Chondrodystrophy (CDDY) with risk of IVDD and Chondrodysplasia (CDPA) DNA test at Canine Genetic Testing

Chondrodystrophy (CDDY) with risk of Intervertebral Disc Disease and Chondrodysplasia (CDPA)

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Find out if your dog has Chondrodystrophy (CDDY) with risk of IVDD or Chondrodysplasia (CDPA) at CAGT.

CODE IVDD-CD
Categories , ,
Turnaround 1-2 weeks
Breed(s) , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
OMIA No entry
Aliases , ,

Overview

Two separate genetic variants are detected with this test, and will be reported separately.

  1. Chondrodystrophy (CDDY) with risk of IVDD associated with the FGF4-12 retrogene insertion.
  2. Chondrodysplasia (CDPA) associated with the FGF4 -18 retrogene insertion

Chondrodystrophy (CDDY) with risk of IVDD

Chondrodystrophy (CDDY) in dogs is defined by dysplastic (abnormal), shorted long bones (short legs) and premature degeneration and calcification of intervertebral discs. Chondrodystrophic breeds are prone to a type of disc degeneration called chondroid metaplasia, where the discs become hardened and less able to flex with movement and therefore more prone to bulging or rupture i.e. Intervertebral Disk Disease (IVDD). The calcified inner disc material also puts pressure on the spinal cord, causing pain and damage to the nerves running through the spinal cord. Dogs may suffer from severe pain, inability to urinate or defecate, paralysis and even death. Many affected dogs are treated by surgically removing the prolapsed disc.

A partial copy of the FGF4 gene has been inserted (FGF4-12, a retrogene insertion) on chromosome 12 and is associated with CDDY. Evidence that suggests that any dog with one or two copies of FGF4-12 will be affected with CDDY, will have short legs and will be predisposed to IVDD. However, not all dogs with FGF4-12 will go on to develop IVDD.

Chondrodysplasia (CDPA)

Chondrodysplasia (CDPA) is shortened long bones, resulting in dogs with short legs.

A partial copy of the FGF4 gene has been inserted (FGF4-18, a retrogene insertion) on chromosome 18 and is associated with CDPA. Evidence that suggests that any dog with one or two copies of FGF4-18 will have short legs. Unlike CDDY, CDPA is not associated with any disease.

Autosomal Dominant

Chondrodystrophy (CDDY) with risk of IVDD

The FGF4-12 retrogene insertion that causes Chondrodystrophy (CDDY) with risk of IVDD in dogs is autosomal dominant with incomplete penetrance. This means that dogs that carry one or two copies of the retrogene insertion (heterozygotes and homozygotes respectively) will have Chondrodystrophy and will be at increased risk of developing IVDD during their lives. They will also pass the mutation on to all (for homozygotes) or half (for heterozygotes) of any offspring they have.

In some breeds the prevalence of the FGF4-12 retrogene insertion is too high to be able to safely breed away from the variant without adversely affecting the overall genetic health of the breed. Each breed should make their own decisions about whether they should breed away from the variant based on reliable estimates of the allele frequency. Only if safe to do so, heterozygotes (“carriers”) should not be bred from, even if they are mated to a dog that has also been tested and is clear of the FGF4-12 retrogene insertion (i.e. carry no copies of the mutation). If a heterozygote is mated to a clear dog approximately half of the resulting puppies will also be heterozygous and will develop Chondrodystrophy (CDDY) with risk of IVDD caused by the FGF4-12 mutation during their lifetime.

Chondrodysplasia (CDPA)

The insertion of the FGF4 retrogene into chromosome 18 that causes Chondrodysplasia (CDPA) in dog is autosomal dominant. This means that dogs that carry one or two copies of the mutation (heterozygotes and homozygotes respectively) will have Chondrodysplasia (short legs). They will also pass the mutation on to all (for homozygotes) or about half (for heterozygotes) of any offspring they have.

Gene FGF4
Variant Retrogene insertions
Assay Type Variant Specific
Inheritance Autosomal Dominant
Severity Low-Moderate: Affected animals experience discomfort or dysfunction of some kind, but life expectancy is not affected.
Publication

Parker HG, BM VonHoldt, P Quignon et al. (2009) An expressed fgf4 retrogene is associated with breed-defining chondrodysplasia in domestic dogs. Science. 325(5943): 995-998 . DOI: 10.1126/science.1173275.

Brown EA, PJ Dickinson, T Mansour et al. (2017) FGF4 retrogene on CFA12 is responsible for chondrodystrophy and intervertebral disc disease in dogs. Proceedings of the National Academy of Sciences of the United States of America. 114(43): 11476-11481 . DOI: 10.1073/pnas.1709082114.

Batcher K, P Dickinson, M Giuffrida et al. (2019) Phenotypic Effects of FGF4 Retrogenes on Intervertebral Disc Disease in Dogs. Genes (Basel). 10(6): . DOI: 10.3390/genes10060435.

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