[Relationship between COMT gene genotypes and severity of fibromyalgia]

The polymorphism Val158Met in the COMT gene: disrupted dopamine system in fibromyalgia patients?

ABSTRACT

The single-nucleotide polymorphism (SNP) rs4680 in the catechol-O-methyltransferase gene ( COMT ) is a missense variant (Val158Met) associated with altered activity of the COMT enzyme and suggested as a predictive feature for developing some chronic pain conditions. However, there are controversial results on its role in fibromyalgia (FM). Here, the SNP Val158Met was analyzed in 294 FM patients (without comorbidities) and 209 healthy controls (without chronic pain). The concurrent impact of Val158Met genotypes and FM comorbid disorders (depression and sleep impairment) on FM risk were tested. In addition, the genotypic distribution of FM patients in relation to pain intensity was evaluated. The G allele (Val) resulted in being more represented in the FM group (57.8%) compared with the control group (48.8%; P = 0.037). Logistic regression highlighted that having the G/G (Val/Val) homozygous genotype was associated with 2 times higher risk of having FM compared with the A/A (Met/Met) carriers ( P = 0.038), whereas depression and sleep impairment increased FM risk by 12 and 8 times, respectively ( P < 0.001). However, considering only the FM patient group, the A/A homozygous genotype was significantly associated with severe pain intensity ( P = 0.007). This study highlighted associations between the SNP Val158Met and both FM and pain intensity, suggesting a link between dopaminergic dysfunction and vulnerability to chronic pain. Further studies should explore this SNP in FM patients in conjunction with COMT enzymatic activity and other symptoms connected with the dopaminergic system such as depression or sleep impairment.

UNRAVELING THE CLINICO-GENETIC ASSOCIATION OF CATECHOL-O-METHYLTRANSFERASE-RS4680 G>A GENE POLYMORPHISM IN WOMEN WITH FIBROMYALGIA SYNDROME

OBJECTIVE

The aim: To determine the clinical and the genetic association of the COMT rs4680 SNP in women with FMS.

PATIENTS AND METHODS

Materials and methods: Extracted DNA from peripheral blood samples were utilized as template for the PCR and RFLP analysis.

RESULTS

Results: A significant difference was found in the distribution of the COMT genotype between FMS patients and controls (P<0.05). The frequency of GG, AG, AA genotypes were 12%, 72%, 21% in FMS patients and 32%, 62%, 11% in controls. The clinical features of FMS reveal that FIQR and the severity of pain measured by VAS were significantly associated with the COMT rs4680 SNP (P=0.042; P=0.016). The co-dominant model for GG verse v. AG genotype (P=0.004) and AG v. AA genotype (P=0.002) has shown to be high risk for FMS. An increased risk of FMS in the dominant model for (AG+AA) v. GG genotype (P=0.001) and no significant difference was found between (GG+AG) v. AA genotype (P=0.08) in the recessive model. The result indicated that A allele considerably increase the risk of FMS (P=0.004) in comparison to the G allele.

CONCLUSION

Conclusions: AA genotype and A allele of the COMT rs4680 SNP were significantly associated with severity in FMS patients and also plays a significant role in the clinical manifestation of this disease.

Interplay between genetics and lifestyle on pain susceptibility in women with fibromyalgia: The al-Ándalus project

Objectives

It is widely acknowledged that the experience of pain is promoted by both genetic susceptibility and environmental factors such as engaging in physical activity (PA), and that pain-related cognitions are also important. Thus, the purpose of the present study was to test the association of 64 polymorphisms (34 candidate genes) and the gene–gene, gene–PA and gene–sedentary behaviour interactions with pain and pain-related cognitions in women with FM.

Methods

Saliva samples from 274 women with FM [mean (s.d.) age 51.7 (7.7) years] were collected for extracting DNA. We measured PA and sedentary behaviour by accelerometers for a week, pain with algometry and questionnaires, and pain-related cognitions with questionnaires. To assess the robustness of the results, a meta-analysis was also performed.

