In 1989, Arnold and colleagues found a genetic rearrangement in a parathyroid adenoma, this rearrangement, inv (11) (p15; q13), positions the 5′ PTH gene regulatory region (located in 11p15) adjacent to the CCDN1 gene leading to the overexpression of cyclin D1 protein [31]. Here, CCND1 is linked to parathyroid gland adenoma.