Mutations in arx-2 , arx-4 , arx-7 , and erm-1. The structures of the arx-2, arx-4, arx-7, and erm-1 genes are shown. Filled boxes represent exons, arrows represent translational start sites in putative cDNAs, and 5' is to the left. The extent of deletions in each of the genes is shown below the structure. The arx-7(ok1118) deletion extends into the gene to the 3' of arx-7.