Open Access
Open Peer Review

This article has Open Peer Review reports available.

How does Open Peer Review work?

Synaptosomal-associated protein 25 (Snap-25) gene Polymorphism frequency in fibromyalgia syndrome and relationship with clinical symptoms

  • Ayse Balkarli1Email author,
  • Cem Sengül2,
  • Emre Tepeli3,
  • Huseyin Balkarli4 and
  • Veli Cobankara1
BMC Musculoskeletal Disorders201415:191

DOI: 10.1186/1471-2474-15-191

Received: 27 December 2013

Accepted: 21 May 2014

Published: 31 May 2014



SNAP-25 protein is contributory to plasma membrane and synaptic vesicle fusions that are critical points in neurotransmission. SNAP-25 gene is associated with behavioral symptoms, personality and psychological disorders. In addition, SNAP-25 protein can be related to different neurotransmitter functions due to its association with vesicle membrane transition and fusion. This is important because neurologic, cognitive, and psychologic disorders in fibromyalgia syndrome (FMS) can be related to this function. This relationship may be enlightening for etiopathogenesis of FMS and treatment approaches. We aimed to study a SNAP-25 gene polymorphism, which is related to many psychiatric diseases, and FMS association in this prospective study.


We included 71 patients who were diagnosed according to new criteria and 57 matched healthy women in this study. Both groups were evaluated regarding age, height, weight, BMI, education level, marital and occupational status. A new diagnosis of FMS was made from criteria scoring, SF-36, Beck depression scale, and VAS that were applied to the patient group. SNAP-25 gene polymorphism and disease activity score correlations were compared.


Mean age was 38±5,196 and 38.12±4.939 in patient and control groups, respectively (p=0.542). No significant difference was found between groups regarding age, height, weight, BMI, education level, marital or occupational status (p > 0.05). Ddel T/C genotype was significantly higher in the patient group (p = 0.009). MnlI gene polymorphism did not show a correlation with any score whereas a significant correlation was found between Ddel T/C genotype and Beck depression scale and VAS score (p < 0.05).


FMS etiopathogenesis is not clearly known. Numerous neurologic, cognitive and psychological disorders were found during studies looking at cause. Our study showed increased SNAP-25 Ddel T/C genotype in FMS patients compared to the control group, which is related to behavioral symptoms, personality and psychological disorders in FMS patients.


Fibromyalgia Synaptosomal-associated protein 25 gene polymorphism


Fibromyalgia syndrome (FMS) is a non-inflammatory rheumatologic disease characterized by widespread musculoskeletal pain, lethargy and tenderness without a definite cause [1]. FMS diagnosis is used for heterogeneous pathological states including anxiety disorders, depression, lethargy, sleep disorders, and gastrointestinal system symptoms with widespread pain [2]. One of the reasons that FMS is thought to be such a heterogeneous disease may be due to concurrent psychological disorders. Indeed, psychiatric symptoms are very common in this syndrome, and they influence the course of the disease [3, 4]. FMS patients are reported to have increased depression, anxiety and bipolar disorder comorbidities [3, 5]. Several studies determined disorders in personality inventory profiles based on the thought that some personality and mood disorders might predispose to FMS [68].

Dopamine is an important mediator in both psychopathological incidents and pain conduction. Dopamine D2 receptor sensitivity and density are increased in FMS patients [9]. Also, dopamine D4 receptor gene polymorphism is found to be relevant to FMS personality profile [10].

SNAP-25 protein is contributory to plasma membrane and synaptic vesicle [11]. SNAP-25 forms complexes with synaptobrevin in synaptic vesicles and with syntaxin in the plasma membrane [11]. In simple terms, SNAP-25 protein is critical in neurotransmission for fusion of plasma membrane and synaptic vesicle. Several studies investigated the relationship between SNAP-25 gene polymorphism and personality disorders, schizophrenia, and attention deficit and hyperactivity disorder; these studies reported that the SNAP-25 gene might influence development of these disorders [1217]. Furthermore, SNAP-25 protein might be relevant to other different neurotransmitters due to its involvement in vesicle membrane transition and fusion. This is important because it can be the main reason behind neurological, cognitive, psychological disorders in FMS. If such a relationship exists, it will be enlightening for etiopathogenesis of FMS and treatment approaches. We aimed to evaluate the SNAP-25 gene (MnlI = rs3746544 and DdeI = rs1051312) polymorphism, which is related to many psychiatric diseases, and FMS association in this prospective study.

