PLEK and rheumatoid arthritis: In another study, Geiger et al. (93) also described 2 SNPs, rs9309413 and rs4775041, on PLEK (Pleckstrin) and LIPC (Hepatic Triacylglycerol Lipase) genes, which are related to sphingomyelin and PE synthesis respectively, that were associated with risk of RA in a previous study (94).