Dihydrotestosterone (DHT) is formed when testosterone is converted by the enzyme 5-alpha reductase, and it binds to the androgen receptor far more potently than testosterone itself.

Enzyme Types

5-alpha reductase has two main isoforms: Type 1 and Type 2. Type 2 plays a particularly determinant role in androgenetic alopecia; finasteride targets this enzyme specifically, while dutasteride suppresses both types.

Genetic Inheritance

AGA is polygenic — many gene regions influence risk rather than a single gene. Having one or both parents with AGA significantly increases the likelihood in offspring. The maternally inherited androgen receptor gene (on the X chromosome) was long considered the strongest single determinant, though current research shows paternal-line genes also contribute meaningfully.

Practical takeaway: Family history — especially male relatives on the mother's side — is a useful but not definitive clue to how hair loss may progress.