This did not reveal a difference in telomere lengths between the expanded SF3B1-mutant clade and polyclonal wild-type colonies, but did reveal a trend toward an increase in telomere length in the SF3B1-mutant clade (P = 0.27) but not in SF3B1-wild type cells, during the 3.6-year interval between samples (Fig. 3e,f), over which time the clinical phenotype progressed from clonal cytopenia of undetermined significance (CCUS) to MDS. The gene discussed is SF3B1; the disease is myelodysplastic syndrome.