Results

The rs6311 and rs6313 polymorphisms (5-hydroxytryptamine receptor 2A, HTR2A) were individually related to algometer scores. The interaction of rs4818 (catechol-O-methyltransferase, COMT) and rs1799971 (opioid receptor μ gene, OPRM1) was related to pain catastrophizing. Five gene–behaviour interactions were significant: the interactions of sedentary behaviour with rs1383914 (adrenoceptor alpha 1A, ADRA1A), rs6860 (charged multivesicular body protein 1A, CHMP1A), rs4680 (COMT), rs165599 (COMT) and rs12994338 (SCN9A) on bodily pain subscale of the Short Form 36. Furthermore, the meta-analysis showed an association between rs4680 (COMT) and severity of FM symptoms (codominant model, P-value 0.032).

Conclusion

The HTR2A gene (individually), COMT and OPRM1 gene–gene interaction, and the interactions of sedentary behaviour with ADRA1A, CHMP1A, COMT and SCN9A genes were associated with pain-related outcomes. Collectively, findings from the present study indicate a modest contribution of genetics and gene–sedentary behaviour interaction to pain and pain catastrophizing in women with FM. Future research should examine whether reducing sedentary behaviour is particularly beneficial for reducing pain in women with genetic susceptibility to pain.

Fear of pain moderates the relationship between self-reported fatigue and methionine allele of catechol-O-methyltransferase gene in patients with fibromyalgia

Previous research has shown a consistent association among genetic factors, psychological symptoms and pain associated with fibromyalgia. However, how these symptoms interact to moderate genetic factors in fibromyalgia has rarely been studied to date. The present research investigates whether psychological symptoms can moderate the effects of catechol-O-methyltransferase on pain and fatigue. A total of 108 women diagnosed with fibromyalgia and 77 healthy control participants took part in the study. Pain, fatigue, and psychological symptoms (anxiety, depression, pain catastrophizing, fear of pain and fear of movement) were measured by self-report questionnaires. Two types of statistical analyses were performed; the first was undertaken to explore the influences of COMT genotypes on clinical symptoms by comparing patients with fibromyalgia and healthy controls. In the second analysis, moderation analyses to explore the role of psychological symptoms as potential factors that moderate the relationship between pain/fatigue and COMT genotypes were performed. The main results indicated that patients carrying the Met/Met genotype reported significantly higher levels of fatigue than heterozygote carriers (i.e., Met/Val genotype) and higher levels of fatigue, but not significantly different, than Val homozygote carriers. Among patients with fibromyalgia carrying methionine alleles (i.e., Met/Met + Met/Val carriers), only those who scored high on medical fear of pain, experienced an intensified feeling of fatigue. Thus, the present research suggests that fear of pain, as a psychological symptom frequently described in fibromyalgia may act as a moderating factor in the relationship between the Met allele of the COMT gene and the increase or decrease in self-reported fatigue. Although further research with wider patient samples is needed to confirm the present findings, these results point out that the use of psychological interventions focused on affective symptomatology might be a useful tool to reduce the severity of fibromyalgia.

Fibromyalgia Pain and Depression: An Update on the Role of Repetitive Transcranial Magnetic Stimulation

Fibromyalgia is a musculoskeletal pain of different parts of the body, which is also associated with fatigue, lack of sleep, cognition deficits, family history, gender bias, and other disorders such as osteoarthritis and rheumatoid arthritis. It is generally initiated after trauma, surgery, infection, or stress. Fibromyalgia often coexists with several other conditions or disorders such as temporomandibular joint disorders, bowel and bladder syndrome, anxiety, depression, headaches, and interstitial cystitis. While there is no permanent cure for fibromyalgia, some interventions are available with multiple side effects. rTMS (repetitive transcranial magnetic stimulation), a noninvasive management strategy is used widely for various pain-related etiologies including fibromyalgia in both the laboratory and clinical settings. In this Review, we discuss the role and mechanism of action of rTMS in fibromyalgia patients and on associated comorbidities including anxiety, pain, depression, neurotransmitter alterations, sleep disorders, and overall quality of life of the patients suffering from this chronic problem. We also provide an update on the rTMS application in the clinical trials of fibromyalgia patients and prospective management therapy for multiple problems that these patients suffer.

