Cover: Confocal image showing a coronal slice from a mouse cortex at embryonic day 14. Cell nuclei are stained with DAPI (blue), cells that have undergone one cell division are labelled with BrdU (green), and cortical progenitors are labelled with Sox9 (red). Sterling & Duncan et al. found that a human patient with a heterozygous mutation in MPP5 was born with microcephaly. A conditional, heterozygous deletion of MPP5 using Nestin-Cre in mice also resulted in a microcephaly phenotype due to diminution of proliferating cortical progenitors and compromised cell survival, supporting the pathogenic effects of de novo mutations of MPP5.