Association of insertion/deletion polymorphism of the angiotensin-converting enzyme gene with angio-oedema accompanying chronic urticaria but not chronic urticaria without angio-oedema or the autologous serum skin test response.

BACKGROUND: Chronic urticaria is defined as the daily or almost daily occurrence of weals for more than 6 weeks. The underlying pathophysiology is reported to be mast cell activation, with release of mast cell mediators, predominantly histamine. Substance P is a neuropeptide and has the capacity to provoke histamine release from skin mast cells. Angiotensin-converting enzyme (ACE), widely expressed in skin, is one of the major peptidase for the degradation of substance P. An insertion/deletion polymorphism (I/D) in the ACE gene has been reported to be related to the levels of enzyme. OBJECTIVE: An increase in substance P levels due to a polymorphism in ACE gene might be related to the pathology. Thus, we aimed to investigate whether there is an association between ACE I/D polymorphism and chronic ordinary urticaria. METHODS: Ninety-five patients with chronic ordinary urticaria were recruited and divided into two groups according to autologous serum skin test status and accompanying angio-oedema. One hundred and sixty-one healthy subjects were enrolled as control group. All participants were genotyped for I/D polymorphism in intron 16 of the ACE gene by polymerase chain reaction. RESULTS: A statistically significant association was not found between ACE I/D polymorphism and chronic ordinary urticaria. Further analyses of chronic ordinary urticaria patients showed that ACE I/D polymorphism was not associated with autologous serum skin test status of patients. However, the frequencies of II genotype and I allele were statistically significantly higher in chronic ordinary urticaria patients with accompanying angio-oedema with regard to angio-oedema-negative patients (II genotype: 24% vs. 9%, P = 0.0002; I allele: 58% vs. 27%, P = 0.0001) and control group (II genotype: 24% vs. 19%, P = 0.01; I allele: 58% vs. 41%, P = 0.03). CONCLUSION: The results of this study suggest no evidence of an association between ACE I/D polymorphism and risk of developing chronic ordinary urticaria. However, it can be a contributing factor to susceptibility of angio-oedema in chronic ordinary urticaria.

Arylamine N-acetyltransferase (NAT2) genotypes in a Turkish population.

A group of 303 unrelated Turkish subjects from south-east Anatolia was genotyped for seven NAT2 mutations by polymerase chain reaction-restriction fragment length polymorphism. Genotypes associated with slow acetylation were identified in 57.4% (95%-confidence limits, 51.6%-63.1%). Allele frequencies were NAT2*4 (wild type, 23.1%), *5A (1.3%), *5B (35.6%), *5C (4.8%), *6A (30.5%), *7B (4.5%), and *12A (0.2%). A mutation G191A was not detected. Ambiguous mutation linkages were checked by molecular genetic linkage analysis and DNA sequencing. NAT2-alleles in Turks are similarly distributed as in Middle European ethnicities.

Low frequency of defective alleles of cytochrome P450 enzymes 2C19 and 2D6 in the Turkish population.

BACKGROUND AND OBJECTIVES: The genetically polymorphic cytochrome P450 enzymes 2Cl9 (CYP2Cl9) and 2D6 (CYP2D6) contribute to the metabolism of about 30% of all drugs. For analysis of the ethnic-related differences in drug disposition and as a preparation for routine genotyping, we examined CYP2C19 and CYP2D6 mutations in a large Turkish population. METHODS: CYP2C19 and CYP2D6 alleles were determined with use of genomic deoxyribonucleic acid from 404 unrelated Turkish individuals. CYP2C19 alleles *1 to *5 and CYP2D6 alleles *1 to *12, and *14, *15, and *17 were measured by polymerase chain reaction-restriction fragment length polymorphism assays. RESULTS: From 404 subjects genotyped for CYP2C19, allele frequencies of CYP2C19*1 (wt), CYP2C19*2 (ml), and CYP2C19*3 (m2) were 0.88, 0.12, and 0.004, respectively; mutations m3 and m4 were not found. Four individuals (1.0%) were predicted to be poor metabolizers (CYP2C19*2/*2), a significantly lower frequency compared to Middle European populations. Among 404 subjects genotyped for CYP2D6, most frequent alleles were CYP2D6*1 (allele frequency 0.37), *2 (0.35), *4 (0.11), *10 (0.06), duplications *1x2, *2x2, or *4x2 (0.06), *5 (0.01), and *17(0.01). Overall, six subjects (1.49%) were predicted to be CYP2D6 poor metabolizers, and 35 subjects (8.66%) were predicted to be ultrarapid metabolizers as a result of CYP2D6 gene duplications. CONCLUSION: Obviously, within Europe there is a north-south gradient, with decreasing frequency of poor metabolizers of CYP2C19 and CYP2D6 to the south and a corresponding increase of ultrarapid metabolizers of CYP2D6. As in other white groups, only CYP2C19*2 plays a relevant role for the CYP2C19 poor metabolizer phenotype. The mutational spectrum of CYP2D6 indicated partial ethnic relationships to Asian and African populations.

