Manhattan plot for a multiple regression on MWD with additional non-genetic variables. The vertical axis represents the common logarithm of the P value, numbers on the horizontal axis represent the chromosome. Signals below the genome-wide significance threshold of 10â08 are represented in green. In addition to age, height and weight, Factor IX levels, smoking status, ALT, urea levels, haemoglobin count and basophils count were used as covariates in the regression on warfarin mean dose. (PNG 1601 kb