Participants were genotyped for a functional non-synonymous single-nucleotide polymorphism (C385A; rs324420), resulting in the conversion of a conserved proline residue to threonine (P129T) in the amino-acid sequence of FAAH.43 In human lymphocytes, FAAH 385A, with an allele frequency of ∼25% in populations of Western European ancestry, is associated with normal catalytic properties but reduced cellular expression of FAAH, possibly through enhanced sensitivity to proteolytic degradation43,44 The C385A is the most common polymorphism in FAAH.45 The 385A variant has previously been associated with obesity and reward-related pathologies, including street drug use and problem drug/alcohol abuse43,45 In addition, we previously linked the 385A allele in the current sample with relatively diminished threat-related reactivity of the amygdala.46
