Localized Provoked Vulvodynia: Association With Nerve Growth Factor and Transient Receptor Potential Vanilloid Type 1 Genes Polymorphisms.

OBJECTIVE: The aim of the study was to study the associations between localized provoked vulvodynia (LPV) and several single-nucleotide polymorphisms (SNPs) in the transient receptor potential vanilloid type 1 (TRPV1), nerve growth factor (NGF), and the heparanase (HPSE) genes. MATERIALS AND METHODS: Prevalence of SNPs among 65 women with moderate or severe primary LPV (initial symptoms occur with first provoking physical contact) and 126 healthy, ethnically matched controls was analyzed in an observational case-control study. Each participant answered a questionnaire addressing familial LPV occurrence and comorbid pain conditions. RESULTS: Familial occurrences of LPV, temporomandibular joint (TMJ) symptoms, recurrent vaginitis, and irritable bowel syndrome were significantly higher among LPV women than healthy controls. Genotyping analyses revealed a novel, statistically significant high prevalence of polymorphism c.945G>C (rs222747) of TRPV1 and a SNP in the promoter region of NGF (rs11102930) in LPV women compared with controls. A logistic regression model for rs222747 and rs11102930 frequent alleles indicates significant LPV association within the entire study group and Ashkenazi Jewish women, respectively. Comparison of pain conditions with frequent alleles showed the rs222747 "CC" genotype of TRPV1 associated with women with TMJ, recurrent vaginitis, and LPV. CONCLUSIONS: Our results suggest novel genetic susceptibility to primary LPV associated with specific alleles in genes TRPV1 and NGF and propose the rs222747 "C" allele of TRPV1 as a common genetic predisposition for other pain syndromes.

Catechol-O-methyltransferase gene polymorphism and vulvar pain in women with vulvodynia.

BACKGROUND: The underlying causes of vulvar pain in women with vulvodynia remain poorly understood. Catechol-O-methyltransferase, an enzyme that metabolizes catecholamines, is a neuromodulator that is involved with perception and sensitivity to pain. The catechol-O-methyltransferase gene is polymorphic, and a single nucleotide polymorphism is associated with low activity and heightened pain sensitivity. The variant allele that encodes this polymorphism commonly is called the "L allele" because of its low enzyme activity as opposed to the normal H (high activity) allele. OBJECTIVE: The methionine-containing catechol-O-methyltransferase protein coded by the L allele results in elevated catecholamine levels, reduced inactivation of the dopaminergic and adrenergic systems, and increased sensitivity to pain. This polymorphism not only may decrease the pain threshold in response to acute pain but also may facilitate the development of chronic pain. Therefore, the objective of our study was to assess whether a variation in the catechol-O-methyltransferase genotype is involved in increased pain sensitivity in women with vulvodynia. STUDY DESIGN: We conducted a prospective cohort study. METHODS: Buccal swabs were collected from 167 white women with vulvodynia and 107 control subjects; the DNA was tested for a single nucleotide polymorphism at position 158 (rs4680) in the catechol-O-methyltransferase gene. RESULTS: Women with vulvodynia had a marginally increased, yet not significant, prevalence of the catechol-O-methyltransferase genotype that is associated with high activity of the coded protein: 32.9% in the women with vulvodynia, as opposed to 21.5% in the control subjects (odds ratio, 1.80; 95% confidence interval, 1.02-3.15). Subgrouping the cases based on pain frequency revealed that the elevated occurrence of this catechol-O-methyltransferase genotype was present in 40.6% of the subset of women who experienced pain only with sexual intercourse vs only 21.5% of control subjects (odds ratio, 2.50; 95% confidence interval, 1.27-4.93). Also, women with primary vulvodynia had a significantly higher prevalence of the H allele than did the control subjects (62.9% vs 48.1%; odds ratio, 1.82; 95% confidence interval, 1.05-3.17). CONCLUSION: Increased pain sensitivity in women with vulvodynia is not due to a genetically determined low catechol-O-methyltransferase enzyme activity. Other mechanisms may account for alterations in catechol-O-methyltransferase activity in women with pain that is limited to intercourse or primary vulvodynia that contributes to pain sensitivity.

