ATRX and osteosarcoma: A European WES and targeted sequencing study on 1244 patients with osteosarcoma led to the identification of likely pathogenic (c.124G>T, p.Gln376Arg, c.205C>T, D224N) and pathogenic variants (c.1851_1852delTA) in POT1, among a few unexpected genes (CDKN2A, MEN1, VHL, APC, MSH2, ATRX), other than in TP53.