VetGen - Veterinary Genetic Services

Chondrodysplasia (CDPA)

Chondrodystophy and Intervertabral Disc Degeneration (CDDY and IVDD risk)

Our testing provides results for two related mutations that affect both the health and stature of many breeds of dog. Both mutations are FGF4 retrogenes, which are essentially portions of the true FGF4 gene which have been inserted into other parts of the genome.

Chondrodysplasia (CDPA)
The CDPA retrogene was first described in 2009 and was shown to be the cause of the short legs found in many, many breeds (Daschunds, Basset Hound, French Bulldog, etc.).
This mutation is dominant. Either one or two copies of the mutation result in the same short-legged phenotype. In many breeds all animals have two copies of this mutation.

A second FGF4 retrogene (CDDY) was discovered and described by the Bannasch lab in 2017 that shows an effect on both leg length and more importantly an association with premature spinal disc degeneration (IVDD). IVDD is found in many short-legged breeds and is a painful disease with a relatively high mortality rate. This mutation shows a dominant mode of inheritance with respect to IVDD. Dogs with either one or two copies of the CDDY insertion are predisposed to IVDD. With respect to leg length, the mode of inheritance is semi-dominant. Within a given breed, dogs with one copy will have shorter legs than dogs with zero copies and dogs with two copies will have even shorter legs.

Possible Result types:

CDDY

Zero copies of the CDDY mutation
One copy of the CDDY mutation- dog is short legged and at risk for IVDD
Two copies of the CDDY mutation- dog is short legged and at risk for IVDD

CDPA

Zero copies of the CDPA mutation
One copy of the CDPA mutation- dog is short legged
Two copies of the CDPA mutation- dog is short legged