Congenital idiopathic megaesophagus / CIM (MCHR2 risk factor) - German Shepherd Dog

What does this test analyse?

This genetic test analyses the intron 1 MCHR2 VNTR profile in the German Shepherd Dog. The trait is known as congenital idiopathic megaesophagus, CIM and megaesophagus.

What does this mean for the dog?

CIM is a congenital oesophageal disorder in which the oesophagus does not move food and water to the stomach efficiently. Puppies may regurgitate, grow poorly, cough and have an increased risk of aspiration pneumonia. In German Shepherd Dogs, the MCHR2 VNTR profile is strongly linked to risk, and males are affected more often than females.

Practical value of this test

• Breeders can use the MCHR2 repeat profile as additional selection information in German Shepherd Dogs.
• The result helps avoid matings that are more likely to produce puppies with an unfavourable CIM risk profile.
• Because sex and other factors also influence risk, this is a risk-factor test rather than an absolute disease prediction.
• For breeding programmes, reducing the increased-risk VNTR profile is useful without unnecessarily losing breeding material.
• In lines where CIM occurs, the test gives a practical tool for discussing risk more transparently with puppy buyers and fellow breeders.

Inheritance and interpretation

This is a risk-factor profile. 2-copy/2-copy means the increased-risk 1-copy profile was not detected in this display. 1-copy/2-copy means one 1-copy risk allele is present. 1-copy/1-copy means two 1-copy risk alleles are present and CIM risk is clearly increased. The result should be read together with sex, line information and clinical context.