Loss of restriction site DdeI, used for avian molecular sexing, in Oreophasis derbianus.

Molecular sexing is a rapid and safe procedure for bird sex determination. Two universal methods based on the amplification of a chromo-helicase-DNA-Binding 1 (CHD) gene region, located in both sexual chromosomes (Z and W), have been established. We found that molecular sexing of Oreophasis derbianus failed by using these two procedures. One of them is based on a restriction site located in CHD1W gene but absent in CHD1Z. The DdeI restriction site, used successfully to determine gender in several bird species, was found to be lost because of nucleotide change in O. derbianus. This change created a new restriction site, NlaIII, that was successfully applied for sexing this endangered bird.