Impact of various additional effects on the TTVs of (a) planet b, (b) planet c, and (c) planet d. Top panel: transit timing variations for a pure N-body simulation (blue); for a simulation using for all planets (orange), using for all planets (green), using for all planets (red), using (purple), using (brown), and where we only consider the general relativity (pink); and for a simulation where all effects are taken into account. Bottom panel: corresponding TTVs differences with the Newtonian N-body case.