FGF4

So chondrodysplasia versus chondrodystrophy.

Um, and they, they phenotyped dogs by, you know, dogs with super short legs versus dogs without short legs, and they found this variant on chromosome 18, which was an FGF4 retrogene.

Um, and later on when we identified a second FGF4 retrogene that was responsible for chondrodystrophy, it was really great that the Ostrander group had used the term chondrodysplasia because the, the chondrodystrophy name had been given to these dog breeds in the 1950s, so it wasn't really up to us to, to change it.

So it actually turned out all okay as far as the way we refer to these things.

Um, I'll just say that there are other dwarfism phenotypes that segregate within breeds, and the, probably the more correct term for those is skeletal dysplasia.

This mutation is that there's an insertion of an entire gene on a chromosome where it doesn't belong.

And unfortunately, it's inserted somewhere that pushes its expression in the intervertebral disc where it is not normally expressed.

So there's 20 times as much expression of FGF4 in the intervertebral discs of chondrodystrophic dogs compared to non-chondrodystrophic dogs.