Later Polish research tested the regulatory change directly

A 2025 study of Polish craniofacial skin investigated a small duplication within a HOXC10 intron and the higher-order regulation of the surrounding HoxC gene cluster. The researchers described a regulatory region that is normally closed in scalp tissue but active in regions such as back and tail. In the Polish scalp, its more open organization was associated with increased HoxC expression.

Experimental deletion of the duplicated sequence reduced crest-feather formation, while altered HoxC expression changed feather shapes. This provides functional evidence beyond an earlier statistical association. It explains how regional skin identity can be modified to grow different appendages in a particular body location. The work concerns molecular development; it does not establish that every crested breed has identical skull structure or that a larger crest is automatically a better conservation breeding choice.