Relation of vitamin D and BsmI variant with temporomandibular diseases in the Turkish population.

Vitamin D (VD) levels and several variants in the vitamin D receptor (VDR) gene are associated with the occurrence of diseases of the bones and cartilage. The aim of this research was to study and compare the association of the BsmI variant in the VDR gene as well as VD levels in disc displacement with reduction (DDR) between patients and healthy controls. This was a case-control study, in which 104 patients of DDR and 102 healthy individuals were studied. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) was used to diagnose temporomandibular diseases. The VDR BsmI variant was investigated, after extraction of genomic DNA, by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and the VD level in serum was measured. The serum VD level was significantly different between the patient and the control group (mean (SD) 13.20 (11.02) ng/mL versus 18.44 (10.03) ng/mL, respectively) (p=0.008). Serum VD assessment revealed that serious vitamin D deficiency was more prevalent in the patients than the controls (50.96% versus 21.56%) (p=0.00001). Logistic regression analysis revealed that the bb genotype and b allele carriers of VDR BsmI variant were significantly associated with increased risk of DDR (p=0.022 and p=0.01, respectively). VDR BsmI BB genotype was higher in the control group than the patient group (p=0.045). Genotype distributions for BsmI variant in the controls and the patients were confirmed using the Hardy-Weinberg equilibrium equation. The BsmI variant of the VDR gene and VD deficiency play role in DDR aetiopathogenesis in a Turkish population. Vitamin D level and VDR BsmI variation may be effective in a possible genetic-based DC/TMD Axis III to be created in the future.

Analysis of common MDR1 (ABCB1) gene C1236T and C3435T polymorphisms in Turkish patients with familial Mediterranean fever.

The multidrug resistance (MDR1) gene encodes a P-glycoprotein that plays a key role in drug bioavailability and response to drugs in different human populations. More than 50 SNPs have been described for the MDR1 gene. Familial Mediterranean fever (FMF) is considered an autosomal recessive hereditary disease, associated with a single gene named the Mediterranean fever gene (MEFV). However, about one-third of FMF patients have only one mutated allele, suggesting that this disease is expressed as an autosomal dominant trait with partial penetration or an additional gene might be responsible for the disease. We made genotype and haplotype analyses of the MDR1 gene in 142 FMF patients and 130 unrelated Turkish subjects; two MDR-1 genetic markers (C1236T and C3435T) were analyzed by PCR-RFLP analysis. FMF patients had a significantly higher frequency of the 3435 CT genotype compared with the control group (59.9% in FMF patients versus 44.6% in controls; odds ratio [OR] = 1.85; 95% confidence interval [CI] = 1.14-3.00). Based on haplotype analysis, the T-C shift was significantly more frequent in controls (14.4% versus 7.1% in FMF patients). This haplotype could be protective for FMF disease (OR = 0.45; 95%CI = 0.25-0.84). The frequency of CC-CT (1236-3435) binary genotype was significantly higher in FMF patients (14.79% versus 4.61% in controls; OR = 3.59; 95%CI = 1.40-9.20).

Genotype and allele frequencies of MDR1 gene C1236T polymorphism in a Turkish population.

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.