Comparison of Beta-2 Adrenergic Receptor Gene Polymorphisms Between Patients with Fibromyalgia Syndrome and Healthy Controls

Objectives

This study aims to compare the beta-2 adrenergic receptor (ADRB2) gene polymorphisms of patients with fibromyalgia syndrome (FMS) with those of healthy control subjects, and to investigate the possible relationship between symptoms of FMS and polymorphisms of the ADRB2 gene.

Patients and methods

The study included 170 females (mean age 47.8±10.3 years; range, 21 to 75 years) diagnosed with FMS according to the 2010 American College of Rheumatology criteria and 170 healthy females (mean age 47.2±8.8 years; range, 20 to 72 years) as the control group. Several clinical symptoms of the participants related to FMS were questioned and recorded. The visual analog scale (VAS) and Fibromyalgia Impact Questionnaire (FIQ) scores of the fibromyalgia group were recorded. In both groups, the ADRB2 (rs1042717) single-nucleotide polymorphism was detected by way of a real-time polymerase chain reaction. The wild-type (Guanine/Guanine), the mutant type (Adenine/Adenine) and heterozygous type (Adenine/Guanine) were detected. The sample power was calculated considering the minor allele frequency.

Results

The comparison of the ADRB2 gene polymorphism between patients with FMS and the control subjects showed that the groups were similar in terms of ADBR2 gene polymorphism and genotype (p>0.05). There was no significant difference in terms of genotype when the ADRB2 gene polymorphisms in patients with FMS were compared in terms of clinical symptoms, VAS and FIQ scores (p>0.05).

Conclusion

Beta-2 adrenergic receptor (rs1042717) gene polymorphisms and genotype distribution are no different between patients with FMS and healthy individuals. ADRB2 gene polymorphisms in patients with FMS have no effect on clinical symptoms and VAS and FIQ scores. The results of the present study will light the way for future research into ADRB2 gene polymorphisms in the pathogenesis of FMS.

Effects of COMT Genotypes on Working Memory Performance in Fibromyalgia Patients

Growing research has reported the presence of a clear impairment of working memory functioning in fibromyalgia. Although different genetic factors involving dopamine availability (i.e, the COMT gene) have been associated with the more severe presentation of key symptoms in fibromyalgia, scientific evidence regarding the influence of COMT genotypes on cognitive impairment in these patients is still lacking. To this end, 167 participants took part in the present investigation. Working memory performance was assessed by the application of the SST (Spatial Span Test) and LNST (Letter and Number Sequence Test) belonging to the Weschler Memory Scale III. Significant working memory impairment was shown by the fibromyalgia patients. Remarkably, our results suggest that performance according to different working memory measures might be influenced by different genotypes of the COMT gene. Specifically, fibromyalgia patients carrying the Val/Val genotype exhibited significantly worse outcomes for the span of SST backward, SST backward score, SST total score and the Working Memory Index (WMI) than the Val/Val healthy carriers. Furthermore, the Val/Val patients performed worse on the SST backward and SST score than heterozygotes. Our findings are the first to show a link between the COMT gene and working memory dysfunction in fibromyalgia, supporting the idea that higher COMT enzyme activity would contribute to more severe working memory impairment in fibromyalgia.

The Association Between C-Reactive Protein and Postoperative Delirium Differs by Catechol-O-Methyltransferase Genotype

OBJECTIVE

Catechol-O-methyltransferase (COMT), a key enzyme in degrading catecholamines associated with the stress response, may influence susceptibility to delirium. Individuals with the COMT (rs4680) Val/Val genotype (designated "warriors") withstand the onset of neuropsychiatric disorders and cognitive decline, whereas individuals with Met/Met and Val/Met genotypes ("nonwarriors") are more susceptible to these conditions. We evaluated whether COMT genotype modifies the established association between acute phase reactant (stress marker) C-reactive protein (CRP) and postoperative delirium.

