Chromosomal distribution of human DUX4- like genes and mouse 'chromosome 10' Dux Genes. (A) Twenty-three human DUX4-like sequences include four loci with predicted introns interrupting the coding sequence (orange arrows) and nineteen intronless sequences (grey arrows), most clustering on chromosomes 4, 10 and Y. One putative intron-containing locus at chromosome 10q26.3 is disrupted by a translocation or is the remnants of two loci. (B) The Dux gene on mouse chromosome 10 has been duplicated in tandem to generate three loci. Orientation of arrows indicates direction of transcription; small arrowheads indicate putative introns.