FAAH and obesity due to melanocortin 4 receptor deficiency: This study is the first to document that the FAAH 385 A mutant alleles directly affect elevated plasma levels of AEA and related NAEs and suggests that using biomarkers including AEA, PEA, OEA and LEA plasma levels combined with genotyping for the minor FAAH 385 variant A allele may identify a new ECS-related obesity phenotype with a higher risk for severe obesity.