Patients and methods

Patients and evaluation

We included 71 female patients diagnosed with ACR 2010 fibromyalgia diagnosis criteria and 57 age-matched healthy females in the study. Patients and healthy volunteers were informed about the genetic evaluation and informed consent was taken. Blood (10 cc) was taken into EDTA tubes from both the patient and control groups and stored at -20°C. FMS new diagnosis criteria scoring (ACR 2010), VAS, SF-36, and Beck depression scale were applied to the patient group. SNAP-25 gene polymorphism prevalence and SNAP-25 polymorphism with disease activation association were compared. The Local ethics council of Pamukkale University Clinical Research Ethics Committee approved the study. Patient consent was obtained for this study.


A sociodemographic information form was developed by the researchers and includes patient’s age, sex, education, socioeconomic status, settlement, marital status and disease period. The Beck depression scale (BDS) was used for determining the risk for depression, levels of depressive symptoms and difference of intensity. It was developed by Beck et al. and adapted to Turkish by Hisli (Hisli 1989). The VAS consists of 3 parts for measuring pain. The scale was adapted to Turkish and used in numerous studies. The SF-36 scale to determine quality of life was subjected to validity and reliability testing for its use in Turkish.

Molecular analysis

Genetic evaluation was done in our university’s Medical Genetics Department. Patient and control genomic DNA was isolated from peripheral blood by a DNA Extraction Kit. The SNAP-25 genes MnlI (rs3746544) and DdeI (rs1051312) polymorphisms are on the 8th exon (Forward 5′- TTC TCC TCC AAA TGC TGT CG-3′ and Reverse 5′- CCA CCG AGG AGA GAA AAT G-3′ primary series were used to replicate the UTR region).

In addition to these primer series, we also used 10X PCR Buffer, 5 μl dNTP mix consisting of 0.2 mM of every nucleotide and Taq polymerase enzyme. PCR reaction conditions were 95 degrees C for 2 minutes of denaturation followed by 95 degrees C for 45 seconds, 58 degrees C for 1 min, 72 degrees C for 2 minutes of 35 cycles and final elongation at 72 degrees C for 7 minutes.

10 U Ddel and 10 U MnlI enzymes were added separately to obtained 261 bp PCR products and this was incubated for 14 hours at 37°C for cutting. 3.5% Ultra pure agorose jelly was prepared for separating fragments after cutting. Later, PCR products were subjected to 40–50 minutes of electrophoresis and fragmented. After electrophoresis, the allele band series expected for Ddel polymorphism: for T allele: 261 bp cut band, for C allele: 228 bp and 33 bp two separate bands. The allele band series expected for MnlI polymorphism: for T allele: 256 bp and 5 bp two separate bands, for G allele: 210 bp, 46 bp and 5 bp three separate bands.

Statistical analysis

For statistical analysis SPSS version 20 was used. Descriptive statistics were given as mean, standard deviation and percentage. Out study’s confidence interval was 95%. Intergroup significance was evaluated with Chi square test for qualitative data and Mann–Whitney U test for quantitative data. Quantitative data relationships were evaluated with Spearman correlation test. Non parametric variance analysis was done between genetic polymorphisms. p < 0.05 was considered as significant.


