Adjustment on possible confounders was performed with the multivariate Cox proportional hazards model using the same adjustments as previously.
The ChIP assay kit (Upstate Biotechnology, Waltham, MA, USA) was utilised according to the manufacturer's instructions with minor adjustments as previously described (Yong et al, 2012).
Statistical evaluation for multiple array comparison was performed using Lavene-test followed by t-test (parametric) or by Mann-Whitney U test (non-parametric), with significance level correction according to the number of compared genes (Bonferroni adjustment) as described previously [ 28].
Linear regression models were used to assess the association between continuous traits and genotypes (assuming an additive model), with adjustment for covariates as previously described [ 7].
All patients received folic acid supplements and their liver enzymes and blood count tests were monitored according to the local guidelines, with dose adjustments if needed, as previously described [ 16].
d) Network synchrony estimated by two measures - Burstiness Index (BI, calculated according to Wagenaar and colleagues [ 70 ], with some adjustments of parameters as previously described [ 35 ]) and Sync Ratio, calculated at half-hour intervals for previously published experiments [ 35 ] in which CCh was used to elevate cholinergic tone.
Multivariate linear regression between serum urate levels and each of the known dietary trigger foods (using the same adjustments as stated previously) was also performed for all individuals and the male and female only subsets (Additional file 5: Table S4).
Non-biological signal variation due to possible array differences or hybridisation treatments were minimised by normalisation of the raw data using the Robust Multi-array Average (RMA) method [ 42, 43] with adjustments as detailed previously [ 44, 45].
No participants reported pain during the testing, and all participants were able to complete the full protocol with some minor adjustments to the normalization exercises as previously discussed.
As previously mentioned, the adjustment steps, which cannot be performed due to the restriction of Equation (8), are scheduled and performed asynchronously.
