Two variants in TET2 are of note; the first, p.I1873T (rs116519313), is commonly reported as a somatic mutation (COSMIC ID = COSM41741 in haematopoietic/lymphocyte cancer x18); this patient had CM, colorectal cancer and mast cell leukaemia as distinct primary tumours and the second, an AT deletion at c.4874/4875, causing a frameshift at p.T1626, is in a patient with myeloproliferative disorder at age 65 years. Here, TET2 is linked to colorectal cancer.