Regulation of Shootin1 Gene Expression Involves NGF-induced Alternative Splicing during Neuronal Differentiation of PC12 Cells.

Shootin1 is a protein involved in neuronal polarization, and has been shown to be a key molecule for the positive/negative feedback loop for axon induction required during neuronal symmetry breaking. To better understand the molecular basis of shootin1 dynamics, we analysed the regulatory pathways and the expressional status of shootin1 gene during NGF-induced neuronal differentiation. We demonstrated that the isoform-1 and isoform-2 of shootin1 is differentially expressed during neuronal differentiation. By blocking individual downstream pathways of NGF signalling, we found that PI3K/Akt pathway plays a major role in the expression of shootin1 isoform-2. Western blot and RT-PCR results showed that the isoform-1 of shootin1 is constitutively expressed, while the isoform-2 is expressed in a manner that is strictly dependent on NGF-stimulation. Isoform-specific RT-PCR results demonstrated that the differential expression of the isoform-1 and isoform-2 of shootin1 is a consequence of alternative splicing of shootin1 pre-mRNA, in response to NGF-signalling. Collectively these findings provide the first information on the molecular mechanisms regulating the expression of shootin1 gene and represent the first example of NGF-induced alternative splicing process that has a regulatory role in neuritogenesis.

The Impact of Gene Polymorphisms on the Success of Anticholinergic Treatment in Children with Overactive Bladder.

AIM: To determine the impact of gene polymorphisms on detrusor contraction-relaxation harmony in children with lower urinary tract symptoms (LUTS). MATERIALS AND METHODS: Toilet trained children older than 5 years of age with LUTS and normal neurological examination underwent videourodynamic study. The control group was composed of age matched children with no voiding complaints. The study group who filled out the voiding dysfunction symptom score before and after the treatment received standard oxybutynin treatment and was reevaluated 1 year after treatment. Genomic DNA was isolated from all patients and subjected to PCR for amplification. Genotyping of ARGHEF10, ROCK2, ADRB3, and CYP3A4 was carried out with Polymerase Chain Reaction- Restriction Fragment Length Polymorphism (PCR-RFLP) method. RESULTS: 34 (45%) and 42 (55%) patients were enrolled in the study and control group, respectively. ARGEF10 GG, ADRB3 TC, and CYP3A4 AG genotype patients displayed insignificant difference between pre- and posttreatment voiding dysfunction symptom score and bladder volumes. CONCLUSIONS: The polymorphism of genes in the cholinergic pathway did not significantly differ clinical parameters. On the other hand, polymorphic patients in the adrenergic pathway seemed to suffer from clinical disappointment. For this reason, we think that the neglected adrenergic pathway could be a new therapeutic target for the treatment of anticholinergic resistant LUTS in children.

High-fructose corn syrup-induced hepatic dysfunction in rats: improving effect of resveratrol.

PURPOSE: The increased consumption of high-fructose corn syrup (HFCS) may contribute to the worldwide epidemic of fatty liver. In this study, we have investigated whether HFCS intake (20% beverages) influences lipid synthesis and accumulation in conjunction with insulin receptor substrate-1/2 (IRS-1; IRS-2), endothelial nitric oxide synthase (eNOS), sirtuin 1 (SIRT1) and inducible NOS (iNOS) expressions in liver of rats. Resveratrol was tested for its potential efficacy on changes induced by HFCS. METHODS: Animals were randomly divided into four groups as control, resveratrol, HFCS and resveratrol plus HFCS (resveratrol + HFCS). HFCS was given as 20% solutions in drinking water. Feeding of all rats was maintained by a standard diet that enriched with or without resveratrol for 12 weeks. RESULTS: Dietary HFCS increased triglyceride content and caused mild microvesicular steatosis in association with up-regulation of fatty acid synthase and sterol regulatory element binding protein (SREBP)-1c in liver of rats. Moreover, HFCS feeding impaired hepatic expression levels of IRS-1, eNOS and SIRT1 mRNA/proteins, but did not change iNOS level. Resveratrol promoted IRS, eNOS and SIRT1, whereas suppressed SREBP-1c expression in rats fed with HFCS. CONCLUSIONS: Resveratrol supplementation considerably restored hepatic changes induced by HFCS. The improvement of hepatic insulin signaling and activation of SIRT1 by resveratrol may be associated with decreased triglyceride content and expression levels of the lipogenic genes of the liver.

