Progressive Retinal Atrophy or PRA

4th February 2011 the AHT announced that the research into the gene for late onset PRA in the Gordon Setter had been discovered and the following is that announcement.

Identification of Mutation for Progressive Retinal Atrophy in the Gordon Setter

A mutation responsible for the development of Progressive Retinal Atrophy (PRA) in the Gordon Setter has been identified by geneticists working in the Kennel Club Genetics Centre at the Animal Health Trust. 

PRA is a well-recognised inherited condition that many breeds of dog are predisposed to.  The condition is characterised by bilateral degeneration of the retina which causes progressive vision loss that culminates in total blindness.  There is no treatment for PRA.

Owners report that their affected dogs develop night blindness in the first instance, which is indicative of a rod-cone degeneration, so we have termed this mutation rcd4 (for rod-cone degeneration 4) to distinguish it from other, previously described, forms of rod-cone degeneration. 

The mutation is recessive and 19 out of the 21 Gordon Setters in our study that had clinical signs of PRA were homozygous (carried two copies) for this mutation, indicating it is the major cause of PRA in the breed. Two dogs in our study had PRA but did not carry the rcd4 mutation, indicating there might be another, genetically distinct, rarer form of PRA segregating in this breed. 

 The Animal Health Trust has developed a DNA test for the rcd4 mutation that will be available from Monday 14th March, 2011.  DNA test kits will be available to order online, via our website (www.aht.org.uk) from March 14th.  The price of the test will be 48 per sample, which includes VAT. 

 The research that led to identification of the rcd4 mutation was funded by many different organisations, including the Kennel Club Charitable Trust, the British Gordon Setter Club, the Gordon Setter Field Trial Society, the Gordon Setter Association, the Gordon Setter Club of Scotland and the LUPA project (www.eurolupa.org.uk) as well as several individuals who have also contributed significantly.  The AHT would like to thank sincerely all the organisations and individuals who donated funds to help support the research as well as all the owners who contributed DNA and information from their dogs.

 

Table showing all the combinations of outcomes for different matings

Parents

 

Progeny (Offspring)

 

Each puppy has a ...

PP x PP

Normal x Normal

x

=

 

100% chance of being normal

PP x Pp

Normal x Carrier

x

=

 

50% chance of being normal
50% chance of being a carrier

PP x pp

Normal x Affected

x

=

 

100% chance of being a carrier

Pp x Pp

Carrier x Carrier

x

=

 

25% chance of being normal
50% chance of being a carrier
25% chance of being affected

Pp x pp

Carrier x Affected

x

=

 

50% chance of being a carrier
50% chance of being affected

pp x pp

Affected x Affected

x

=

 

100% chance of being affected