Transcription factor 4 gene rs9960767 polymorphism in bipolar disorder.

The transcription factor 4 (TCF4) gene encodes a helix-loop-helix transcription factor protein, which initiates neuronal differentiation and is primarily expressed during nervous system development. The aim of the present study is to investigate the association of the TCF4 rs9960767 polymorphism and bipolar disorder, which is highly heritable. DNA isolation was performed on 95 patients with bipolar disorder and 108 healthy control subjects to examine the TCF4 rs9960767 polymorphism. Genotypic and allelic frequencies were determined using the polymerase chain reaction-restriction fragment length polymorphism method designed in our laboratory. Statistical analysis was performed using χ2 test within the 95% confidence interval. Odds ratios were calculated and Hardy-Weinberg equilibrium (HWE) was verified for all control subjects and patients. The A allele frequency was 95.8% in the patients and 94.4% in the control subjects, and 4.2% in the patients and 5.6% in the control subjects for the C allele. The genotype frequencies of the TCF4 gene rs9960767 variant were as follows: AA, 91.6% and AC, 8.4% in patients with bipolar (CC genotype was not observed in cases); AA, 89.8%; AC, 9.3% and CC, 0.9% in the control subjects. No statistically significant difference was identified between the patients and control subjects (χ2=0.937; P=0.626). In addition, gender specific analysis was performed, although no significant association was found according to the gender distrubition. All patients and control subjects were in HWE (P>0.05). Statistical analysis of the data indicates that the TCF4 gene rs9960767 polymorphism is not an independent risk factor for bipolar disorder in the overall population or in terms of gender; however, an increased population size would improve the statistical power. Furthermore, additional gene variants that are specifically involved in neuronal development may be analyzed for revealing the complex genetic architecture of bipolar disorder. An improved approach would be better to evaluate the TCF4 gene in a pathway specific manner due to its role as a transcription factor.

Association of rs62063857 variant of the saitohin gene with Parkinson's disease.

Saitohin gene found within the tau gene is thought to play a role in the pathogenesis of neurodegenerative diseases. The rs62063857 polymorphism originally found in the saitohin gene seems to be the responsible SNP in this event. This polymorphism is studied mostly in patients with Alzheimer's disease. Data on Parkinson's disease are scarce. Therefore, we examined the rs62063857 polymorphism in 583 Parkinson's disease patients (347 male and 236 female) and 396 healthy controls (238 male and 158 female) by a polymerase chain reaction and restriction fragment length polymorphism method to see whether it was associated with Parkinson's disease from the City of Istanbul, Turkey. The G allele frequency was 22 % in overall controls and 16 % in Parkinson's disease patients. In this study, the saitohin rs62063857 polymorphism was associated with Parkinson's disease (χ2 = 16.765; P = 0.000). Individuals with the AA genotype showed 1.7-fold increased risk for Parkinson's disease (χ2 = 16.680; P = 0.000), whereas individuals with the AG genotype revealed protection against Parkinson's disease (χ2 = 14.554; P = 0.000). After the stratification analysis according to gender, both male and female PD patients showed association with the alleles and genotypes of the rs62063857 polymorphism of the saitohin gene (χ2 = 9.476, P = 0.009; χ2 = 7.593, P = 0.022, respectively). When the Parkinson's patients were divided into two groups with regard to onset of the disease, both groups showed association with the disease. The Parkinson's patients with disease onset below 65 years of age showed 1.8-fold increased risk for the disease. The Parkinson's patients with disease onset over 65 showed more robust association with a 2.051-fold increased risk for the disease. Consequently, the rs62063857 polymorphism of the saitohin gene is a genetic risk factor for Parkinson's disease. Hence, this polymorphism may play a role in the etiology of Parkinson's disease.

Genetic variants in the PNPLA3 gene are associated with nonalcoholic steatohepatitis.