METHODS

This was a prospective cohort study conducted at two academic medical centers. The study involved 547 patients aged 70 or older undergoing major noncardiac surgery. We collected blood, extracted DNA, and performed COMT genotyping using allele-specific polymerase chain reaction assays, considering warriors versus nonwarriors. High plasma CRP, measured on postoperative day 2 using enzyme-linked immunosorbent assay, was defined by the highest sample-based quartile (≥234.12 mg/L). Delirium was determined using the Confusion Assessment Method, augmented by a validated chart review. We used generalized linear models adjusted for age, sex, surgery type, and race/ethnicity, stratified by COMT genotype, to determine whether the association between CRP and delirium differed by COMT.

RESULTS

Prevalence of COMT warriors was 26%, and postoperative delirium occurred in 23%. Among COMT warriors, high CRP was not associated with delirium (relative risk [RR] 1.0, 95% confidence interval [CI] 0.4-2.6). In contrast, among nonwarriors, we found the expected relationship of high CRP and delirium (RR 1.5, 95% CI 1.1-2.2).

CONCLUSION

COMT warriors may be protected against the increased risk of delirium associated with high CRP on postoperative day 2. With further confirmation, COMT genotype may help target interventions for delirium prevention in the vulnerable nonwarrior group.

Fibromyalgia: A Critical and Comprehensive Review

Fibromyalgia is a disorder that is part of a spectrum of syndromes that lack precise classification. It is often considered as part of the global overview of functional somatic syndromes that are otherwise medically unexplained or part of a somatization disorder. Patients with fibromyalgia share symptoms with other functional somatic problems, including issues of myalgias, arthralgias, fatigue and sleep disturbances. Indeed, there is often diagnostic and classification overlap for the case definitions of a variety of somatization disorders. Fibromyalgia, however, is a critically important syndrome for physicians and scientists to be aware of. Patients should be taken very seriously and provided optimal care. Although inflammatory, infectious, and autoimmune disorders have all been ascribed to be etiological events in the development of fibromyalgia, there is very little data to support such a thesis. Many of these disorders are associated with depression and anxiety and may even be part of what has been sometimes called affected spectrum disorders. There is no evidence that physical trauma, i.e., automobile accidents, is associated with the development or exacerbation of fibromyalgia. Treatment should be placed on education, patient support, physical therapy, nutrition, and exercise, including the use of drugs that are approved for the treatment of fibromyalgia. Treatment should not include opiates and patients should not become poly pharmacies in which the treatment itself can lead to significant morbidities. Patients with fibromyalgia are living and not dying of this disorder and positive outlooks and family support are key elements in the management of patients.

Review of overlap between thermoregulation and pain modulation in fibromyalgia

Fibromyalgia (FM) syndrome is characterized by widespread pain that is exacerbated by cold and stress but relieved by warmth. We review the points along thermal and pain pathways where temperature may influence pain. We also present evidence addressing the possibility that brown adipose tissue activity is linked to the pain of FM given that cold initiates thermogenesis in brown adipose tissue through adrenergic activity, whereas warmth suspends thermogenesis. Although females have a higher incidence of FM and more resting thermogenesis, they are less able to recruit brown adipose tissue in response to chronic stress than males. In addition, conditions that are frequently comorbid with FM compromise brown adipose activity making it less responsive to sympathetic stimulation. This results in lower body temperatures, lower metabolic rates, and lower circulating cortisol/corticosterone in response to stress--characteristics of FM. In the periphery, sympathetic nerves to brown adipose also project to surrounding tissues, including tender points characterizing FM. As a result, the musculoskeletal hyperalgesia associated with conditions such as FM may result from referred pain in the adjacent muscle and skin.