Cytochrome P4502C9 genotype in Southeast Anatolia and possible relation with some serum tumour markers and cytokines.

Substrates for CYP2C9 include fluoxetine, phenytoin, warfarin, losartam and numerous nonsteroidal anti-inflammatory drugs. Polymorphisms in the coding region of the CYP2C9 gene produce variants at amino-acid residues 144 Arg/Cys and 359 Ile/Leu of the CYP2C9 protein. Individuals homozygous for Leu359 have markedly diminished metabolic capacities for most CYP2C9 substrates, the frequency of this allele is, however, rather low. Consistently with the modulation of enzyme activity by genetic and other factors, wide interindividual variability occurs in the elimination and/or dosage requirements of prototypic CYP2C9 substrates. The polymorphic enzyme CYP2C9 takes part in the metabolism of alkylating agents and polycyclic aromatic hydrocarbons like benzo(a)pyrene, a carcinogen present in tobacco smoke. Although the impact of impaired enzyme activity in metabolism of carcinogens and procarcinogens has not been fully defined, an association of CYP2C9 variant alleles to DNA adduct levels in lung tissues as well as to lung cancer risk have been reported. In this study 64 healthy subjects (44M/22F) were analysed for CYP2C9 genotype with PCR-RFLP and for serum carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), CA 19-9, CA 15-3, ferritin, IL-6, IL-8 concentrations by chemiluminescence or electrochemiluminescence methods. CYP2C9*1 was found to be the most prevalent allele and CYP2C9*1/CYP2C9*1 was the most frequent genotype represented in 64% of the population in southeastern Anatolia (Gaziantep). Although slight differences in serum tumour marker and cytokine concentrations were observed for CYP2C9 genotypes the differences were statistically insignificant (P > 0.05). This could be due to the complexity of the role of CYP2C9 in benzo(a)pyrene metabolism as well as from other contributing factors like interindividual variability of diverse enzymes participating in the same metabolic pathway, unequal expression of the variant alleles and differences in exposure to carcinogens. However, determination of CYP2C9 phenotypes in a larger group of subjects might clarify these slight differences.

The human paraoxonase Gln-Argl92 (Q/R) polymorphism in turkish patients with coronary artery disease.

It has been suggested that a Q/R (Glnl92Arg) polymorphism of paraoxonase (PON) might be associated with the predisposition to coronary artery disease (CAD). Therefore, we studied the human paraoxonase gene (PON1) polymorphism in Turkish patients with CAD by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). This polymorphism was determined in 96 CAD patients and in 105 control subjects. The frequencies of the QQ, QR, and RR genotypes were found as 36.5, 52.0, and 11.5% in CAD patients and 48.6, 41.0, and 10.4% in control subjects, respectively. The QR genotype was the most common in the patient group, whereas the QQ genotype was more frequent in individuals without CAD. Frequency of the R allele was higher among CAD patients compared to controls (38.5% versus 31%). However, neither the genotype nor the allele distribution of the Gln92Arg polymorphism of PON1 was statistically significantly different between the two groups (P>0.05). Although both systolic and diastolic blood pressure levels were slightly higher in patients with the QQ genotype, there was no differences in regard to age, sex, serum triglyceride, total cholesterol or high-density lipoprotein cholesterol among CAD patients with different PONI Gln192Arg genotypes. In summary, our results suggest that no association exists between the Gln192Arg polymorphism of paraoxonase and CAD in Turkish patients.

Association of the Gln27Glu polymorphism of the beta-2-adrenergic receptor with preterm labor.

