Extended report Depression and sleep were independently associated with CWP (data not shown). Signiﬁcant associations with CWP were adjusted for depression and/or sleep if there was evidence of association between the SNP and depression and/or sleep, to determine if the associations were occurring independently of these comorbid factors. Interactions between SNPs (associated with CWP) and depression and sleep were also tested to deter- mine if they were moderating the relationship between the SNP and CWP. RESULTS Participants DNA samples were obtained from 1189 participants with pain data at all time points. Samples from 195 (16%) participants were not successfully genotyped for 90% of the SNPs and were excluded from the analysis. The characteristics of the resulting Table 1 Participant characteristics Total population Cases Controls CWP analysis 164 172 52.6 (50.3 to 53.9) 48.5 (46.4 to 51.6) 66 57 5 (4 to 6) 2 (1 to 2) 11 (10 to 13) 3 (2 to 4) n 994 Median age (95% CI) 50.9 (49.8 to 52.0) % Female 58 Median depression 3 (2 to 3) score (95% CI) Median sleep score 5 (5 to 5) (95% CI) CWP, chronic widespread pain. Table 2 Signiﬁcant associations with the maximum number of pain sites in participants reporting pain Gene SERPINA6 SNP rs941601 rs11627241 rs1998056 rs746530 rs3769671 rs1875999 SNP, single nucleotide polymorphism. Genotype CC CT TT CC and CT TT CC and CG GG GG GA AA AA AC and CC TT TC and CC n 604 202 16 772 50 671 149 352 360 101 740 65 373 444 Proportional change (95% CI) Reference 1.16 (1.04 to 1.28) 1.34 (1.09 to 1.64) Reference 1.27 (1.03 to 1.57) Reference 1.18 (1.03 to 1.34) Reference 1.10 (1.02 to 1.19) 1.21 (1.05 to 1.41) Reference 0.81 (0.67 to 0.99) Reference 1.12 (1.01 to 1.24) p Value – 0.006 0.006 – 0.026 – 0.017 – 0.011 0.011 – 0.040 – 0.036 994 participants are given in table 1. The nested case-control study of CWP consisted of 164 cases and 172 controls. HAD depression and sleep quality scores in the cases were signiﬁ- cantly (Mann–Whitney U test, p<0.001) higher than in the con- trols (table 1). Genotyping Of the 88 SNPs selected, 75 were successfully genotyped and in HWE (p>0.01). Coverage of HapMap SNPs (r2<0.8) was 100% for POMC, 92% for CRHR1 and MC2R, 87% for SERPINA6, 84% for NR3C1, 67% for CRH and 60% for CRHBP. Total number of pain sites Four SNPs spanning 5’ to intron 4 of SERPINA6 showed asso- ciation with the maximum number of pain sites in participants reporting pain. rs941601 and rs746530 both showed a signiﬁcant trend for an increase in the maximum number of pain sites, in participants reporting pain, with the number of copies of the minor allele. A signiﬁcant increase in the maximum number of pain sites was observed in participants with two copies of the minor allele (recessive effect) for rs11627241 and rs1998056 com- pared to participants with zero copies or one copy (table 2). In participants reporting pain, having one or two copies of the minor allele of rs3769371 in POMC was associated with a reduc- tion in the maximum number of pain sites compared to having zero copies (dominant effect). Conversely, rs1875999 in CRHBP was associated with an increased maximum number of pain sites in participants with one or two copies of the minor allele com- pared to participants with zero copies (table 2) and also showed evidence of association with an increased likelihood of depres- sion (proportional change=1.10, 95% CI 1.00 to 1.20, p=0.047 for each copy of the minor allele) and poor sleep quality (propor- tional change=1.15, 95% CI 1.06 to 1.25, p=0.001 for each copy of the minor allele in participants reporting sleep problems (sleep quality score ≥1)). Adjusting the association between the maxi- mum number of pain sites and rs1875999 for HAD depression score and sleep quality rendered the association non-signiﬁcant (proportional change=1.01, 95% CI 0.91 to 1.11, p=0.860). There was no evidence of interaction between the SNPs, associ- ated with pain, and depression or sleep on the maximum number of pain sites. There was also no evidence of association between the maximum number of pain sites in participants reporting pain and SNPs genotyped in CRH, CRHR1, MC2R and NR3C1. CWP Two SNPs in SERPINA6 were signiﬁcantly associated with CWP. Rs941601 and rs8022616 showed a signiﬁcant trend for increasing and decreasing the odds of having CWP with the number of cop- ies of the minor allele, respectively (table 3). These two SNPs are POMC CRHBP 558 Table 3 Signiﬁcant associations with CWP Gene SERPINA6 SNP rs941601 rs8022616 MC2R rs11661134 CWP, chronic widespread pain; SNP, single nucleotide polymorphism. Genotype CC CT TT AA AG GG GG AG and AA n (%) Cases 117 (71) 43 (26) 4 (3) 142 (87) 20 (12) 2 (1) 132 (84) 26 (16) Controls 138 (81) 31 (18) 2 (1) 131 (77) 36 (21) 3 (2) 158 (92) 14 (8) OR (95% CI) Reference 1.61 (1.02 to 2.55) 2.59 (1.03 to 6.52) Reference 0.58 (0.34 to 0.97) 0.33 (0.12 to 0.93) Reference 2.22 (1.12 to 4.43) p Value – 0.040 0.040 – 0.037 0.037 – 0.023 Ann Rheum Dis 2010;69:556–560. doi:10.1136/ard.2009.116137