SRD5A1 encodes steroid 5α-reductase type 1, a membrane-bound enzyme catalyzing the conversion of testosterone to 5α-dihydrotestosterone (DHT) and progesterone/corticosterone to their 5α-reduced metabolites 1. This enzymatic activity is essential for amplifying androgen receptor signaling in target tissues 1. The enzyme contains seven transmembrane helices with a conserved catalytic domain, and notably, human SRD5A1 mRNA undergoes triple-frame translation producing multiple proteoforms, a feature specific to primates 2. In reproductive physiology, SRD5A1 expression is dynamically regulated during reproductive phases and responds to gonadotropin-releasing hormone stimulation 3. During human labor, SRD5A1 expression decreases significantly in chorioamniotic membranes, indicating tissue-specific roles in progesterone metabolism 4. Clinically, SRD5A1 polymorphisms associate with impaired glucose homeostasis in males, with the rs1691053 CC genotype showing increased odds for impaired fasting glucose in interaction with testosterone levels 5. In prostate cancer, SRD5A1 promotes disease progression by elevating intracellular DHT and enhancing androgen receptor expression; combined inhibition of SRD5A1 and BRD4 shows enhanced therapeutic potential 6. Additionally, targeting SRD5A1 suppression induces autophagy in colorectal cancer through PI3K/AKT pathway inhibition 7.