Catechol-O-methyltransferase Val158Met polymorphism influences anxiety, depression, and disability, but not pressure pain sensitivity, in women with fibromyalgia syndrome.J Pain 2012; 13(11):1068-74JP
Our aim was to assess the relationship of the Val158Met polymorphism to pain, anxiety, depression, functional ability, and pressure pain sensitivity in women with fibromyalgia (FMS). One hundred (n = 100) women with FMS diagnosed according to the American College of Rheumatology criteria participated. A numerical pain rate scale (0-10) was used to assess the intensity of pain; the Hospital Anxiety and Depression Scale was calculated to determine anxiety and depression; and functional ability was determined with the Fibromyalgia Impact Questionnaire. Further, pressure pain thresholds (PPTs) were bilaterally assessed over C5-C6 zygapophyseal joints, second metacarpal, and tibialis anterior muscles. Finally, after amplifying Val158Met polymorphisms by polymerase chain reaction, catechol-O-methyltransferase (COMT) genotype was divided into Val/Val, Val/Met, or Met/Met genotypes. Women with FMS with the Met/Met genotype exhibited higher disability (F = 11.836; P < .001), anxiety (F = 13.385; P < .001), and depression (F = 6.931; P = .002) than those with Val/Val and Val/Met genotypes. No differences for the intensity of widespread pain (F = .154; P = .857) and PPT levels over C5-C6 joints (F = 1.014; P = .336), second metacarpal (F = .216; P = .806), and tibialis anterior muscle (F = 1.179; P = .311) were found. Our results suggest that the Val158Met COMT polymorphism modulated some psychological variables but not pressure pain sensitivity in FMS, because women carrying the Met/Met genotype show higher disability, depression, and anxiety but similar PPTs than those with Val/Met or Val/Val genotypes. This study is important because it strives to understand potential genetic factors that predispose some women with FMS to exhibit a more severe phenotypic expression of the disease. Future studies are needed to elucidate potential relevance of the differences.
This study suggests that the Val158Met COMT polymorphism modulated some psychological variables but not pressure pain sensitivity in FMS because women with FMS carrying the Met/Met genotype exhibit higher disability, depression, and anxiety than but similar PPTs to those with Val/Met and Val/Val genotypes. This study provides further evidence of potential genetic factors that predispose women with FMS to exhibit the disease more severely.