Heritability of mutation. (A) Sibling recurrence risk estimation for DNMT3A and TET2 using unrelated ages-matched as controls. (B) Example of a familial cluster of acquired mutations in TET2. The pedigree shows a sib-ship of 7, with 4 harboring different TET2 somatic mutations and 1 a DNMT3A. *, nonsense mutation; fs, frameshift mutation; Ks, sibling recurrence risk; λs, recurrence-risk ratio of disease in siblings.