AOC1 and fibromyalgia: Consequently, the present study aimed to determine the prevalence of genetic DAO deficiency associated with any of the four variants in the AOC1 gene, namely, p.Thr16Met (rs10156191), p.Ser332Phe (rs1049742), p.His664Asp (rs1049793), and c.691G > T (rs2052129), in Spanish women with fibromyalgia, and compare the obtained distribution of allelic and genotypic frequencies with those of European population samples in Hardy–Weinberg Equilibrium (HWE) extracted from the Allele Frequency Aggregator (ALFA) database [21].