Since the cybrids we worked with have an osteosarcoma nuclear background (143B), and ESR1 was in the list of hypermethylated genes in high-heteroplasmy cells (Fig. 5A) we looked in detail at the differential methylation of the ESR1 locus (Fig. 5B) and compared the ESR1 expression, namely the estrogen receptor 1 protein between the 13H and 13L lines (Fig. 5C). Here, ESR1 is linked to osteosarcoma.