Analysis of kcnq4 genomic structures. A. Schematic representation of zebrafish genomic clone containing kcnq4-related sequences - these have not at the time of the publication of this work been mapped to a chromosome. B. Partial structure of the Chr 19 Kcnq4 genomic clone. Only the first three exons have been identified. Blue boxes indicate active exons, while white boxes indicate silent exons. A yellow box shows the 5′ untranslated region of Kcnq4 from chromosome 19. Arrows indicate the location of primers used for mRNA detection across the largest number of exons.