Haplotype diversity across breeds has been assessed by
Dunner et al. (2003) who have shown that, of the six
breeds to display the nt821(del11) mutation, only the
Belgian Blue breed seems to be genetically homogeneous.
It was determined that the European muscular hypertrophy,
defined as that caused by the nt821(del11) mutation,
came about from different waves from northern
European breeds whose purpose was mainly for milk. It
was also surmised by Dunner et al. (2003) that some of
the other mutations arose in single breeds, and were thus
highly selected, and as such have not evolved in other
populations to any notable extent.