The callipyge region of ovine chromosome 18. A diagram of the callipyge region  based on GenBank accession No. AF345168 is shown. Six known transcripts are indicated along with the direction of transcription (arrows). Transcripts expressed from the paternal allele are shown as orange arrows and those expressed from the maternal allele are shown as black arrows . A blue line indicates the position of the causative mutation. Alleles with an A are wild type (+) and the mutant callipyge allele (CLPG) has a G at this position [23, 24].