Transcription profiles of the Human Hox clusters.

<p>(a) Human <i>Hox</i> Cluster transcriptographs. (b) Transcriptograph of the human β-globin cluster. Note that despite an extensive transcription, the vast majority of sequences correspond to annotated genes. In 1a and 1b, annotations of genes in Refseq are depicted in red. (c) Proportion of the clusters that are primarily transcribed (d) Amount of transcription not currently annotated.