C4B and cyclic hematopoiesis: In light of the fact that PPM1D-CH and splicing factor-CH are prevalent amongst both TBD patients and older people with lower LTL-PRS, we hypothesized that somatic mutations in the TERT gene promoter (TERTp), which drive the most common form of CH in TBD patients23, may also be enriched in people with polygenic short telomeres.