Association between the COMT Val158Met polymorphism and fibromyalgia susceptibility and fibromyalgia impact questionnaire score: a meta-analysis

The aim of this study was to explore whether the catechol-O-methyltransferase (COMT) Val158Met polymorphism is associated with susceptibility to fibromyalgia and fibromyalgia impact questionnaire (FIQ) score in fibromyalgia patients. We conducted a meta-analysis of the associations of the COMT Val158Met polymorphism with fibromyalgia risk as well as FIQ score in fibromyalgia patients. A total of 993 fibromyalgia patients and 778 controls from 10 studies on the COMT Val158Met polymorphism and 538 fibromyalgia patients from 5 studies on the COMT Val158Met polymorphism and FIQ score were included in this meta-analysis. The meta-analysis revealed an association between fibromyalgia and the COMT Met/Met + Val/Met genotype in all study subjects (odds ratio (OR) 1.635, 95 % confidence interval (CI) 1.029-2.597, p = 0.037). However, stratification by ethnicity indicated no association between the Met/Met + Val/Met genotype and fibromyalgia in the European and Turkish populations (OR 1.202, 95 % CI 0.876-1.649, p = 0.255; OR 2.132, 95 % CI 0.764-5.949, p = 0.148, respectively). Analysis using other genetic models showed no association between the COMT Val158Met polymorphism and fibromyalgia. The meta-analysis also revealed that the FIQ score was significantly higher in individuals with the COMT Met/Met genotype than in those with the Val/Val genotype [weighted mean difference (WMD) = 14.39, 95 % CI 3.316-25.48, p = 0.011] and the Val/Met genotype (WMD = 5.108, 95 % CI 2.212-4.891, p = 0.021). This meta-analysis identified an association between fibromyalgia risk and the COMT Val158Met polymorphism as well as the FIQ score in fibromyalgia patients.

Janus molecule I: dichotomous effects of COMT in neuropathic vs nociceptive pain modalities

The enzyme catechol-O-methyltransferase (COMT) has been shown to play a critical role in pain perception by regulating levels of epinephrine (Epi) and norepinephrine (NE). Although the key contribution of catecholamines to the perception of pain has been recognized for a long time, there is a clear dichotomy of observations. More than a century of research has demonstrated that increasing adrenergic transmission in the spinal cord decreases pain sensitivity in animals. Equally abundant evidence demonstrates the opposite effect of adrenergic signaling in the peripheral nervous system, where adrenergic signaling increases pain sensitivity. Viewing pain processing within spinal and peripheral compartments and determining the directionality of adrenergic signaling helps clarify the seemingly contradictory findings of the pain modulatory properties of adrenergic receptor agonists and antagonists presented in other reviews. Available evidence suggests that adrenergic signaling contributes to pain phenotypes through α(1/2) and β(2/3) receptors. While stimulation of α(2) adrenergic receptors seems to uniformly produce analgesia, stimulation of α(1) or β receptors produces either analgesic or hyperalgesic effects. Establishing the directionality of adrenergic receptor modulation of pain processing, and related COMT activity in different pain models are needed to bring meaning to recent human molecular genetic findings. This will enable the translation of current findings into meaningful clinical applications such as diagnostic markers and novel therapeutic targets for complex human pain conditions.

Genetic contribution of catechol-O-methyltransferase polymorphism (Val158Met) in children with chronic tension-type headache

Our aim was to investigate the relationship between Val158Met polymorphisms, headache, and pressure hypersensitivity in children with chronic tension-type headache (CTTH). A case-control study with blinded assessor was conducted. Seventy children with CTTH associated with pericranial tenderness and 70 healthy children participated. After amplifying Val158Met polymorphism by polymerase chain reactions, we assessed genotype frequencies and allele distributions. We classified children according to their Val158Met polymorphism: Val/Val, Val/Met, Met/Met. Pressure pain thresholds (PPT) were bilaterally assessed over the temporalis, upper trapezius, second metacarpal, and tibialis anterior muscles. The distribution of Val158Met genotypes was not significantly different (p = 0.335), between children with CTTH and healthy children, and between boys and girls (p = 0.872). Children with CTTH with the Met/Met genotype showed a longer headache history compared with those with Met/Val (p = 0.001) or Val/Val (p = 0.002) genotype. Children with CTTH with Met/Met genotype showed lower PPT over upper trapezius and temporalis muscles than children with CTTH with Met/Val or Val/Val genotype (p < 0.01). The Val158Met catechol-O-methyltransferase (COMT) polymorphism does not appear to be involved in predisposition to suffer from CTTH in children; nevertheless, this genetic factor may be involved in the phenotypic expression, as pressure hypersensitivity was greater in those CTTH children with the Met/Met genotype.

