RET proto-oncogene was rearranged during transformation,and so has the name.It encodes a cell membrane receptor tyrosine kinase.In recent years,the possible correlation between human diseases and Ret activation by mutation,such as rearrangement,point mutatoin,and deletion were studied.Its rearrangement with other gene fragment was frequently found in thyroid papillary carcinoma tissues.Point mutations were detected in multiple endocrine neoplasia 2 and familial medullary thyroid carcinoma.Hirshsprung syndrom may be resulted from its deletion. The structure and possible function of RET gene,its mutation effects to various human diseases were summarized.