Premature ovarian failure (POF) is characterized by primary or secondary amenorrhea in women less than 40 years old. Two POF susceptibility regions called 'POF1' and 'POF2' have been identified by breakpoint mapping of X-autosome translocations. POF1 extends from Xq21-qter while POF2 extends from Xq13.3 to Xq21.1. This gene, POF1B, resides in the POF2 region. This gene is expressed at trace levels in mouse prenatal ovary and is barely detectable or absent from adult ovary, in human and in the mouse respectively. This gene's expression is restricted to epithelia with its highest expression in the epidermis, and oro-pharyngeal and gastro-intestinal tracts. The protein encoded by this gene binds non-muscle actin filaments. The role this gene may play in the etiology of premature ovarian failure remains to be determined.