Androgenic alopecia(AGA) is the most common type of hair loss.Its pathogenesis remains unclear.Now AGA is defined as an androgen-dependent disease with characteristic multifactorial inheritance.Androgen receptor gene located on the X chromosome was first found as a susceptibility gene of AGA.Further more,the sex-determining gene located on the Y chromosome and the hairless gene on the autosome gene were also associated with AGA.Recently,scholars have revealed another two susceptibility loci on chromosome 3 q 26 and 20 p11 using genome-wide scan and fine-mapping linkage methods,which may provide further clues to the research of genetic mechanism of AGA.