INHA (A-inhibin subunit precursor, inhibin alpha subunit ), also called inhibin (alpha) ,which is located on chromosome 2q33-q36. Inhibin is a gonadal protein that preferentially suppresses the secretion of pituitary follicle-stimulating hormone (FSH). Inhibin comprises of two subunits,Inhibin A and B. Inhibin has been shown to regulate gonadal stromal cell proliferation negatively and to have tumor suppressor activity. In addition, serum levels of inhibin have been shown to reflect the size of granulosa cell tumors and can therefore be used as a marker for primary as well as recurrent disease. In addition to their role in endocrine feedback in the reproductive sytem, inhibins subserve local regulatory roles in numerous extragonadal tissues, including brain, adrenal,bone marrow, placenta, and most notably anterior pituitary. Inhibin alpha subunit gene expression is down regulated in human prostate cancer, suggesting a tumor suppressive role.