Quantitative measurement of m-RNA levels to assess expression of cyclooxygenase-II, inducible nitric oxide synthase and 12-lipoxygenase genes in middle ear cholesteatoma.

To assess expression of three main inflammatory genes, COX-II, ALOX-12 and i-NOS, quantitatively at transcriptional level in cholesteatoma matrix tissue. Ten patients who have chronic otitis media with primary acquired cholesteatoma were included in this study. Tissue samples obtained from cholesteatoma matrix and external ear canal skin (control tissue). Expression of the targeted genes (COX-II, i-NOS and LOX-12) was assessed using real-time quantitative polymerase chain reaction (RT-PCR) technique. The amount of COX2 mRNA was significantly higher in cholesteatoma matrix at transcriptional level (p = 0.038). There was no statistically significant difference regarding expression of iNOS and LOX12 mRNA levels (p > 0.05). There is a significant overexpression of the mRNA of COX-II in cholesteatoma matrix, which indicates a difference between the normal skin and cholesteatoma matrix at molecular level. COX-II gene overexpression seems to be associated with pathogenesis of cholesteatoma. This molecular change is similar to the molecular abnormalities observed in some benign and malignant neoplasms. Invasive and locally destructive nature of cholesteatoma may be due to COX-II overexpression. Absence of an increase in the gene expressions of i-NOS and LOX-12 in cholesteatoma matrix suggests that these mediators may not be related with the pathogenesis and evolution of cholesteatoma.

Non-steroidal anti-inflammatory drug-activated gene-1 expression levels in nasal polyposis.

OBJECTIVES: This study aims to investigate the possible role of non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) in nasal polyp development. PATIENTS AND METHODS: Twenty-one patients (15 males, 6 females; mean age 44.3 years; range 16 to 65 years) who underwent endoscopic sinus surgery for nasal polyposis (NP) were included in the study. Inferior turbinate mucosa samples were taken in addition to the polyp tissue which was already removed during routine procedure. The NAG-1 gene messenger ribonucleic acid (mRNA) expression levels of the polyp tissue and healthy turbinate mucosa were examined by real-time polymerase chain reaction (PCR). Patients were divided into two groups based on the presence or absence of comorbid asthma. RESULTS: The NAG-1 gene expression of the polyp tissue was 1,089 fold higher, compared to the healthy nasal mucosa (p=0.757). The NAG-1 mRNA levels were 2.13 times decreased in the patients with comorbid asthma (p=0.275). There was no statistically significant difference between the groups. CONCLUSION: With the findings of this study NAG-1 gene may play a role in nasal polyp development in the presence of comorbid asthma.

Effects of ketamine, propofol, and ketofol on proinflammatory cytokines and markers of oxidative stress in a rat model of endotoxemia-induced acute lung injury.

Intravenous lipopolysaccharide (LPS) leads to acute lung injury (ALI) in rats. The purpose of this study was to examine the anti-inflammatory and antioxidant efficacy of ketamine, propofol, and ketofol in a rat model of ALI. We induced ALI in rats via intravenous injection of LPS (15 mg kg(-1)). The animals were randomly separated into five groups: control, LPS only, LPS + ketamine (10 mg·kg(-1)·h(-1)), LPS + propofol (10 mg·kg(-1)·h(-1)), LPS + ketofol (5 mg·kg(-1)·h(-1) ketamine + 5 mg·kg(-1)·h(-1) propofol). LPS resulted in an increase in the release of pro-inflammatory cytokines, mRNA expression related with inflammation, production of nitric oxide, and lipid peroxidation. Ketamine prevented the increase in markers of oxidative stress and inflammation mediators, both in plasma and lung tissue. Propofol decreased the levels of cytokines in plasma and lung tissue, whereas it had no effect on the IL-1-beta level in lung tissue. Ketamine downregulated mediators of lung tissue inflammation and reduced the level of circulating cytokines and protected lung tissue against lipid peroxidation. Ketofol decreased the level of TNF-α and IL-1ß in plasma, as well as expression of cyclooxygenase-2 mRNA and the nitrate/nitrite level in lung tissue. The results of this investigation support the hypothesis that ketamine may be effective in preventing ALI.

4,5-dianilinophtalimide protects neuroendocrine cells against serum deprivation-induced stress and apoptosis.