Familiality analysis of provoked vestibulodynia treated by vestibulectomy supports genetic predisposition.

BACKGROUND: Provoked vestibulodynia is a poorly understood disease that affects 8-15% of women in their lifetime. There is significant inflammation and nerve growth in vestibular biopsies from affected women treated by vestibulectomy compared with matched female population controls without vestibulodynia. The triggers leading to this neurogenic inflammation are unknown, but they are likely multifactorial. OBJECTIVE: Our objective was to determine whether vestibulodynia is more common in close and distantly related female relatives of women diagnosed with the disease and those specifically treated by vestibulectomy. Excess familial clustering would support a potential genetic predisposition for vestibulodynia and warrant further studies to isolate risk alleles. STUDY DESIGN: Using population-based genealogy linked to University of Utah Hospital CPT coded data, we estimated the relative risk of vestibulectomy in female relatives of affected women. We also compared the average pairwise relatedness of cases to the expected relatedness of the population and identified high-disease-burden pedigrees. RESULTS: A total of 183 potential vestibulectomy probands were identified using CPT codes. The relative risk of vestibulectomy was elevated in first-degree (20 [6.6-47], P < .00001), second-degree (4.5 [0.5-16], P = .07), and third-degree female relatives (3.4 [1.2-8.8], P = .03). Seventy of these 183 CPT-based probands had available clinical history to confirm a diagnosis of moderate to severe vestibulodynia. Notably, this smaller group of confirmed probands (n = 70) revealed a similar familiality in first-degree (54 [17.5-126], P < .00001), second-degree (19.7 [2.4-71], P = .005), and third-degree relatives (12 [3.3-31], P = .0004), despite less statistical power for analysis. Overall, the average pairwise relatedness of affected women was significantly higher than expected (P < .001) and a number of high-disease-burden Utah families were identified. CONCLUSION: Our data suggest that vestibulodynia treated by vestibulectomy has a genetic predisposition. Future studies will identify candidate genes by linkage analysis in affected families and sequencing of distantly related probands.

Polymorphisms of the androgen receptor gene and hormonal contraceptive induced provoked vestibulodynia.

AIM: Women who developed vestibulodynia (vulvar vestibulitis) while taking combined hormonal contraceptives (CHCs) and a control group of women were tested for polymorphisms of the gene coding for the androgen receptor (AR) that is located on the X chromosome. STUDY DESIGN: DNA from 30 women who developed vestibulodynia while taking CHCs and 17 control women were tested for the number of cytosine-adenine-guanine (CAG) trinucleotide repeats in the AR. In addition, serum-free testosterone was tested in both groups. RESULTS: The mean number of CAG repeats in the study group was significantly greater than the control group (22.05 ± 2.98 vs. 20.61 ± 2.19, respectively; P = 0.025). This significant difference persisted when analyzing the CAG repeats from the longer allele from each subject. Among those who were taking drospirenone-containing CHCs, the mean calculated free testosterone was 0.189 ± 0.115 ng/dL in the study group and 0.127 ± 0.054 ng/dL in the control group, all of whom were taking drospirenone-containing CHCs (P = 0.042). CONCLUSION: In the study cohort, women who developed vestibulodynia while taking CHCs are more likely to have longer CAG repeats in the AR than women who took the same type of CHC but did not develop vestibulodynia. We speculate that the risk of developing CHC-induced vestibulodynia may be due to lowered free testosterone combined with an inefficient AR that predisposes women to vestibular pain.

Serotonin receptor gene (5HT-2A) polymorphism is associated with provoked vestibulodynia and comorbid symptoms of pain.

