MCPH1 and microcephaly: Questioning the possible role of MCPH1 in hematopoietic development, we found that in addition to its well-known involvement in microcephaly, loss of Mcph1 leads to macrocytic dyserythropoietic anemia resulting from acytokinetic mitosis during terminal erythroid differentiation, thus preventing the production of sufficient numbers of mature red blood cells.