Individual deletion of each of the four “multicellular” genes: srfA; hdaD; DDB_G0283437, a gene which we renamed ammr1 based on its homology to the uncharacterized Alport syndrome gene Ammerc1; and DDB_G0288013; a gene which we renamed smcl1 based on its similarity to a structural maintenance of chromatin (SMC) gene, delayed the transition to multicellularity and extended the entire progression to multicellular state (Fig. 4a,b: srfA p=0.0014 and p < 0.0001; hdaD p=0.0165 and p=0.0011; ammr1 p < 0.0001 and p < 0.0001; smcl1 p < 0.0001 and p < 0.0001, respectively). The gene discussed is AMMECR1; the disease is Down syndrome.