An inverse correlation exists between the occurrence of IHD and levels of S1P and DH-S1P in HDL-containing fractions from CCHS subject serum. S1P (A) DH-S1P (B) and C24.1 ceramide (C) levels were measured by blinded LC-MS-MS analysis of 55 HDL-containing preparations from CCHS individuals with high HDL-C and no evidence of IHD, 53 samples from individuals with high HDL-C and evidence of IHD, 54 samples from individuals with low HDL-C and no evidence of IHD and 42 samples from individuals with low HDL-C and evidence of IHD. In D-F, levels of S1P and DH-S1P in HDL-containing serum fractions from CCHS individuals with and without IHD are assessed relative to apoA-I content. Levels of apoA-I in samples were quantified by immunoturbidometric assay using a Cobas Fara analyzer. Indicated p-values are derived from a Tukey's comparison following a one-way ANOVA test conducted at level of significance 0.05. Data are presented in box-and-whisker diagrams. For the box-and-whisker diagrams, the boxes correspond to the interquartile range (IQR). The horizontal bar within the box is drawn at the height of the median. The whiskers indicate the range of the data within 1.5 X IQR with outliers indicated as circles.