Indeed, FF from small (5–8 mm diameter) PCOS or healthy follicles, pretreated with charcoal to eliminate steroids, increase GC aromatase conversion activity, at least partially through increasing substrate affinity (Kd of [11C] vorozole lower in charcoal-pretreated FF compared to untreated FF). This evidence concerns the gene CYP19A1 and polycystic ovary syndrome.