Department of Medical Biology, Faculty of Medicine, Suleyman Demirel University, 32260 Cunur, Isparta, Turkey, nilufersahin@yahoo.com.

Mutations in the ganglioside-induced differentiation-associated protein 1 gene (GDAP1) cause Charcot-Marie-Tooth type 2 (CMT2), a severe autosomal recessive form of neuropathy associated with axonal phenotypes. It has been screened in this study for the presence of mutations in the coding region of GDAP1, which maps to chromosome 8q21, in a family with CMT2. To date, 29 mutations in the GDAP1 have been reported in patients of different ethnic origins. Here, we report a novel missense mutation (c.836A>G), and two polymorphisms: a silent variant (c.102G>C), and a 5′-splice site mutation (IVS5+24C>T) in GDPA1 gene identified in a five generation Turkish family with autosomal recessive CMT2.

Department of Medical Biology, Faculty of Medicine, Ankara University, Ankara, Turkey guvemg@yahoo.com.

Human P-glycoprotein (P-gp) is encoded by the MDR1 gene, which is located on chromosomal region 7q21 and consists of 28 exons. To date, over 50 single nucleotide polymorphisms (SNPs) have been reported for the MDR1 gene. The effect of these polymorphisms on P-gp function or their clinical impact is in most cases unknown, but some of the SNPs are known to be of functional relevance and can also alter the pharmacokinetics of substrate drugs. The aim of the current study was to analyze for the first time an existing silent MDR1 C1236T (Gly412Gly) polymorphism in a Turkish population. The genotype frequencies of C1236T SNP in a Turkish population were also compared with those in other populations. One hundred unrelated healthy subjects (48 females, 52 males) were included in this study and all them were of Turkish ethnicity. The genotyping of the C1236T SNP was performed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. The frequencies of the wild-type C and mutant T alleles were 45.5 and 54.5%, respectively. The distribution of C1236T genotype frequencies in our study group was found to be similar to that in Czech, Polish, Portuguese, Russian, Malay, and Japanese populations and different from that in French, German, Chinese, and Indian populations. The distributions of CC, CT, and TT genotypes were 20.0, 51.0, and 29.0%, respectively. Our study provides a framework for future studies concerning the role of polymorphic variants of MDR1 gene in the genesis of various diseases or in designing future pharmacogenetic and pharmacokinetic studies conducted with P-gp substrates in the Turkish population.

Department of Endocrinology and Metabolism Disease, Ege University Medical School, Bornova, Izmir, Turkey. drmerdogan61@yahoo.com

OBJECTIVE: Interleukin-10 (IL-10) is a major anti-inflammatory cytokine that plays a crucial role in the regulation of the immune system. Chronic inflammation has been reported to be a risk factor for thyroid neoplasia. The propensity to mount an inflammatory response is modified by germ line variation in cytokine and other inflammation-related genes. We hypothesized that a proinflammatory genotype would be positively associated with thyroid cancer. We aimed to evaluate the relation between the genotypic and allelic frequencies of the IL-10(-1082 G/A), IL-10(-592 A/C), and IL-10(-819 C/T) polymorphisms, and their association with the risk of developing papillary thyroid cancer (PTC) in the Turkish population. RESEARCH DESIGN AND METHODS: Forty-two patients with PTC and 113 healthy controls were included in this study. The diagnosis of PTC was confirmed by histopathologic examination after surgery. The evaluation of genotype for IL-10 gene polymorphism was performed using PCR-restriction fragment length polymorphism method. RESULTS: Statistically significant difference IL-10(-1082 G/A) gene polymorphism was determined between 2 (PTC and control) groups. No difference was determined with respect to IL-10(-592 A/C) and IL-10(-819 C/T) gene polymorphisms, and IL-10(-1082 G/A), IL-10(-592 A/C), and IL-10(-819 C/T) allele frequencies of participating between the control group and the patients with PTC (p>0.05). CONCLUSIONS: The polymorphism of IL-10(-1082 G/A) gene was significantly associated with the occurrence of PTC. Such studies will contribute significantly to our understanding of the biological role of IL-10(-1082 G/A) gene polymorphism in PTC development. In conclusion, IL-10(-1082 G/A) gene polymorphism may affect the survival of papillary thyroid carcinoma.

Gazi University, Faculty of Medicine.

Genetic and environmental factors are involved in Prostate Cancer (PCa) etiology. Single nucleotide polymorphisms (SNPs) may contribute to the PCa pathogenesis. The goal of this study is to determine the role of vitamin D receptor (VDR) gene polymorphisms and haplotypes in the development and progression of sporadic PCa. One hundred and thirty-three PCa patients and one hundred and fifty-seven age-matched healthy controls were genotyped for the ApaI (rs7975232), BsmI (rs1544410) and TaqI (rs731236) polymorphisms in VDR gene by using polymerase chain reaction-restriction fragment length polymorphism. An association was observed between the ApaI polymorphism and PCa predisposition (P = 0.03). When compared with AA genotype, there was a highly notable difference in the frequencies of the Aa (P = 0.02), aa (P = 0.026) and ApaI “a” allele carriers (Aa+aa) (P = 0.009) genotypes. Furthermore, we found a statistical difference in the allele frequencies of the ApaI polymorphism between the sporadic PCa patients and control subjects (P = 0.013). The genotype distribution for the BsmI and TaqI polymorphisms were similar between cases and controls (P >0.05). No clinically significant relationship was found between the three-locus haplotypes and development of sporadic PCa. The genotype frequencies for the three polymorphisms of the VDR gene within subgroups of PCa (defined by tumor stage, Gleason score, PSA levels) were also analyzed, but no statistically noteworthy difference was observed (P >0.05). As far as we know, this is the first study which investigates the relationship between VDR genotypes and sporadic PCa in the Turkish Population. Our findings suggest that the VDR ApaI (rs7975232) polymorphism may play a role in the development of sporadic PCa.