OBJECTIVES: To investigate a potential association between the beta-2-adrenergic receptor (B2AR) polymorphisms occurring at amino acid positions 16 (Arg16Gly) and 27 (Gln27Glu) and preterm labor. METHODS: Eighty patients with preterm labor and 76 control subjects were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: A significant association was found between Gln27Glu substitution and preterm labor (P=0.001). The frequency of Gly16 and Glu27 alleles were found to be higher in patients than in control women (0.54 vs. 0.48 and 0.42 vs. 0.26, respectively), and the odds ratio for the occurrence of preterm labor was 2.14 (95% CI, 1.32-3.46; P=0.002) for the Glu 27 allele. An early delivery was noted in 52.5% of patients. CONCLUSION: The Gln27Glu polymorphism of the B2AR gene may have a role in molecular pathogenesis of preterm labor. Glu27 allele in patients with preterm labor might be a risk factor for deliveries before 37 weeks of gestation.

Citalopram-induced photopigmentation.

Citalopram is one of the newer and most potent selective serotonin re-uptake inhibitor (SSRI) drugs. It has a well-established antidepressive action with a favorable adverse event profile. We present a fifty-year-old woman with diffuse photopigmentation who had been diagnosed as suffering from depression. The patient was given citalopram (40 mg/day) for her psychiatric condition and diffuse photopigmentation was noted thereafter. To our knowledge, such an adverse event has not been reported previously.

The impact of acute dynamic exercise on intraocular pressure: role of the beta 2-adrenergic receptor polymorphism.

Effects of mutations in the beta 2-adrenergic receptor (beta 2AR) gene on intraocular pressure (IOP), in response to acute dynamic exercise, were investigated in 19 healthy males (age 22.6 +/- 2.8 years). Intraocular pressures were measured pre- and post-exercise. Weight, height, body mass index, and maximal oxygen (VO2max) uptake were recorded and subjects were genotyped for Arg16Gly, Gln27Glu and Thr164Ile mutations of the beta 2AR gene. Post-exercise, reductions in mean IOP values were found in 16 subjects with the Gly16Gly and Arg16Gly genotypes, but these values remained low in the eight patients with the Gly16Gly genotype 3 h post-exercise, whereas they returned to baseline within 1 h in the eight subjects with the Arg16Gly genotype. beta 2AR stimulation during exercise could be an important regulator of IOP response and determining beta 2AR polymorphisms may improve understanding of pathogenesis and treatment selection in ophthalmic diseases, e.g. glaucoma.

Association of insertion/deletion polymorphism of the angiotensin-converting enzyme gene with psoriasis.

BACKGROUND: Genetic factors are likely to be of fundamental importance in the pathogenesis of psoriasis. There are reports concerning the induction or/and exacerbation of psoriasis by angiotensin-converting enzyme (ACE) inhibitors, which have been attributed to the ACE inhibitor-induced augmentation of kinin levels in skin. However, to the best of our knowledge there has been no molecular genetic study investigating whether ACE insertion/deletion (I/D) polymorphism may contribute to the genetic background in psoriasis. OBJECTIVES: To assess the role of ACE I/D polymorphism in psoriasis. METHODS: A group of 86 patients with psoriasis and 154 control subjects were analysed for ACE I/D polymorphism by polymerase chain reaction. RESULTS: The distribution of ACE I/D polymorphism and allele frequencies in psoriatic patients was not significantly different from controls. Further analyses of psoriasis patients showed that ACE I/D polymorphism was not associated with age at onset of disease, clinical type of psoriasis or gender. However, the frequency of the I allele was significantly higher in patients with a positive family history of psoriasis than in those with no family history (sporadic psoriasis) (48% vs. 32%; P =0.03). In addition, the I allele was found significantly more frequently in type I psoriasis patients (onset < 40 years and positive family history) than in type II psoriasis patients (onset >/= 40 years, no family history) (48% vs. 27%; P = 0.04). CONCLUSIONS: Our results suggest that the presence of the I allele may confer susceptibility to development of psoriasis in individuals from psoriatic families.

High frequency of CYP1A1 mutations in a Turkish population.

The frequency distribution of four cytochrome P4501A1 (CYP1A1) gene mutations was investigated in 271 Turks from southeast Anatolia by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) assay. Allelic linkage of those mutations was proven by peptide nucleic acid-mediated PCR clamping. Mutation ml (T6235C) forming an MspI restriction site in the 3'-flanking region occurred with 18.1% frequency (95% confidence interval 14.9-21.6%), m2 (A4889G) leading to an Ile/Val exchange in exon 7 had a frequency of 8.9% (6.6-11.6%), and m4 (C4887A; Thr/Asn-exchange also in exon 7) occurred with 5.7% (3.9-8.0%). T5639C (m3) in the 3'-flanking region was not detected. m2 was exclusively found linked with ml forming allele CYP1A1*2B. The frequency of this allele supposedly at-risk for lung cancer was significantly higher than in Middle European populations, but lower than in the Far East.