Mean age was 38±5,196 and 38.12±4.939 in patient and control groups, respectively (p=0.542). No significant difference was found between the groups regarding age, height, weight, BMI, education, settlement, marital or occupational status (p > 0.05) (Table 1). We determined MnlI gene polymorphism for TT genotype in 30 (42.3%), TG genotype in 34 (47.9%) and GG genotype in 7 (9.9%) patients. Control group had TT genotype in 27 (47.4%), TG genotype in 19 (33.3%) and GG genotype in 11 (19.3) patients. Dde1 genotype variance in patient group was as follows: TT genotype in 29 (40.8%), TC genotype in 40 (56.3%), TC genotype in 17 (29.8%) and CC genotype in 4 (7%). Intergroup SNAP-25 Mnl1 polymorphism variance was not significantly different (Table 2). Dde1 polymorphism variance between groups showed significant difference (p = 0.009). To determine the reason behind this significance, separate match evaluation was applied and TC genotype was discovered to be the reason. Patient and control groups Mnl1 and Dde1 polymorphism variance is given in Table 2.
Table 1

Demographic findings of patient and control groups


Patient (n=71)

Control (n=57)






Number of labor




Number of children




Settlement n (%)


57 (80.3)

45 (75)



14 (19.7)

15 (25)

Marital status n (%)


69 (97.2)

56 (98.25)



2 (2.8)

1 (1.75)

Occupation n (%)


21 (29.57)

17 (29.82)


Not working

50 (70.43)

40 (70.18)

Table 2

Mnl1 and Dde1 polymorphism variance in patient and control groups


Patient n (%)

Control n (%)


Mnl1 gene


30 (42.3)

27 (47.4)



34 (47.9)

19 (33.3)


7 (9.9)

11 (19.3)

Dde1 gene


29 (40.8)

36 (63.2)



40 (56.3)

17 (29.8)


2 (2.8)

4 (7)

We evaluated fibromyalgia new diagnosis criteria and their subscores, Beck depression scale, visual analogue scale (VAS), short form-36 (SF-36) subparameter scores (Table 3). Non parametric variance analyses between genetic polymorphisms were applied. When evaluated for Mnl1 polymorphism individuals for all three (TT, TG, GG) genotypes, VAS, BDS and SF-36 did not show significant differences (p > 0.05). When evaluated for Dde1 polymorphism individuals for all three (TT, TC, CC) genotypes, no significant difference was found for TT and CC individuals; however, TC genotype individuals were significantly higher for BDS (p = 0.045) and VAS scores (p = 0.033) (Table 4). This difference was significant after Bonferoni correction between the groups.
Table 3

Fibromyalgia new diagnostic criteria, VAS, Beck depression scale, SF-36 scores for patients



Fibromyalgia new criteria





Not rested




Part 2a


Part 2b







Physical function


Physical role difficulty




General Health




Social function


Emotional role


Mental health


Table 4

VAS and BDI scores according to the presence TC genotypes


All patients

TC (+)

TC (-)













The etiopathogenesis of FMS, which is characterized by widespread musculoskeletal pain and tenderness, is not clearly understood. FMS, chronic lethargy syndrome, irritable intestine syndrome, tension type headache, and myofacial pain syndrome are parts of central sensitization syndromes. Every one of these syndromes overlaps with FMS. One common feature of these syndromes is increased central neuron stimulation through various synaptic and neurotransmitter/neurochemical activities without structural pathology. This, however, is characterized by increased sensitivity to pressure and touch. Many factors contribute to central sensitization syndrome. These include pain, lethargy, sleep disorder, sensitivity to several stimuli, and psychosocial problems.

For the past several years, environmental as well as genetic conditions are blamed for FMS and related functional somatic disorders such as irritable intestine syndrome, migraine, and chronic lethargy syndrome [1820]. Several studies tried to explain the etiopathogenesis of fibromyalgia syndrome. These studies showed that serum and central nervous system serotonin and its metabolite levels are low, and serotonin transport velocity in cerebrospinal fluid is slow. For this reason, the serotonin transport gene region has been brought to attention. Offenbaecher et al. reported that the S/S genotype is increased in FMS patients when compared to healthy subjects [21].

Dopamine is another molecule that is generating research interest, which has a role in both psychopathologic incidents and pain transport. Studies determined both dopamine levels and dopamine receptor gene polymorphisms and FMS [9, 10, 22, 23].