OBJECTIVE: The aim of this study was to reveal the effects of 4,5-dianilinophthalimide (DAPH), which inhibits amyloid ß fibrillization, against serum deprivation (SD)-induced apoptosis and the possible mechanisms in differentiated PC12 neuron cells. METHODS: Firstly, we evaluated whether DAPH protects cell viability exposed to SD by MTT assay. Next, we examined the changes of phospho-p38 MAPK (Thr180/Tyr182), phospho-HSP27 (Ser82), phospho-c-JUN (Ser73) and cleaved-CASP3 (Asp175) profiles by immunoblotting, in PC12 cells exposed to SD. Intracellular reactive oxygen species (ROS) level was also measured. RESULTS: SD induced apoptosis accompanied by up-regulation of phospho-p38 MAPK (Thr180/Tyr182), phospho-HSP27 (Ser82), phospho-c-JUN (Ser73), cleaved-CASP3 (Asp175) and intracellular ROS content. Co-treatment with non-toxic doses of DAPH prevented apoptosis by the attenuation of activated proteins and reduction of ROS level. These results suggest that serum deprivation-induced apoptosis inhibited by DAPH administration. CONCLUSION: We have provided for the first evidence that DAPH has a neuroprotective effect on SD-caused stress, probably via contributing the re-establishment of redox homeostasis.

Expression of cyclooxygenase-2, 12-lipoxygenase, and inducible nitric oxide synthase in head and neck squamous cell carcinoma.

AIM: The objective of this study was to investigate whether cyclooxygenase-2 (COX-2), 12-lipoxygenase (12-LOX), and inducible nitric oxide synthase (iNOS) have a role in carcinogenesis of head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS: Twenty-two patients with HNSCC were included in the study. Cancer tissues and adjacent normal mucosa were obtained from each patient. Real-time PCR was used to assess the expression of COX-2, 12-LOX, and iNOS. RESULTS: COX-2 and 12-LOX mRNA expressions are significantly increased in HNSCC compared with adjacent normal mucosa. Expression of iNOS was not significantly elevated in overall head and neck cancer tissues compared with normal mucosa. However, iNOS expression was found to be significantly elevated in patients with laryngeal cancer. CONCLUSION: These data suggest that COX-2 and 12-LOX may play a role in carcinogenesis of head and neck cancer. iNOS as well as COX-2 and 12-LOX may play a role in carcinogenesis of laryngeal cancer.

Effects of the adverse life events and Disrupted in Schizophrenia-1 (DISC1) gene polymorphisms on acute symptoms of schizophrenia.

The aim of this study was to evaluate the effects of traumatic childhood events and recent adverse life events, as well as the Disrupted in Schizophrenia-1 (DISC1) gene polymorphisms on types of last acute symptoms of patients with schizophrenia. Hundred patients with schizophrenia were given the Childhood Trauma Questionnaire, the Social Readjustment Rating Scale, Scale for Assessment of Positive Symptoms (SAPS), Scale for Assessment of Negative Symptoms (SANS), Brief Psychiatric Rating Scale (BPRS), and Calgary Depression Scale for Schizophrenia (CDSS). The patients' and healthy controls' DISC1 gene was evaluated for the -274G>C, c.791G>A, and c.2110A>T polymorphisms. There was no statistically significant difference with regard to the DISC1 gene polymorphisms between patient and healthy control groups. No significant relationship was found between the -274G>C, c.791G>A, and c.2110A>T haplotypes and development of different acute symptoms of schizophrenia. Having a recent stressful life event significantly affected SAPS (95% confidence interval [CI]=-67.547, -21.473; p=0.00) and BPRS-1 scores (95% CI=-51.405, -6.885; p=0.01), whereas emotional abuse at childhood significantly affected SANS scores (95% CI=-37.300, -10.401; p=0.00). This study shows that features of acute symptoms in schizophrenia are not influenced by the polymorphisms on the DISC1 gene, but are influenced by recent adverse life events and emotional abuse at childhood.