INTRODUCTION: Provoked vestibulodynia (PVD) is a common type of dyspareunia among young women. The patho-physiology remains largely unclear. Women with PVD have general pain hypersensitivity and often report additional pain symptoms. Signs point towards PVD being a chronic pain disorder similar to other syndromes of longstanding pain, including a common comorbidity of anxiety and depression. Polymorphism in the serotonin receptor gene, 5HT-2A, has been associated with other chronic pain disorders such as fibromyalgia but has not been investigated in PVD patients. AIM: We aimed to investigate a possible contribution of polymorphism in the 5HT-2A gene to the etiology of PVD as well as a potential influence on pain sensitivity. METHODS: In this case-control study 98 women with PVD and 103 healthy controls between 18 and 44 years and in the same menstrual cycle phase completed questionnaires and underwent quantitative sensory testing. Venous blood samples were collected for DNA isolation. MAIN OUTCOME MEASURES: Concomitant pain was reported, a bodily pain score was created and pressure pain thresholds (PPTs) on the arm, leg, and in the vestibule were measured. Intensity of coital pain was rated on a visual analog scale, range 0-100. The T102C (rs6313) and A-1438G (rs6311) single nucleotide polymorphisms (SNPs) in the 5HT-2A gene were analyzed. RESULTS: The probability of PVD was elevated in participants carrying the 1438G- and 102C-alleles of the 5HT-2A gene (OR 2.9). The G-/C- genotypes were also associated with more concomitant bodily pain in addition to the dyspareunia, but not with experimental PPTs or coital pain ratings. PVD patients reported more concomitant bodily pain and had lower PPTs compared with controls. CONCLUSION: The results indicate a contribution of alterations in the serotonergic system to the patho-genesis of PVD and gives further evidence of PVD being a general pain disorder similar to other chronic pain disorders.

GCH1-polymorphism and pain sensitivity among women with provoked vestibulodynia.

BACKGROUND: Provoked vestibulodynia (PVD) is a pain disorder localized in the vestibular mucosa. It is the most common cause of dyspareunia among young women and it is associated with general pain hypersensitivity and other chronic pain conditions. Polymorphism in the guanosine triphosphate cyclohydrolase (GCH1) gene has been found to influence general pain sensitivity and the risk of developing a longstanding pain condition. The aim of this study was to investigate GCH1-polymorphism in women with PVD and healthy controls, in correlation to pain sensitivity. RESULTS: We found no correlation between the previously defined pain-protective GCH1-SNP combination and the diagnosis of PVD. Nor any correlation with pain sensitivity measured as pressure pain thresholds on the arm, leg and in the vestibule, coital pain scored on a visual analog scale and prevalence of other bodily pain conditions among women with PVD (n = 98) and healthy controls (n = 102). However, among patients with current treatment (n = 36), there was a significant interaction effect of GCH1-gene polymorphism and hormonal contraceptive (HC) therapy on coital pain (p = 0.04) as well as on pressure pain thresholds on the arm (p = 0.04). PVD patients carrying the specified SNP combination and using HCs had higher pain sensitivity compared to non-carriers. In non-HC-users, carriers had lower pain sensitivity. CONCLUSIONS: The results of this study gave no support to the hypothesis that polymorphism in the GCH1-gene contributes to the etiology of PVD. However, among patients currently receiving treatment an interaction effect of the defined SNP combination and use of hormonal contraceptives on pain sensitivity was found. This finding offers a possible explanation to the clinically known fact that some PVD patients improve after cessation of hormonal contraceptives, indicating that PVD patients carrying the defined SNP combination of GCH1 would benefit from this intervention.

Immunological and genetic characterization of women with vulvodynia.

Vulvodynia is a complex disorder and described as discomfort or intense burning pain in the vulvar area. Such chronic pain affects 5 to 15% of women and many suffer of misdiagnosis. For sure the aetiology is multifactorial. Through few studies we consider the inflammatory response plays a major role. There is a genetic profile of women suffering of vulvodynia, especially genetic polymorphisms from genes coding for cytokines, Interleukin-1 receptor antagonist and Interleukin-1 beta, and gene coding for mannose-binding lectin (MBL). These polymorphisms result in a stronger inflammatory response and lay these women in a susceptibility situation. Histological analysis showed a chronic no specific inflammation. We have also demonstrated that these patients present in normal state or under infectious induction an inadequate inflammatory response. But there is still a variety of mechanisms which can interact with the inflammatory response. Management of such vulvar pain syndrome could be very frustrating, but the first step for improvement is to get the right diagnosis.