SF3B1 and myelodysplastic syndrome: Regarding those cases with SF3B1 mutation and del(5q), they argued that, although genetic ontogeny of these myelodysplastic clones might inform the classification process and determine whether a case with concomitant del(5q) and SF3B1 mutation should be more appropriately classified as MDS del(5q) or MDS with mutated SF3B1, in many cases, clonal hierarchy cannot be easily solved in the clinical practice.