Lancashire Heeler DNA screening

Distinguishing between clear, carrier and affected dogs

Clear dogs have no copies of the mutant gene responsible for the condition and will neither develop the condition nor pass the gene on to their offspring.

Carrier dogs have one copy of the normal gene and one copy of the mutant gene; they will not develop the condition, but will pass a mutant gene on to approximately half of their offspring.

Affected dogs have two copies of the mutant gene that causes the condition and will develop the disease.

Linkage tests

Most DNA tests look for a specific gene that causes a particular condition. Sometimes scientists can’t find the gene responsible for the disease, but they can find sections of DNA that often appear to be somehow linked to the undiscovered gene. DNA tests that look for this linked genetic material are called linkage tests.

Linkage tests can be a very accurate way to know if your dog is clear, a carrier or affected for a particular genetic condition, but they may not be quite as accurate as the DNA tests that look for the disease causing genes themselves.

Linkage tests and hereditary status

Due to the reduced accuracy of some linkage tests, any progeny from dogs tested using a linkage test are unable to be assigned a hereditary status on our database or website (i.e. puppies from two dogs both found to be clear of a condition can not be said to be hereditarily clear).

Primary Lens Luxation (PLL)




Collie Eye Anomaly/Choroidal Hypoplasia (CEA/CH)


Collie Eye Anomaly/Choroidal Hypoplasia (CEA/CH) - LINKAGE


Related Topics

Dna Screening Schemes DNA Screening
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