Frequency of cytochrome P450 CYP2C9 variants in a Turkish population and functional relevance for phenytoin.

AIMS: The genetically polymorphic cytochrome P450 enzyme CYP2C9 metabolizes many important drugs. We studied the frequency of the amino acid variants cysteine144 (CYP2C9*2 ) and leucine359 (CYP2C9*3 ) in a Turkish population and the correlation between genotype and phenotype using phenytoin as probe drug. METHODS: CYP2C9 alleles *2 and *3 were measured in 499 unrelated Turkish subjects by PCR and restriction fragment length pattern analysis. Phenotyping was performed in a subgroup of 101 volunteers with a single oral dose of 300 mg phenytoin and concentration analysis in serum drawn 12 h after dosage. RESULTS: CYP2C9 allele frequencies in 499 unrelated Turkish subjects were 0.794 for CYP2C9*1, 0.106 for CYP2C9*2 and 0. 100 for CYP2C9*3. Mean phenytoin serum concentrations at 12 h after dosage were 4.16 mg l-1 (95% CI 3.86-4.46) in carriers of the genotype CYP2C9*1/1, 5.52 mg l-1 (4.66-6.39) in CYP2C9*1/2, and 5.65 mg l-1 (4.86-6.43) in CYP2C9*1/3. These differences were significant and accounted for 31% of total variability in phenytoin trough levels. Mean 12 h concentration ratios of 5-(para-hydroxyphenyl)-5-phenylhydantoin/phenytoin (p-HPPH/P) were 0. 43 (0.39-0.47) for CYP2C9*1/1 compared with 0.26 (0.21-0.31) for CYP2C9*1/2, 0.14 (0.13-0.14) for CYP2C9*2/2, 0.21 (0.18-0.24) for CYP2C9*1/3, and 0.02 for CYP2C9*3/3; all mutant genotypes were significantly different compared with CYP2C9*1/1. CONCLUSIONS: Frequency of the two CYP2C9 variants in Turkish subjects was in a similar range as in other Caucasian populations. A significant proportion of the interindividual variability in phenytoin trough levels is explained by the genotypes. The 12 h serum concentrations after a single phenytoin dose may be used for routine phenotyping of CYP2C9 mediated metabolic clearance and the p-HPPH/P ratios may be even more sensitive indicators of CYP2C9 activity.

Paraoxonase 1 mutations in a Turkish population.

Human serum paraoxonase 1 (PON1) catalyzes the hydrolysis of certain organophosphate pesticides and nerve gases and so may alter significantly an individual's susceptibility to the toxicity of these chemicals. Moreover, PON1 hydrolyzes lipid peroxides complexed to low density lipoproteins (LDL) and therefore it was suggested that PON1 may be one of the genes that is involved in the pathogenesis of cardiovascular diseases. Its activity shows interindividual and interethnic variability. At least two mutation sites, namely Gln192Arg (Q/R) and Leu55Met (L/M) were reported responsible for the variations in enzyme activity. The aim of the present study was to determine the frequency of these mutations in Turks and compare the results with other European and Oriental populations. A total of 381 unrelated Turkish individuals were genotyped for Gln192Arg and Leu55Met polymorphisms by PCR-RFLP using AlwI and NlaIII, respectively. Genotype distribution was QQ = 0.49, QR = 0.40, RR = 0.11, and LL = 0.52, LM = 0.39, MM = 0.09. Thus frequencies of high activity alleles R (Arg) and L (Leu) were found as 0.31 and 0.72, respectively. The frequency of these alleles was slightly higher in Turkish subjects than other Caucasian populations but much lower compared to Oriental populations.

Population frequency, mutation linkage and analytical methodology for the Arg16Gly, Gln27Glu and Thr164Ile polymorphisms in the beta2-adrenergic receptor among Turks.

