Health tests
Craniomandibular osteopathy (CMO)
- How it is done
- DNA test
- Also called
- OCM · ostéopathie cranio-mandibulaire
- What it looks for
- The SLC37A2 c.1332C>T variant associated with craniomandibular osteopathy (CMO).
- Why it matters
- The document does not state this.
- How it is done
- A DNA test for that one named variant. It is done once, the result holds for life, and it may be taken from birth onwards.
- How it is inherited
- The programme records CMO as an autosomal dominant disorder with incomplete penetrance ("autosomaal dominante aandoening met onvolledige penetrantie"). For breeding it works out like this: a free dog has two normal copies, will not develop signs from this variant and cannot pass it on; a heterozygous dog carries one variant copy and passes it to about half of its pups; a homozygous dog carries two variant copies and passes it to every pup. Only free x free earns a positive breeding advice - and a dog accepted as free by descent ("Vrij door afstamming") counts as free here, without a test of its own - every other combination is a breeding ban (fokverbod).
- For the breed
- Seen in the breed
- What the results mean
-
- Vrij (free) — Two normal copies of the gene. The dog will not develop symptoms from the variant tested and cannot pass the variant to its offspring.
- Heterozygote lijder (heterozygous sufferer) — One normal and one variant copy. The programme states that such a dog will develop symptoms from the variant and has a 50% chance of passing it to each pup, which will in turn develop symptoms. The same document's breed sheet records incomplete penetrance instead, and the disagreement is set out further down this page.
- Homozygoot lijder (homozygous sufferer) — Two variant copies. The programme states that such a dog will develop symptoms from the variant and passes it to all of its offspring, which will in turn develop symptoms. The same document's breed sheet records incomplete penetrance instead, and the disagreement is set out further down this page.
- Vrij door afstamming (free by descent) — Not tested itself. Both parents were DNA-tested free and parentage was verified, so the dog is accepted as free without its own test.
- Ongetest (not tested) — No DNA test was carried out.
The sources disagree
Whether a dog carrying the variant will certainly develop the disease.
-
According to
Flemish breeding programme, breed sheet
Autosomal dominant with incomplete penetrance ("autosomaal dominante aandoening met onvolledige penetrantie").
If this is right: Carrying the variant raises the risk without making illness certain.
-
According to
Flemish breeding programme, genotype glossary in the same document
A heterozygous or homozygous dog "zal symptomen ontwikkelen" — will develop symptoms.
If this is right: Read literally, every dog with a copy is a future patient, which contradicts the incomplete penetrance stated on the same document's breed sheet. Which of the two a club applies is worth asking before planning a mating.
-
According to
OMIA 002244-9615, quoting Hytönen et al. (2016)
Dogs homozygous for the variant were found with no reported clinical signs, and heterozygous dogs were found that had developed CMO.
If this is right: An affected result does not reliably predict that an individual dog will fall ill. The passage says nothing about dogs that test clear, so nothing here weakens a clear result.
This site does not settle it. Both positions are shown with who holds them, because choosing one would mean overruling either a government decree or the laboratory that runs the test. Ask your own club which reading it applies.
Source: Fokprogramma Cairn Terrier (Vlaamse overheid), Rasfiche > Verplichte prestatieonderzoeken: "Aandoening: Craniomandibulaire osteopathie (CMO)"; and Fokadvies > Fokadvies per prestatieonderzoek: "Craniomandibulaire osteopathie (CMO) via DNA test", with its genotype glossary and the "Vrij door afstamming" clause. (Document footer: "Dit document werd het laatste bijgewerkt op: 18/07/2026" (PDF rendered 09-08-2026)) — https://assets.vlaanderen.be/image/upload/v1747394527/repositories-prd/DWZ_fokprogramma_Cairn_Terrier_fkil2q.pdf · Explanations checked: 2026-08-11
Explanations checked: 11 August 2026