HSD17B1 encodes hydroxysteroid 17-beta dehydrogenase 1, an enzyme that plays a crucial role in steroid hormone metabolism by catalyzing the conversion of estrone to the more potent estrogen 17β-estradiol 1. The enzyme favors the reduction of estrogens and androgens and uses NADH as a cofactor. HSD17B1 has been implicated in reproductive health and disease susceptibility. Genetic variants in HSD17B1 are associated with premature ovarian insufficiency, with pathogenic mutations contributing to ovarian dysfunction 2. The gene shows altered expression in response to hormonal changes, as demonstrated in human endometrial organoids where HSD17B1 expression changes significantly during simulated menstrual cycles 3. Mouse studies reveal that Hsd17b1 knockout results in severe subfertility in females and metabolic phenotypes, though some effects may be due to disruption of the nearby Naglu gene 4. Despite its biological significance, meta-analyses of the common Ser312Gly polymorphism show no overall association with endometrial or breast cancer risk, though some ethnic-specific associations in Caucasian populations have been reported 5. The enzyme's role in estrogen biosynthesis makes it relevant for hormone-dependent conditions and reproductive disorders.