Clonal RET /PTC rearrangements occur in about 20% of PTC and are specific for this tumor Non-clonal RET /PTC rearrangements have been found not only in PTC but also in 10–45% of thyroid adenomas and other non-neoplastic thyroid lesions and Hashimoto’s thyroiditis [27]. The gene discussed is RET; the disease is Hashimoto thyroiditis.