[The role of COX-2, ALOX12 and iNOS genes in nasal polyposis]. / COX-2, ALOX12 ve iNOS genlerinin nazal polipozisteki rolü

OBJECTIVES: The aim of this study was to investigate whether cyclooxygenase-2 (COX-2), arachidonate 12-lipoxygenase (ALOX12) and inducible nitric oxide synthase (iNOS) which are well-known mediators in inflammatory process play a role in nasal polyposis (NP) and to show their roles in initiation and progression of inflammation. PATIENTS AND METHODS: We investigated the expression levels of COX-2, ALOX12 and iNOS genes by real-time polymerase chain reaction (PCR) method in NP tissues obtained from 10 patients (4 females, 6 males; mean age ?? years; range 21 to 54 years). RESULTS: The mRNA levels of COX-2 expression observed in NP was found to be relatively increased, compared to the control tissue (p>0.05). The ALOX12 levels were relatively decreased (p>0.05), while the expression level of iNOS mRNA was significantly higher in NP tissue (p<0.05). CONCLUSION: These data suggest that nitric oxide (NO), a gene product of iNOS, may play a physiological role in the upper airways and also NO is associated with inflammatory processes in the airways.

Synthesis and biological evaluation of the salicylamide and salicylic acid derivatives as anti-estrogen agents.

Alkylphenols have xenoestrogenic activity, which mimic the action of physiological estrogens and these mimicking activities are mainly mediated by nongenomic pathway. Nongenomic pathway plays a pivotal role in breast, endometrial and ovarian cancers' growth and development. In this study, various alkylphenol derivatives were prepared and screened for their anti-uterotrophic and uterotrophic activity. Among these compounds, 2-hydroxy-5-nonanoylbenzamide (compound 1b) showed 93.99% inhibitory activity in the anti-uterotrophic test performed, and was found inactive in the uterotrophic activity test. Moreover, all test compounds were examined for the effect on uterine histopathological changes, and plasma 17ß-estradiol (E2) level. Compound 1b was also tested for in vitro anti-cancer activity against ER+, human breast cancer cell line MCF-7, and it reduced cell viability to 74.01% at 50 nM concentration.

Investigation of ocular neovascularization-related genes and oxidative stress in diabetic rat eye tissues after resveratrol treatment.

Changes in vascular endothelial growth factor (VEGF), angiotensin-converting enzyme (ACE), matrix metalloproteinase (MMP)-9, and endothelial nitric oxide synthase (eNOS) mRNA expression profiles and oxidative stress in the eye tissue microenviroment may have important roles in ocular neovascularization and permeability in proliferative diabetic retinopathy. The present study investigated the effects of resveratrol (RSV) treatment on the mRNA expression profile of VEGF, ACE, MMP-9, and eNOS, which are associated with vascular neovascularization, and glutathione, protein carbonyl, and nitrite-nitrate levels, which are markers of oxidative stress in eyes of diabetic rats. Twenty-four Wistar albino male rats were divided into four groups. After diabetes induction with streptozotocin (10 mg/kg/day) RSV was administered to the RSV and diabetes mellitus (DM) + RSV groups for 4 weeks. The mRNA levels were measured by quantitative real-time polymerase chain reaction assay, and biochemical estimations were determined with spectrophotometric assays in eye homogenates. The mRNA expression levels of VEGF, ACE, and MMP-9 were increased in the DM group compared with the control group, and RSV treatment decreased their mRNA levels. Expression of eNOS mRNA was increased in the RSV and DM groups and decreased in the DM + RSV group. Nitrite-nitrate levels and protein carbonyl content were increased and glutathione levels were decreased in the DM group compared with controls. Consequently, these data suggest that RSV suppressed the expression of eNOS, which is actively involved in the inflammation and healing process in chronic diabetes. Although oxidative stress was increased in eye tissue from diabetic rats, mRNA levels of VEGF, MMP-9, and ACE genes associated with vascular remodeling did not change in diabetic eyes.

Association of GJB2 gene mutation with cochlear implant performance in genetic non-syndromic hearing loss.

OBJECTIVE: To analyze the association of GJB2 gene mutations with cochlear implant performance in children. METHODS: Sixty-five consecutive children who underwent cochlear implantation due to congenital profound senseurineural hearing between 2006 and 2008 were included in the study. In children, GJB2 gene mutation analysis was performed. Their auditory performance was assessed using MAIS, MUSS and LittlEARS tests. RESULTS: Twenty-two of sixty-five patients GJB2 mutations, and 35delG was the most frequent mutation. No significant difference was found between the auditory performance of mutation positive and negative children after one year follow up (p>0.05). CONCLUSION: GJB2 gene mutations do not impact on the outcome of cochlear implantation.