Influence of catechol-O-methyltransferase (COMT) gene polymorphisms in pain sensibility of Brazilian fibromialgia patients

Fibromyalgia syndrome (FS) is a rheumatic syndrome affecting to 2-3% of individuals of productive age, mainly women. Neuroendocrine and genetic factors may play a significant role in development of the disease which is characterized by diffuse chronic pain and presence of tender points. Several studies have suggested an association between FS, especially pain sensitivity, and polymorphism of the catechol-O-methyltransferase (COMT) gene. The aim of the present study was to characterize the SNPs rs4680 and rs4818 of the COMT gene and assess its influence in pain sensitivity of patients with fibromyalgia screened by the Fibromyalgia Impact Questionnaire (FIQ). DNA was extracted from peripheral blood of 112 patients with fibromyalgia and 110 healthy individuals and was used as template in PCR for amplification of a 185-bp fragment of the COMT gene. The amplified fragment was sequenced for analyses of the SNPs rs4680 and rs4818. The frequency of mutant genotype AA of SNP rs6860 was 77.67% in patients with FS and 28.18% for the control group. For the SNP rs4818, the frequency of mutant genotype CC was 73.21 and 39.09% for patients with FS and controls, respectively. Moreover, the FIQ score was higher in patients with the homozygous mutant genotype for SNPs rs4680 (87.92 points) and rs4818 (86.14 points). These results suggest that SNPs rs4680 and rs4818 of the COMT gene may be associated with fibromyalgia and pain sensitivity in FS Brazilian patients.

Catechol-O-methyltransferase gene haplotypes in Mexican and Spanish patients with fibromyalgia

Autonomic dysfunction is frequent in patients with fibromyalgia (FM). Heart rate variability analyses have demonstrated signs of ongoing sympathetic hyperactivity. Catecholamines are sympathetic neurotransmitters. Catechol-O-methyltransferase (COMT), an enzyme, is the major catecholamine-clearing pathway. There are several single-nucleotide polymorphisms (SNPs) in the COMT gene associated with the different catecholamine-clearing abilities of the COMT enzyme. These SNPs are in linkage disequilibrium and segregate as 'haplotypes'. Healthy females with a particular COMT gene haplotype (ACCG) producing a defective enzyme are more sensitive to painful stimuli. The objective of our study was to define whether women with FM, from two different countries (Mexico and Spain), have the COMT gene haplotypes that have been previously associated with greater sensitivity to pain. All the individuals in the study were female. Fifty-seven Mexican patients and 78 Spanish patients were compared with their respective healthy control groups. All participants filled out the Fibromyalgia Impact Questionnaire (FIQ). Six COMT SNPs (rs2097903, rs6269, rs4633, rs4818, rs4680, and rs165599) were genotyped from peripheral blood DNA. In Spanish patients, there was a significant association between three SNPs (rs6269, rs4818, and rs4680) and the presence of FM when compared with healthy controls. Moreover, in Spanish patients with the 'high pain sensitivity' haplotype (ACCG), the disease, as assessed by the FIQ, was more severe. By contrast, Mexican patients displayed only a weak association between rs6269 and rs165599, and some FIQ subscales. In our group of Spanish patients, there was an association between FM and the COMT haplotype previously associated with high pain sensitivity. This association was not observed in Mexican patients. Studies with a larger sample size are needed in order to verify or amend these preliminary results.

Biology and therapy of fibromyalgia. Stress, the stress response system, and fibromyalgia

Stress is a state of disharmony, or threatened homeostasis. A stressor could have a psychological origin or a biological origin. Societies have become more intricate with industrialization, and modern individuals try to adapt to the new defiance by forcing their stress response system. The main component of the stress response network is the autonomic nervous system. The present article reviews current knowledge on autonomic dysfunction in fibromyalgia. Sympathetic hyperactivity has been consistently described by diverse groups of investigators. Fibromyalgia is proposed to be a sympathetically maintained neuropathic pain syndrome, and genomic data support this contention. Autonomic dysfunction may also explain other fibromyalgia features not related to pain.