Catechol-O-methyltransferase Val158Met polymorphism influences anxiety, depression, and disability, but not pressure pain sensitivity, in women with fibromyalgia syndrome.

UNLABELLED: 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. PERSPECTIVE: 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.