Inflammation and oxidative stress in testicular torsion: do they deserve intensive treatment to save both guilty and innocent testes?

OBJECTIVES: To investigate at the molecular level, whether the combined use of an antioxidant (L-carnitine) and a selective cyclooxygenase-2 (COX-2) inhibitor (meloxicam) is effective in the treatment of cellular damage caused by testicular torsion. METHODS: A total of 30 male Wistar rats were randomly divided into 5 groups. The control group underwent a sham operation, and the second group underwent torsion/detorsion for 90 minutes. Groups 3 and 4 received L-carnitine (500 mg/kg/d) and meloxicam (3 mg/kg/d), respectively. Group 5 also received these 2 agents, in addition to the same torsion/detorsion procedure. Bilateral orchiectomy was performed 96 hours after the operation in all groups. cDNA was synthesized after isolation of total RNA from the tissues. The relative expression of interleukin (IL)-1a, COX-2, and ß-actin genes was measured by real-time polymerase chain reaction. RESULTS: The COX-2 and IL-1a mRNA levels had significantly decreased in groups 3, 4, and 5 compared with group 2 (P<.05). COX-2 and IL-1a mRNA levels were significantly great in the torsion/detorsion group (P=.007). The COX-2 and IL-1a mRNA levels significantly decreased in the torsion/detorsion testis after maximal treatment (P<.001). CONCLUSIONS: Meloxicam seems to exert its inhibitory effect on the expression of specific genes of inflammation, as well as the combination therapy. Because the effects of these inflammatory genes are still evident 4 days after detorsion, combination therapy using these agents could be administered until late postoperative period to prevent the initiation of autoimmune activity against sperm cells and protect the innocent contralateral testis from the insult of antisperm antibodies.

PON1 55 and 192 gene polymorphisms in type 2 diabetes mellitus patients in a Turkish population.

Diabetes mellitus is a multifactorial metabolic disease, caused by the complete or relative absence of insulin hormone, which results in the deterioration of carbohydrate, protein, and lipid metabolism. The PON1 55 and 192 polymorphisms have been reported to be associated with type 2 diabetes and its complications. In this study, the involvement of the PON1 55 and 192 polymorphisms and paraoxonase enzyme activity in diabetic complications was assessed. The MM and QQ genotypes were the most frequent in complications of type 2 diabetes in both of the polymorphisms. PON enzyme activity was lower in the type 2 diabetes group with respect to the control group. Regarding both genotypes and enzyme activity, correlations were found between the PON1 55 and 192 genotypes and diabetic complications. This study thus helps to outline a genotype-phenotype relation for the PON1 gene in a Turkish population.

Significance of serotonin transporter gene polymorphism in tinnitus.

OBJECTIVES: To assess the role of serotonin transporter gene (SLC6A4) polymorphism in tinnitus. MATERIALS AND METHODS: Fifty-four consecutive patients experiencing subjective tinnitus and 174 healthy controls were allocated for the study. Psychoacoustic parameters of tinnitus were measured. Beck Depression Inventory was used to assess the depression level of the patients. Tinnitus Handicap Inventory was used to assess the severity of tinnitus. A visual analog scale was designed to measure the impact of tinnitus on quality of life of the patients. The 44-bp insertion-deletion in the promoter region (5-HTTLPR) and 17-bp variable number tandem repeats in the second intron of the serotonin transporter gene were assessed. RESULTS: No difference was found between the genotypes and allele frequencies of the patients and controls regarding variable number tandem repeats and 5-HTTLPR polymorphisms (p > 0.05). There was no association between the psychoacoustic parameters of tinnitus and SLC6A4 polymorphism (p > 0.05). There was a significant association between the 5-HTTLPR polymorphism and scores from the visual analog scale of the patients (p < 0.05). CONCLUSION: Generation of tinnitus signal is not associated with SLC6A4 polymorphism and possibly with serotonergic mechanisms. However, the "ll" genotype variant of the SLC6A4 polymorphic promoter region seems associated with the limbic and autonomic nervous system symptoms of the patients with tinnitus. Therefore, serotonergic mechanisms may help explain the neurophysiological model of tinnitus, and serotonin replacement or serotonin reuptake inhibitors may increase the success rate of tinnitus treatment modalities based on the neurophysiologic model of tinnitus.

Two novel missense mutations in the connexin 26 gene in Turkish patients with nonsyndromic hearing loss.