In this study, we report the association of the rs738407, rs738409, and rs2896019 variants of the patatin-like phospholipase domain-containing protein 3 (PNPLA3) (adiponutrin) gene with nonalcoholic steatohepatitis (NASH) (χ(2)=14.528, p=0.001; χ(2)=18.882, p=0.000; χ(2)=7.449, p=0.024, respectively) in 80 patients with NASH and 303 healthy controls. We genotyped the subjects using three polymerase chain reaction-restriction fragment length polymorphism methods developed in our laboratory. Our findings confirm the findings of the recent case-control and genome-wide association studies carried out in different populations around the world. Thus, the three variants in PNPLA3 gene may be a genetic risk factor for NASH.

Association of nicotinamide-N-methyltransferase (NNMT) gene rs694539 variant with bipolar disorder.

Here we report the association of the rs694539 variant of nicotinamide-N-methyltransferase gene with bipolar disorder in a case-control study of 95 bipolar disorder patients and 201 healthy controls (χ(2)=13.382, P=0.001). With the polymerase chain reaction restriction fragment length polymorphism method we developed we were able to show the association for the first time. This new finding may provide evidence to understand the mechanism of the disease.

Association of nicotinamide-N-methyltransferase gene rs694539 variant with patients with nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal hepatic steatosis in the absence of a history of alcohol use and with a prevalence of 15%-45% in developed nations. Nonalcoholic steatohepatitis (NASH) is an advanced stage of NAFLD with a pronounced major inflammatory component. The aim of this study was to investigate the possible role of nicotinamide-N-methyltransferase (NNMT) gene rs694539 variant in the development of NASH. Therefore, we analyzed 80 NASH patients and 183 healthy controls using a polymerase chain reaction-restriction fragment length polymorphism method developed in our laboratory. The NNMT rs694539 variant was found to be significantly associated with NASH (χ(2)=9.349, p=0.009). The individuals with the GG genotype had protection against NASH (χ(2)=3.793, p=0.051, odds ratio [OR]=0.580, 95% confidence interval [CI]=0.334-1.006), whereas the individuals with the AA genotype showed statistically significant increased risk for NASH (χ(2)=7.748, p=0.005, OR=7.338, 95% CI=1.448-37.190). Moreover, the G allele was protective against NASH (χ(2)=7.748, p=0.005, OR=0.136, and 95% CI=0.027-0.691). On the other hand, the A allele was a risk factor for NASH (χ(2)=3.793, p=0.051, OR=1.725, and 95% CI=0.994-2.996). Consequently, the rs694539 variant of NNMT gene is a genetic risk factor for developing NASH.

ZNF804A rs1344706 variant and schizophrenia in a Romanian population from Cluj Napoca.

The ZNF804A rs1344706 variant was the first risk factor to be identified through genome-wide association studies and follow-up studies with meta-analysis for schizophrenia as well as bipolar disorders; we investigated 231 schizophrenia and 222 controls to see whether this particular variant was associated with schizophrenia in a Romanian population from Cluj Napoca. Clearly, there was no association between the ZNF804A rs1344706 variant and schizophrenia. Our study provides evidence for those that found no association with schizophrenia. A surprising result of our study was that the T allele frequency is the highest, thus far among the ethnic groups studied. We used a PCR-RFLP method that had been recently developed in our laboratory to the genotype ZNF804A rs1344706 variant. In conclusion, the ZNF804A rs1344706 variant was not associated with schizophrenia in the Romanian population from Cluj Napoca (χ(2)=0.734, p=0.693).

Gender-specific association of methylenetetrahydrofolate reductase gene polymorphisms with sporadic amyotrophic lateral sclerosis.

