COMT and obesity due to melanocortin 4 receptor deficiency: Recently, Hegazy et al. [232] reported that high fat diet induced obesity was associated with reduced catechol O-methyltransferase (COMT) expression with a concomitant increase in plasma catecholamines as well as metabolic effects such as glucose intolerance, derangement of the lipid profile, and increased systolic blood pressure.