Most nonsyndromic hearing losses are caused by mutations in the GJB2 gene, and studies have revealed that the forms and frequencies of these mutations are largely dependent on ethnic origin. In the present study, we aimed to characterize the mutation profiles of 151 patients with hearing loss in Turkey. The entire coding region of the GJB2 was directly sequenced in all patients. We found 35 (23.2%) individuals carrying GJB2 mutations. Seven different mutations were identified, five of which were previously known (35delG, delE120, R184P, M163V, L90P), the remaining two being novel variants (M34V, L205V). The most common mutation was 35delG followed by delE120. The 35delG mutation was homozygous in 22 cases (14.5%) and heterozygous in 4 cases (2.6%). Compound heterozygosity for 35delG was also observed. The delE120 mutation was found in three patients in homozygous form. A homozygous L90P and heterozygous mutations M163V and M34V were found in single cases.

Genetic polymorphisms of FSHR, CYP17, CYP1A1, CAPN10, INSR, SERPINE1 genes in adolescent girls with polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS), whose genetic basis is not completely well understood, is the most common endocrine disorder in women and it typically develops during adolescence. The aim of this study is to investigate the possible association between single nucleotide polymorphisms (SNPs) of FSHR, CYP17, CYP1A1, CAPN10, INSR, SERPINE1 genes and PCOS in adolescent girls. METHODS: DNA samples from forty-four adolescent girls with PCOS and 50 healthy controls were analyzed by PCR-RFLP and direct DNA sequencing to determine the genotypic frequency of 17 different polymorphic loci on the FSHR (A307T, N680S), CYP17 (-34 T/C), CYP1A1 (T6235C), CAPN10 (44, 43, 19, 63), INSR (exon 17 C/T), SERPINE1 (4G/5G) genes. Genotyping of exon 12 (six polymorphisms) and intron 12 (one polymorphism) of INSR gene by direct DNA sequencing was performed for the first time in this study. RESULTS: No significant differences were observed in the genotype and allele distributions of above mentioned polymorphisms between cases and control groups. CONCLUSION: Our data does not support an association between SNPs of FSHR, CYP17, CYP1A1, CAPN10, INSR, SERPINE1 genes and susceptibility to PCOS or related traits in Turkish adolescent girls.

Melanocortin-4 receptor gene polymorphisms in obese patients.

Obesity is a complex disease caused by both genetics and environmental factors. Melanocortin-4 receptor (MC4R) (MIM 155541) gene polymorphisms were reported to be the cause of monogenic obesity in humans. We studied three polymorphisms (Val50Met, Val103Ile, and Ser58Cys) and a mutation (Asn274Ser) of the MC4R gene in 203 obese patients and in 110 healthy subjects in the Turkish population. A high incidence of Val103Ile and Val50Met polymorphisms as well as the Asn274Ser mutation was found in the obese patients, whereas no significant correlation was found regarding the Ser58Cys polymorphism. We conclude that there is a concordance between the polymorphisms (Val103Ile, Val50Met, Ser58Cys) that were first studied in the Turkish population with obesity.

GJB2 and mitochondrial A1555G gene mutations in nonsyndromic profound hearing loss and carrier frequencies in healthy individuals.

This study aimed to assess mutations in GJB2 gene (connexin 26), as well as A1555G mitochondrial mutation in both the patients with profound genetic nonsyndromic hearing loss and healthy controls. Ninety-five patients with profound hearing loss (>90 dB) and 67 healthy controls were included. All patients had genetic nonsyndromic hearing loss. Molecular analyses were performed for connexin 26 (35delG, M34T, L90P, R184P, delE120, 167delT, 235delC and IVS1+1 A-->G) mutations, and for mitochondrial A1555G mutation. Twenty-two connexin 26 mutations were found in 14.7% of the patients, which were 35delG, R184P, del120E and IVS1+1 A-->G. Mitochondrial A1555G mutation was not encountered. The most common GJB2 gene mutation was 35delG, which was followed by del120E, IVS1+1 A-->G and R184P, and 14.3% of the patients segregated with DFNB1. In consanguineous marriages, the most common mutation was 35delG. The carrier frequency for 35delG mutation was 1.4% in the controls. 35delG and del120E populations, seems the most common connexin 26 mutations that cause genetic nonsyndromic hearing loss in this country. Nonsyndromic hearing loss mostly shows DFNB1 form of segregation.