The second isoenzyme of 5α reductase is deficient in the classic intersex condition ( pseudovaginal perineoscrotal hypospadias ), or 5α-reductase deficiency . It was first discovered in indigenous cultures of Papua, New Guinea , where children were born with feminine genitalia in the absence of endogenous DHT during pregnancy, but with the surge of testosterone during adolescence, changed to males at puberty. Because of this change at puberty, the condition is also sometimes called " guevedoche ."  There is a range of external appearance that has been described of external genitalia at birth, with varying degrees of virilization.
Dutasteride, however, is a so-called dual inhibitor with both 5α-R1 and 5α-R2 inhibition. IC50 for 5α-R1 is 7 nM but 6 nM for 5α-R2. As mentioned above, it reduces DHT > 90% overall, or precisely % and for intraprostatic DHT the reduction is 97-99%. Dutasteride has also been found to inhibit 5α-R3, in vitro, with IC50= nM.  The 2,5-difluorophenyl side chain on the D-ring of the compound shows significant lipophilic features and as increased lipophilicity enhances the potency of the compounds binding at pocket site, its potency is much greater than of finasteride.