It is known that psychiatric disorders, especially depression and anxiety disorder are quite common in FMS patients [3]. Several studies reported depression prevalence in FMS between 20% and 80% [3, 4, 7]. It is reported that FMS patients have difficulty in both understanding their own feelings and coping with emotions. Several studies determined disorders in personality inventory profiles based on the thought that some personality and mood disorders might predispose to FMS. When the personality inventory of patients was evaluated, hypochondriasis, hysteria, paranoia, and depression scales were found to be higher than control groups [68]. Studies indicated that low ability to cope with everyday problems can trigger FMS or can increase symptom intensity [6, 8]. As a result, some psychiatric disorders are more prevalent in FMS, and some personality and mood features can predispose to FMS development.

Nevertheless, the relationship between these situations and FMS is not clearly known. Psychiatric disorders are increased in FMS and are relevant to symptom intensity [4, 7]. Some personality and mood features can predispose to FMS, in addition to these features revealing themselves as a result of stress for coping with pain [24, 25].

There can be common pathophysiological features between FMS and psychiatric disorders and personalities. Dopamine and serotonin mediated neurotransmitter transport can be among these common biological factors [23]. However, these disorders have some common risks such as exposure to difficult experience. These factors cause stress in the patient, and prolonged stress leads to cytokine secretion. Increased cytokines precipitate both psychiatric diseases and increased pain perception [26, 27].

It is impossible to explain only one cause for FMS and the etiopathogenesis of these disorders. In addition, the relationship between concurrent disorders and FMS is not clearly known.

SNARE (s oluble N-ethylmaleimide-sensitive factor a ctivating protein re ceptor) proteins have a role in fusion between organelles, and organelles with plasma membrane in eukaryotic cells. SNAP-25 is a SNARE protein found in the plasma membrane. These proteins have important roles in electrical conduction in nerve cells. Nerve transporters are found in synaptic vesicles and sent by exocytosis to the other synapse. For this reason, SNAP-25 affects dopamine and other neurotransmitter secretions, and thus adds to FMS pathogenesis. Therefore, SNARE like proteins should be studied carefully, leading to better understanding of etiopathogenesis and treatment approaches. Also, the relationship between FMS and concurrent psychiatric disorders and personality features can be explained. For this purpose, we found increased SNAP-25 Dde1 TC gene polymorphism in FMS patients in this prospective study. In individuals with the TC gene genotype, BDS and VAS scores were found to be significantly higher than in individuals without TC genotype. FMS is one of the central sensitization syndromes. One mutual property of these diseases is that neurons have increased stimulus mediated by several synaptic and neurotransmitter/neurochemical activities without structural pathology. This results in increased reaction to basic stimuli. Patients who have the TC genotype have increased BSD and VAS scores in our study, which can result from different affected neurotransmitter functions both from this polymorphism and in pain transport. There are no studies done in this matter, and our results should be compared with similar studies.

The primary limitation of this study is trying to explain a complex disease such as FMS with only one mutation with a small number of patients. With more patients and other polymorphisms related to the disease, it will help us understand FMS better in the future.


FMS etiopathogenesis is not clearly known. Numerous neurologic, cognitive and psychological disorders were found during studies attempting to identify cause. Our study showed increased SNAP-25 Ddel T/C genotype in patients compared to controls, which is related with behavioral symptoms, personality and psychological disorders in FMS patients.


Authors’ Affiliations

Department of Internal Medicine, Division of Rheumatology, Pamukkale University Hospital
Department of Psychiatry, Pamukkale University Hospital
Department of Medical Biology, Pamukkale University Hospital
Department of Orthopedics and Traumatology, Akdeniz University Hospital


