C22 Sphingomyelin is a naturally occurring form of sphingomyelin . Plasma levels of C22 sphingomyelin positively correlate with hepatic steatosis severity in patients with chronic hepatitis C virus (HCV). C22 Sphingomyelin levels are decreased in T-47D mammary epithelial cells and increased in MDA-MB-231 breast cancer cells relative to C16 sphingomyelin .