Abstract 9098: The Relationship Between Linoleic Acid (LA) and Dihomo-Gamma-Linolenic Acid (DGLA) as Indicator of Delta-6-Desaturase Activity

Introduction: Low levels of dihomo-gamma-linolenic acid (DGLA) have been shown to predict total death in patients hospitalized with an acute coronary syndrome. DGLA is converted from gamma-linolenic acid (GLA) by the enzyme elongase, following a slower and rate-limiting conversion from linoleic acid (LA) to GLA by the action of delta-6-desaturase. This would suggest that DGLA levels are (strongly) associated with delta-6-desaturase activity. Furthermore, a high ratio of LA to DGLA (LA:DGLA) has been claimed to reflect reduced delta-6-desaturase activity. Hypothesis/Aim: To evaluate the relationship between LA:DGLA ratio and DGLA levels in patients with a recent myocardial infarction (MI). Methods: Baseline samples from the OMEMI (Omega-3 Fatty acids in Elderly with Myocardial Infarction) trial* in which a total of 1027 patients, aged 70 to 82 years, were included 2-8 weeks after an MI, were obtained. The total fatty acid profile was determined in serum phospholipids and relative concentrations (wt%) of LA, GLA and the LA:DGLA ratio (used as a surrogate for delta-6-desaturase activity) were evaluated across quartiles of concentrations of DGLA. Results: Levels of GLA were low compared to other n-6 fatty acids and followed the same trend as DGLA, consistent with a rapid turnover from GLA (Table 1). Furthermore, there was a steady decrease in the LA:DGLA ratio across the quartiles of DGLA, with approximately 50% lower levels in the highest compared to the lowest quartile of DGLA. Conclusion: We found a strong inverse relationship between DGLA and the LA:DGLA ratio in patients with a recent MI, indicating that the LA:DGLA ratio may serve as a measure of delta-6-desaturase activity. * Circulation 2021; 143(6): 528-39.