Abstract: Arachidonic acid is the precursor for a vast array of signaling molecules as well as a key structural component in membranes. Alteration of the concentration of arachidonic acid and its products is a valuable pharmaceutical target and in part a goal of omega 3 intake. We identified a genetic polymorphism consisting of a 22 bp insertion-deletion by means of searching the international Hapmap project, interrogating and targeted sequencing of cells, searching the 1000 genomes database, and comparing genotype to circulating PUFA. Genotyping at this locus is recommended for reducing variability in studies of PUFA-related biology and for personalized nutrition and medicine.