Levels of saturated and unsaturated FA-SM and OHFA-SM in the range C14-C24 in fibroblasts, lymphocytes and erythrocytes of control subjects and in patients were quantitated by HPLC/MS-MS. A, Saturated FA-SM. B, Unsaturated FA- SM.C, Saturated OHFA-SM. D, Unsaturated OHFA-SM. E, Ratio saturated OHFA -SM/FA-SM. F. Ratio unsaturated OHFA -SM/FA- SM (mean of 2 experiments +/- SD).