FADS1 and metabolic dysfunction-associated steatotic liver disease: For example, DNA methylation in the fatty acid desaturase 1/2/3 (FADS1/2/3) gene cluster has been linked with genetic variants and desaturase activities in the human liver [119], and the expression of hepatic FADS2 mRNA and the activity of serum delta-6 desaturase (D6D) encoded by the FADS2 gene are known to increase in human NAFLD [132].