Moreover, it seems tempting to speculate that a proportion of ATCs develop as a consequence of aberrant DNA repair mechanisms due to somatic inactivation of MMR genes in pre-existing WDTCs, in turn leading to hypermutability and the generation of multiple tumor sub-clones, of which some might give rise to an undifferentiated phenotype [Figure 1]. Here, MRC1 is linked to Ehlers-Danlos syndrome, musculocontractural type.