  1. Chakrabarty S, Zoorob R: Fibromyalgia. Am Fam Physician. 2007, 76: 247-254.PubMedGoogle Scholar
  2. Fries E, Hesse J, Hellhammer J, Hellhammer DH: A new view on hypocortisolism. Psychoneuroendocrinology. 2005, 30: 1010-1016. 10.1016/j.psyneuen.2005.04.006.View ArticlePubMedGoogle Scholar
  3. Thieme K, Turk DC, Flor H: Comorbid depression and anxiety in fibromyalgia syndrome: relationship to somatic and psychosocial variables. Psychosom Med. 2004, 66 (6): 837-844. 10.1097/01.psy.0000146329.63158.40.View ArticlePubMedGoogle Scholar
  4. Fietta P, Fietta P, Manganelli P: Fibromiyalgia and psychiatric disorders. Acta Biomed. 2007, 78: 88-95.PubMedGoogle Scholar
  5. Katz RS, Heard AR, Mills M, Leavitt F: The prevalence and clinical impact of reported cognitive difficulties (fibrofog) in patients with rheumatic disease with and without fibromyalgia. J Clin Rheumatol. 2004, 10: 53-58. 10.1097/01.rhu.0000120895.20623.9f.View ArticlePubMedGoogle Scholar
  6. Gupta A, Silman AJ, Ray D, Morriss R, Dickens C, MacFarlane GJ, Chiu YH, Nicholl B, McBeth J: J The role of psychosocial factors in predicting the onset of chronic widespread pain: results from a prospective population-based study. Rheumatology. 2007, 46: 666-671.View ArticlePubMedGoogle Scholar
  7. Arnold LM, Hudson JI, Keck PE, Auchenbach MB, Javaras KN, Hess EV: Comorbidity of fibromiyalgia and psychiatric disorders. J Clin Psychiatry. 2006, 67: 1219-1225. 10.4088/JCP.v67n0807.View ArticlePubMedGoogle Scholar
  8. Parrish BP, Zautra AJ, Davis MC: The role of positive and negative interpersonal events on daily fatigue in women with fibromyalgia, rheumatoid arthritis, and osteoarthritis. Health Psychol. 2008, 27: 694-702.View ArticlePubMedPubMed CentralGoogle Scholar
  9. Malt EA, Olafsson S, Aakvaag A, Lund A, Ursin H: Altered dopamine D2 receptor function in fibromyalgia patients: a neuroendocrine study with buspirone in women with fibromyalgia compared to female population based controls. J Affect Disord. 2003, 75: 77-82. 10.1016/S0165-0327(02)00025-3.View ArticlePubMedGoogle Scholar
  10. Buskila D, Cohen H, Neumann L, Ebstein RP: An association between fibromyalgia and the dopamine D4 receptor exon III repeat polymorphism and relationship personality traits. Mol Psychiatry. 2004, 9: 730-731. 10.1038/ ArticlePubMedGoogle Scholar
  11. Hu C, Ahmed M, Melia TJ, Söllner TH, Mayer T, Rothman JE: Fusion of cells by flipped SNAREs. Science. 2003, 300: 1745-1749. 10.1126/science.1084909.View ArticlePubMedGoogle Scholar
  12. Faraone SV, Perlis RH, Doyle AE, Smoller JW, Goralnick JJ, Holmgren MA, Sklar P: Molecular genetics of attention-deficit/hyperactivity disorder. Biol Psychiatry. 2005, 57: 1313-1323. 10.1016/j.biopsych.2004.11.024.View ArticlePubMedGoogle Scholar
  13. Corradini L, Verderio C, Sala M, Wilson MC, Matteoli M: SNAP-25 in neuropsychiatric disorders. Ann N Y Acad Sci. 2009, 1152: 93-99. 10.1111/j.1749-6632.2008.03995.x.View ArticlePubMedPubMed CentralGoogle Scholar
  14. Golimbet VE, Alfimova MV, Gritsenko IK, Lezheiko TV, Lavrushina OM, Abramova LI, Kaleda VG, Barkhatova AN, Sokolov AV, Ebstein RP: Association between a synaptosomal-associated protein (SNAP-25) gene polymorphism and verbal memory and attention in patients with endogenous psychoses and mentally healthy subjects. Neurosci Behav Physiol. 2010, 40: 461-465. 10.1007/s11055-010-9280-x.View ArticlePubMedGoogle Scholar