Studies have revealed that elevated homocysteine levels can cause damage to motor neurons through multiple neurotoxic mechanisms, thus leading to the pathogenesis of amyotrophic lateral sclerosis (ALS). One way by which homocysteine levels are increased in the body is the consequence of methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms. Therefore, to address this question, we studied the MTHFR C677T and A1298C polymorphisms in 437 sporadic ALS (SALS) and 439 healthy controls to learn whether they were associated with SALS. The overall SALS were not associated with MTHFR C677T and A1298C polymorphisms (χ(2)=1.378; p=0.502; χ(2)=1.304; p=0.521, respectively). However, when we stratified results in terms of gender, we found that the MTHFR C677T polymorphism (χ(2)=6.376; p=0.041), T677T genotype (χ(2)=5.508; p=0.019; odds ratio [OR]=2.561; 95% confidence interval [CI]=1.142-5.744), C677C/A1298A (χ(2)=5.216; p=0.022; OR=0.424, 95% CI=0.199-0.900), and T677T/A1298A (χ(2)=6.639; p=0.010; OR=2.900; 95% CI=1.252-6.717) compound genotypes were associated with SALS in female patients only. Moreover, stratification of SALS according to the onset of disease indicated that there was no association between MTHFR C677T (χ(2)=1.565; p=0.457; A1298C χ(2)=3.461; p=0.177) polymorphisms and overall spinal onset SALS. Further stratification analysis according to gender revealed that there was a remarkable association between MTHFR C677T (χ(2)=9.728, p=0.008), T677T genotype (χ(2)=7.820; p=0.005; OR=3.126; 95% CI=1.361-7.178) and T allele (χ(2)=5.000; p=0.025; OR=1.711; 95% CI=1.067-2.745), and T677T/A1298A compound genotype (χ(2)=9.108; p=0.003; OR=3.540; 95% CI=1.494-8.387) and spinal onset female SALS only. Likewise, there was also association between MTHFR A1298C polymorphism (χ(2)=5.946; p=0.051) and the C1298C genotype (χ(2)=5.282; p=0.022; OR=2.524; 95% CI=1.125-5.658), and the C677T/C1298C compound genotype (χ(2)=7.155; p=0.007; OR=1.045; 95% CI=0.983-1.112) and bulbar onset SALS only in women. In conclusion, the evidence we provide here clearly shows that MTHFR C677T and A1298C polymorphisms are genetic risk factors for SALS in women in a gender-specific manner whether they are of spinal or bulbar onset.

A polymerase chain reaction-restriction fragment length polymorphism method for screening ZNF804A gene polymorphism (rs1344706) in patients with schizophrenia: a significant association.

The original ZNF804A rs1344706 risk variant was identified through genome-wide association studies as a risk factor for schizophrenia. Follow-up studies involving meta-analysis have confirmed that rs1344706 is a risk factor for schizophrenia as well as bipolar disorders. We describe here a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to genotype ZNF804A rs1344706 variant in patients with schizophrenia. We generated a 220 bp fragment through PCR and subsequently cleaved it by the restriction endonuclease BsaBI, creating two fragments of 114 and 106 bp. Upon change in the nucleotide from T to G, the 106 bp fragment is further cleaved by BsaBI, thus creating two fragments of 87 and 19 bp. As a result, when the 220 bp fragment is cleaved by BsaBI restriction endonuclease, the TT genotype yields two fragments of 114 and 106 bp, and TG genotype four fragments of 114, 106, 87, and 19 bp, and the GG genotype three fragments of 114, 87, and 19 bp. Thus, this is a simple, fast, and cost-effective method to genotype the ZNF804A rs1344706 risk variant. Using this method, we were able to replicate an association between ZNF804A rs1344706 variant and schizophrenia in a Turkish population. Stratification analysis of the population according to the gender showed an association that was statistically significant among overall schizophrenia and male schizophrenia and the risk T allele and TT genotype of the ZNF804A gene.

TP53 Arg72Pro polymorphism in Turkish patients with sporadic amyotrophic lateral sclerosis.

Recently, Eve et al. (2007) reported that the expression of TP53 (NM_000546) was increased by 2.1-fold in whole spinal cord and 2.7-fold in the ventral horn of amyotrophic lateral sclerosis (ALS) patients. Based on this particular observation, we decided to evaluate whether the TP53 Arg72Pro polymorphism (rs1042522) (C215G) was implicated in the etiopathology of sporadic amyotrophic lateral sclerosis (SALS). Therefore, we genotyped 394 Turkish SALS patients and 439 matched healthy controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We did not find any association between overall SALS patients with the TP53 Arg72Pro polymorphism and controls (χ(2) = 2.674; p = 0.263). Consequently the TP53 Arg72Pro polymorphism was not associated with SALS.