Glenbern Golden Retrievers & Bernese Mountain Dogs

DNA Testing-Mode Of Inheritance

 

 There are a number of diseases that are inherited in an autosomal recessive fashion for which we now have a a DNA test to determine each dog's health status.  An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.

Dogs will fall into three categories:

CLEAR: Dog has inherited two 'Normal' genes. 'Clear' dogs can safely be bred to any dog.

CARRIERS: Dog has inherited one 'Clear' gene and one mutant gene. 'Carrier' dogs are NOT at risk to develop the disease, but should only be bred to 'Clear' dogs.

AFFECTED: Dog has inherited two mutant genes. Dogs are at risk for developing disease at some point in their lifetime. An 'Affected' dog can be bred to a 'Clear' dog; offspring from such a breeding would all be 'Carriers', but would not develop the disease.

Many dogs are 'Clear by Parentage', meaning both of their parents have two 'Normal' copies of a gene and therefore can only pass on 'Normal' genes to their offspring. 

 
Clear
Carrier Affected


Clear


All=Clear 50%=Clear

50%=Carriers

All=Carriers


Carrier

 

50%=Clear

50%=Carriers

25%=Clear

50%=Carriers

25%=Affected

50%=Carriers

50%=Affected



Affected

 

All=Carriers 50%=Carriers

50%=Affected

All=Affected

*It is important never to breed two carrier dogs, because on average 25% of the pups could be affected.  One parent should always be clear/normal for the disease



Autosomal Recessive Diseases Affecting Golden Retrievers:

Progressive Retinal Atrophy (PRA): is a degeneration of the layers of the retina that are responsible for vision. The disease is progressive, eventually resulting in blindness. There are three types of PRA (PRA1, PRA2, PRA_prcd) for which a DNA test is available.

Icthyosis: is a mutation that prevents the outer layer of the epidermis from forming properly, resulting in skin that becomes darkened and thick, with excessive flaking. Evidence of the disease may be detected when the dog is still a puppy, and as such is often referred to as 'puppy dandruff'. 


Genetics Basics-Modes Of Inheritance