Institute of Clinical Pharmacology, Charité-Universitätsmedizin Berlin, Humboldt University of Berlin, Schumannstrasse 20/21, 10098 Berlin, Germany.

BACKGROUND: OATP1B1 is one of the key hepatocellular uptake transporters providing extraction of diverse compounds, including bile acids, xenobiotics, and a variety of drugs, from portal venous blood into the liver. Polymorphisms of the SLCO1B1 gene have been demonstrated to influence in vitro transport function and the pharmacokinetic profile of compounds. OBJECTIVE: The goal of our study was the comparison of SLCO1B1 gene sequence variability in three ethnic groups as a basis for future genetic association studies. METHODS: Eighteen exonic SLCO1B1 single nucleotide polymorphisms (SNPs) were genotyped by PCR and RFLP analysis in 300 German, 94 Turkish, and 115 African subjects. Calculation of pairwise linkage disequilibrium and estimation of population haplotype frequencies were carried out, and haplotype block structure was determined. RESULTS: Only eight genotyped SNPs (c.388A>G, c.411G>A, c.463C>A, c.521T>C, c.571C>T, c.597C>T, c.1463G>>C, c.1929A>C) were found in at least one of our German, Turkish, or African samples. A total of 12 haplotypes with a frequency >or=1% in at least one of the three populations could be inferred. Between the Caucasian and African samples, significant differences in sequence variability were observed leading to a different haplotype profile in these populations. CONCLUSION: Our results demonstrate a high sequence variability of OATP1B1 within different popuations. In the future, distinct haplotypes should be taken into account when studying the effect of OATP1B1 on drugs in different populations.

Department of Periodontology, Faculty of Dentistry, Baskent University, Ankara, Turkey. esragd@yahoo.com

Localized aggressive periodontitis (LAgP) is a complex multifactorial periodontal disease to which genetic factors are thought to predispose individuals. Interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) are potent immunomodulators and proinflammatory cytokines that have been implicated in the pathogenesis of autoimmune and infectious diseases and proposed to be risk factors for LAgP. Our aim was to investigate IL-1 alpha (+4845), IL-1 beta (+3954), and TNF-alpha (-308) gene polymorphisms in Turkish LAgP patients. We genotyped 31 LAgP patients and 31 healthy controls for IL-1alpha(+4845), IL-1beta(+3954), and TNF-alpha(-308) using standard PCR amplification followed by restriction enzyme digestion and gel electrophoresis. Higher prevalence of heterozygosity for IL-1alpha(+4845) was found in cases (65%) when compared to controls (35%) (P < 0.05). While homozygous allele 1 of IL-1beta(+3954) was the most frequent genotype in cases (62%), no controls were homozygous for this allele (P < 0.001). Homozygous allele 1 was the most common TNF-alpha genotype in both groups, however no significant difference in TNF-alpha genotypes was found between groups. In conclusion, in this Turkish population, susceptibility to LAgP is increased by heterozygosity for allele 1 of IL-1alpha(+4845) or homozygosity for allele 1 of IL-1beta(R+3954). Moreover, IL-1 gene polymorphisms appear to have a role in susceptibility to LAgP, and the above-mentioned genotypes could be an important risk factor for LAgP in the Turkish population.

Institute for Molecular & Human Genetics, Georgetown University, Washington, DC 20007, USA.

Insulin receptor substrate-1 (IRS-1) is an endogenous substrate for the insulin receptor tyrosine kinase, which plays a key role in insulin signaling. Recent studies have identified several polymorphisms in the human IRS-1 gene (Irs-1) that are increased in prevalence among type 2 diabetic patients. To determine whether variation in the Irs-1 contributes to genetic susceptibility to type 2 diabetes in Turkish people, PCR-RFLP and DNA sequencing method were utilized to analyze the coding region of Irs-1 in 70 subject and 116 control patients. Three missense mutations were detected (Gly972Arg, Ala512Pro, Ser892Gly). There was no significant association found with any of these variants and diabetes. The Gly972Arg mutation, however, was relatively more common in with 10/70 diabetic patients and 15/116 non-diabetic controls being heterozygous and 1/70 being and 0/116 non-diabetic controls being homozygous for this variant. As a conclusion, Ala512Pro, Ser892Gly mutations were rare and Met613Val, Ser1043Tyr and Cys1095Tyr mutations were not found in the populations studied. Gly972Arg is more common than other known mutations in our population but may not be a major determinant in genetic susceptibility to type 2 diabetes.