It is therefore thought that Polymorphism genes change the chemical balance of individuals who possess them. If a FM patient possesses this variant gene, their physiological responses are altered, which can increase the amount of pain experienced. The COMT gene has not only been found to alter processes such as heightened pain sensations, to the reality of the harmful stimuli. It has been suggested that the COMT gene is also linked to stress. Gursoy reported that the involvement of COMT gene polymorphism in patients with FM is important adrenergic neurons which are responsible for the transmission of adrenaline (2002). Adrenaline is largely associated with the response to stress. Higher levels of adrenaline, caused by an alteration in adrenergic receptors will increase the physiological changes brought on by neurotransmitter. This also suggests that fibromyalgia is a combination of a variation of regulator genes and environmental stressors. Therefore genetics may make an individual more vulnerable to developing schizophrenia as they are more likely to experience higher levels of responses to stress, stimulated by higher levels of adrenaline. Other researchers have identified polymorph genes involved in the etiology of FMS.Bondy et al studied the polymorphism of the 5-HT2A-receptor gene, which codes for a receptor of serotonin. The researchers compare the 5HT2A receptor gene in 168 FM patients and a group of 115 healthy controls. Bondy et al, found that the distribution of such receptor genes were significantly different in FM patients than controls. Serotonin is involved in the etiology of many disorders including Depression and Obsessive Compulsive Disorder. Tests also found that influences such as age of FM onset, duration of the disorder or psychopathological symptoms had no correlation to the genes studied (Bondy et al., 1999). This suggests that a variant COMT gene can impact up It was concluded by Bondy et al. that the T102C polymorphism is not directly involved in FMS etiology, but might be linked to the variant functionality of the gene. Therefore it is safe to conclude that the variation of the 5-HT2A – receptor gene is due to transfer of the gene from parents. In support of this Cohen et al, genotyped 99 women from two Israeli ethnic groups. Statistical tests compared the association between the serotonin transporter polymorph and anxiety traits. They found there was a significant association between the serotonin transporter polymorphism and personality traits related to anxiety (Cohen et al, 2002). This may explain why some people may be more exposed to anxiety which many FMS sufferers do experience.