Polymorphisms in Turkish population

Department of Molecular Biology and Genetics, and 2Molecular Biology and Biotechnology Research Center, Istanbul Technical University, Istanbul, Turkey. turanlie@itu.edu.tr

OBJECTIVES: To analyse the most common MEFV (Mediterranean fever gene) mutations and polymorphisms in an elderly population free of chronic inflammatory disease (n=164), and explore possible associations between hsCRP (high sensitive C-reactive protein) and RF (rheumatoid factor) levels with MEFV mutations and polymorphisms. METHODS: An elderly group free of chronic inflammatory disease was chosen among the outpatients of the division of geriatric medicine. Total genomic DNA was isolated from blood, and PCR-RFLP analysis was performed using established protocols. Sera were analyzed for hsCRP and RF levels. RESULTS: The frequencies for 694V (1.8%), 694I (1.8%), 680I (0.6%), 726A (2.1%) and 148Q (5%) alleles were found to be similar to Turkish historic controls, with a carrier frequency of 1/4. Further analyses with rheumatoid factor (RF) levels and mutations revealed a significant association between the presence of the E148Q polymorphism with increased RF levels (>15 mg/dl) (xi2= 7.358, p=0.007, OR=5.41 95% CI 1.41-20.64). CONCLUSIONS: Common MEFV mutations and polymorphisms were similarly represented among the elderly population compared to historic controls. On the other hand, a significant association was found between the presence of E148Q polymorphism and increased RF levels. This suggests that the previously noted increased RF levels in elderly populations may somehow be related to the now described association of RF with MEFV E148Q polymorphism.

Gazi University, Faculty of Medicine.

Hypoxia-inducible factor-1 (HIF-1), an important genetic component of angiogenesis, becomes stable as a response to tumor hypoxia and facilitates tumor survival. The polymorphisms of the HIF-1alpha gene may cause changes in the activity of the protein which serves as a transcription factor for many genes in tumorigenesis. In this study, we have investigated the relationship between seven HIF-1alpha polymorphisms [C>T substitution in intron 8 (rs10873142), T418I (rs41508050) in exon 10, P564P (rs41492849), L580L (rs34005929), P582S (rs11549465), A588T (rs11549467) in exon 12 and dinucleotide GT repeat in intron 13 (rs10645014)] among lung cancer patients in the Turkish population. Genomic DNA was isolated from 141 lung cancer cases and 156 controls and subjected to PCR for amplification. Genotyping was carried out with RFLP and DNA sequencing methods. There was no significant difference between lung cancer cases and controls in terms of the distribution of genotyping frequencies of seven HIF-1alpha polymorphisms (P>0.05). No significant relationship was found between the C>T substitution in intron 8 and P582S haplotypes and development of lung cancer. Also, no significant difference was observed between the genotypes and clinopathological characteristics of the cases. These findings showed that polymorphisms of the HIF-1alpha gene did not confer susceptibility to lung cancer.

Akdeniz University Teknocity, Kampus Antalya, Turkey.

Cytotoxic T lymphocyte-associated antigen-4 is a cell-surface molecule providing a negative signal for T cell activation. CTLA-4 gene polymorphisms are known to be related with genetic susceptibility to various autoimmune diseases, including systemic lupus erythematosus (SLE). However, the effects of this polymorphism on clinical features of SLE have not been defined. We analysed the CTLA-4 gene +49 A/G polymorphisms in patients with SLE by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and investigated the effect of polymorphisms on clinical outcomes. Blood was collected from 47 unrelated Turkish SLE patients, all fulfilling the American College of Rheumatology criteria for SLE, and 100 ethnically matched healthy volunteers. The AA genotype was a predominant genotype in the Turkish population and genotype frequencies of CTLA-4 AA were significantly higher in SLE patients (70%) than healthy controls (47%) (P = 0.015). There was a statistically significant difference in the AA genotype [odds ratio (OR): 2.66, confidence interval (CI) 95%: 1.27-5.56, P = 0.014] distribution among patients and controls. There was also an increase in A allele frequency in SLE and controls, but the difference was not statistically significant (81% vs. 70%, P = 0.068, OR = 1.8, CI 95%: 0.99-3.28). Interestingly, mean age and mean age of onset disease was higher in AA homozygote SLE patients compared to non-AA (39.2 +/- 11.5 vs. 31.6 +/- 10.6, P = 0.044; 32.38 vs. 24.31, P = 0.046, respectively). There was no association between genotype and the other clinical features of SLE. Our results suggested that CTLA-4 +49 AA genotype might be a risk factor for the development of SLE in Turkish population and G allele might be involved in early development of SLE. No association with clinical features was found for polymorphism of the promoter region in CTLA-4 +49.