In this study, we use an 18 Mb region on 10q11.2-21 containing the RET gene and its recombination partners, the H4 and NCOA4 (ELE1) genes, as a model chromosomal region frequently involved in RET/PTC rearrangements in thyroid cancer.     ///    Interphase chromosome folding determines spatial proximity of genes participating in carcinogenic RET/PTC rearrangements..     ///    RET/PTC is particularly common in tumors from children exposed to ionizing radiation. 