RECQL4 and osteosarcoma: RTS II, on the other hand, is caused by autosomal recessive variants in the RECQL4 gene located at the 8q24.3 locus (Wang et al., 2003; Mo et al., 2018; Lu et al., 2020) and is characterized by poikiloderma, congenital bone defects, and an increased risk of osteosarcoma and skin cancers, squamous and basal cell carcinomas (Lu et al., 2020).