Fig. 2

The mQTL is particularly pronounced in females with knee OA. Data was stratified into knee (A), female (B) and female knee (C) strata. The methylation data is in the form of β-values ranging from 0 (no methylation) to 1 (complete methylation) and expressed as a percentage. Due to their low number (< 3) in each stratum, minor allele homozygotes (CC) were combined with heterozygotes (TC). There were no minor allele homozygotes in the female knee strata. In the violin plots, solid and dashed horizontal lines represent the median and interquartile range. Difference in numbers (n) due to variable number of patient samples per CpG passing quality control, with numbers in parentheses the number of patients per genotype (TT, TC, CC). P-values calculated by linear regression. * = P < 0.05; ** = P < 0.01; *** = P < 0.001; **** = P < 0.0001; ns = not significant (P > 0.05)