  15. Spellmann I, Müller N, Musil R, Zill P, Douthet A, Dehning S, Cerovecki A, Bondy B, Möller HJ, Riedel M: Associations of SNAP-25 polymorphisms with cognitive dysfunctions in Caucasian patients with schizophrenia during a brief trail of treatment with atypical antipsychotics. Eur Arch Psychiatry Clin Neurosci. 2008, 258: 335-344. 10.1007/s00406-007-0800-9.View ArticlePubMedGoogle Scholar
  16. Gosso MF, De Geus EJ, van Belzen MJ, Polderman TJ, Heutink P, Boomsma DI, Posthuma D: The SNAP-25 gene is associated with cognitive ability: evidence from a family-based study in two independent Dutch cohorts. Mol Psychiatry. 2006, 11: 878-886. 10.1038/ ArticlePubMedGoogle Scholar
  17. Semiz UB, Basoglu C, Oner O, Munir KM, Ates A, Algul A, Ebrinc S, Cetin M: Effects of diagnostic comorbidity and dimensional symptoms of attention-deficit-hyperactivity disorder in men with antisocial personality disorder. Aust N Z J Psychiatry. 2008, 42: 405-413. 10.1080/00048670801961099.View ArticlePubMedPubMed CentralGoogle Scholar
  18. Buskila D, Sarzi-Puttini P: Biology and therapy of fibromyalgia. Genetic aspects of fibromyalgia syndrome. Arthritis Res Ther. 2006, 8: 218-223. 10.1186/ar2005.View ArticlePubMedPubMed CentralGoogle Scholar
  19. Ablin JN, Cohen H, Buskila D: Mechanisms of Disease: genetic of fibromyalgia. Nat Clin Pract Rheumatol. 2006, 2: 671-678. 10.1038/ncprheum0349.View ArticlePubMedGoogle Scholar
  20. Gürsoy S, Erdal E, Herken H, Madenci E, Alasehirli B: Association of T102C polymorphism of the 5-HT2A receptor gene with pyschiatric status in fibromyalgia syndrome. Rheumatol Int. 2001, 21: 58-61. 10.1007/s002960100130.View ArticlePubMedGoogle Scholar
  21. Offenbaecher M, Bondy B, de Jong S, Glatzeder K, Kruger M, Schoeps P, Ackenheil M: Possible association of fibromyalgia with a polymorphism in the regulatory region. Arthritis Rheum. 1999, 42: 2482-2488. 10.1002/1529-0131(199911)42:11<2482::AID-ANR27>3.0.CO;2-B.View ArticlePubMedGoogle Scholar
  22. Holman AJ, Myers RR: A randomized, double blind placebo controlled trial of pramipexole, a dopamine agonist in patients with fibromyalgia receiving concomitant medications. Arthritis Rheum. 2005, 52: 2495-2505. 10.1002/art.21191.View ArticlePubMedGoogle Scholar
  23. Bradley LA: Pathophysiologic mechanisms of fibromyalgia and its related disorders. J Clin Psychiatry. 2008, 69 (Suppl 2): 6-13.PubMedGoogle Scholar
  24. Van Houdenhove B, Neerinckx E, Onghena P, Lysens R, Vertommen H: Premorbid ‘overactive’; lifestyle in chronic fatigue syndrome and fibromyalgia. An etiological factor or prof of good citizenship?. J Psychosom Res. 2001, 51 (4): 571-576. 10.1016/S0022-3999(01)00247-1.View ArticlePubMedGoogle Scholar
  25. Van Houdenhove B, Neerinckx E, Lysens R, Vertommen H, Van Houdenhove L, Onghena P, Westhovens R, D'Hooghe MB: Victimization in chronic fatique syndrome and fibromyalgia in tertiary care: a controlled study on prevalence and characteristics. Psychosomatics. 2001, 42: 21-28. 10.1176/appi.psy.42.1.21.View ArticlePubMedGoogle Scholar
  26. Maier SF: Bi-directional immune-brain communication: Implications for understanding stres, pain, and cognition. Brain Behav Immun. 2003, 17: 69-85. 10.1016/S0889-1591(03)00032-1.View ArticlePubMedGoogle Scholar
  27. Anisman H, Merali Z: Cytokines, stres and depressive illness: brain-immune interactions. Ann Med. 2003, 35: 2-11. 10.1080/07853890310004075.View ArticlePubMedGoogle Scholar
  28. Pre-publication history

    1. The pre-publication history for this paper can be accessed here:


© Balkarli et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.