosis (odds ratio: 5.5, confidence interval: 95% 2.5-12.1). We concluded that coexistence of FV1691A and plasminogen activator inhibitor-1 4G allele leads to an increased risk for thrombosis leading a further evidence to another prothrombotic factor that may be necessary for the development of a manifest thrombotic event.

Adult↗