AIMS: Inherited polymorphisms of codons 16, 27, and 164 of the beta2-adrenergic receptor (B2AR) gene may result in significantly changed functions of this receptor. The aim of the present study was to investigate the frequencies of the main mutations of the B2AR gene in Turks. METHODS: A group of 104 unrelated Turkish subjects were analysed for the Arg16Gly, Gln27Glu, and Thr164Leu polymorphisms of B2AR by a newly designed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. A 242-bp amplicon including the Arg16Gly and Gln27Glu polymorphisms was generated including an arbitrary restriction site, allowing the cleavage with Eco130I or Fnu4HI for analysis of the two polymorphic sites, respectively. For the amino acid polymorphism at codon 164 a 280-bp fragment was generated and digested by MnlI. RESULTS: The allelic frequencies of mutated Gly16, Glu27, and Ile164 alleles were found as 59.6%, 31.7%, and 0.5%, respectively. Although, the frequencies of the polymorphisms at codon 16 and 164 were found similar as in various Caucasian populations, the frequency of the Glu27 variant was found significantly lower than these populations. CONCLUSIONS: Obviously there are interethnic differences in functionally relevant B2AR variants which may have implications for drug treatment and disease susceptibility.

N-acetyltransferase polymorphism in patients with Behçet's disease.

OBJECTIVES: The objective of our study was to investigate the possible role of human arylamine N-acetyltransferase 2 (NAT2) polymorphism in susceptibility to Behçet's disease. METHODS: Eighty-five patients with Behçet's disease gave their written informed consent to participate in the study. Seven point mutations (G191A, C282T, T341C, C481T, A803G, G590A, G857A) in the NAT2 gene were analysed using polymerase chain reaction/restriction fragment length polymorphism techniques. In addition, each patient received 100 mg dapsone orally to determine their NAT2 phenotype. Dapsone and its metabolite monoacetyl-dapsone were measured in 3-h plasma samples using high-performance liquid chromatography. Subjects with an acetylation ratio (monoacetyl-dapsone/dapsone) less than 0.4 were defined as slow acetylators. RESULTS: Of 85 patients with Behçet's disease, 54 (63.5%) were identified as genotypically slow acetylators. However, 60% (51 of 85) of patients were diagnosed as slow acetylators according to monoacetyl-dapsone/dapsone ratio. Thus, a low incidence of genotype/phenotype discrepancy (3.5%) was observed in Turkish patients with Behcet's disease. When we compared our results with previous phenotyping and genotyping studies in the Turkish population, frequencies of slow and rapid acetylators were not statistically different in patients with Behçet's disease. The frequency of the *5B allele was found to be slightly higher in patients with Behçet's disease than historic controls (44.7 vs 35.6%, P = 0.039). However, there was no significant difference in the frequency of the overall genotypes and alleles of NAT2 between patients and controls. CONCLUSION: Although the frequency of the NAT2*5B allele, responsible for slow acetylation, was slightly higher in patients than historic controls, our results failed to show an association between NAT2-acetylator status and risk for developing Behçet's disease.

The predictive value of MDR1, CYP2C9, and CYP2C19 polymorphisms for phenytoin plasma levels.

Phenytoin, an anticonvulsant, exhibits nonlinear pharmacokinetics with large interindividual differences. Because of its small therapeutic range with the risk of therapeutic failure or adverse drug effects in susceptible persons, therapeutic drug monitoring is frequently applied. The interindividual differences in dose response can partially be explained by known genetic polymorphisms in the metabolic enzyme CYP2C9 but a large deal of individual variability remains still unexplained. Part of this variability might be accounted for by variable uptake of phenytoin, which is a substrate of p-glycoprotein, encoded by the human MDR1 gene. We evaluated, whether phenytoin plasma levels correlate with a polymorphism in the MDR1 gene, C3435T, which is associated with intestinal PGP activity. Genotyping and analyses of plasma levels of phenytoin and metabolites in 96 healthy Turkish volunteers showed that the MDR1C > T3435 polymorphism affects phenytoin plasma levels (P = 0.064) and the metabolic ratio of p-HPPH vs phenytoin (MDR1*TT genotype, P = 0.026). The MDR1*CC genotype is more common in volunteers with low phenytoin levels (P < or = 0.001, chi2 test). A combined analysis of variable alleles of CYP2C9, 2C19 and MDR1 revealed that the number of mutant CYP2C9 alleles is a major determinant, the number of MDR1*T alleles further contributes to the prediction of phenytoin plasma levels and CYP2C19*2 does not explain individual variability. The regression equation that fitted the data best included the number of mutant CYP2C9 and MDR*T alleles as predictory variables and explained 15.4% of the variability of phenytoin data (r2 = 0.154, P = 0.0002). Furthermore, analysis of CYP2C9 and MDR1 genotypes in 35 phenytoin-treated patients recruited from therapeutic drug monitoring showed that combined CYP2C9 and MDR1 analysis has some predictive value not only in the controlled settings of a clinical trial, but also in the daily clinical practice.