RET/PTC1 and RET/PTC3 are the most common types, accounting for >90% of all rearrangements.     ///    RET/PTC rearrangement in thyroid tumors..     ///    " Rearrangement of the RET gene, also known as RET/PTC rearrangement, is the most common genetic alteration identified to date in thyroid papillary carcinomas. "    ///    "RET/PTC has recently been found in hyalinizing trabecular adenomas of the thyroid gland, providing molecular evidence in favor of this tumor to be a variant of papillary carcinoma. "    ///    The prevalence of RET/PTC in papillary carcinomas shows significant geographic variation and is approx 35% in North America.     ///    "RET/PTC is more common in tumors in children and young adults, and in papillary carcinomas associated with radiation exposure. "    ///    "RET/PTC1 tends to be more common in tumors with typical papillary growth and microcarcinomas and to have a more benign clinical course, whereas RET/PTC3 in some populations shows a strong correlation with the solid variant of papillary carcinoma and more aggressive tumor behavior. "    ///    The occurrence of RET/PTC in Hashimoto thyroiditis and thyroid follicular adenomas and hyperplastic nodules reported in several studies has not been confirmed in other observations and remains controversial..     ///    There is some evidence that different types of RET/PTC may be associated with distinct biologic properties of papillary carcinomas.     ///    "There are at least 10 different types of RET/PTC, all resulting from the fusion of the tyrosine kinase domain of RET to the 5' portion of different genes. "