Obesity may particularly predispose males to the development of PAH due toobesity-mediated adipose dysfunction resulting in altered estrogen productionand metabolism.7 OSA is common in obese men,115 in which elevated circulating estrogen levels occur because of the highexpression and activity of aromatase within adipose tissue.116,117 OSA isalso associated with the development of WHO group 3 PH. This evidence concerns the gene CYP19A1 and obesity due to melanocortin 4 receptor deficiency.