Estradiol 17-beta-dehydrogenase 12 is an enzyme that in humans is encoded by the HSD17B12 gene.

This gene encodes a very important 17beta-hydroxysteroid dehydrogenase (17beta-HSD) that converts estrone into estradiol in ovarian tissue. This enzyme is also involved in fatty acid elongation. [provided by RefSeq, Oct 2011].
Function: Catalyzes the transformation of estrone (E1) into estradiol (E2), suggesting a central role in estrogen formation. Its strong expression in ovary and mammary gland suggest that it may constitute the major enzyme responsible for the conversion of E1 to E2 in women. Also has 3-ketoacyl-CoA reductase activity, reducing both long chain 3-ketoacyl-CoAs and long chain fatty acyl-CoAs, suggesting a role in long fatty acid elongation.