GLEN OF IMAAL TERRIER : Progressive Retinal Atrophy
From the first diagnosis to DNA testing
Bregorrey Glens GLEN OF IMAAL TERRIER What is PRA? : What is PRA? Generalised progressive retinal atrophy (GPRA or PRA) is an “umbrella term” for a number of canine inherited eye diseases that cause blindness.
PRA causes degeneration (dying off) of specialised photoreceptor cells – cones (daytime vision) and rods (night and dim light vision) – in the retina, leading to gradual deterioration in eyesight and eventual loss of vision.
Ophthalmoscopic (eye) examination provides evidence that Glen PRA is late onset. Retinal degeneration can begin in some affected Glens at around 2 years of age, but other affected Glens may not show any signs of retinal degeneration until they reach 7+ years of age.
As with age of onset, progression of the disease can also be quite variable, with some affected Glens losing their sight completely, but other affected Glens losing their sight so slowly that they never go completely blind during their lifetime. History of PRA and the Glen : History of PRA and the Glen Mid 1990’s – the first diagnosis of PRA in a Glen was made, by ophthalmoscopic examination.
Late 1990’s – research to find the DNA mutation for Glen PRA began at Cornell University, USA under the leadership of Dr Greg Acland and principal researcher, Orly Goldstein.
Late 2006 – another research project at Ruhr University, Bochum, Germany, under the leadership of Professor Joerg Epplen and principal researcher, Regina Kropatsch, commenced.
June 2010 – both research teams announced that they had identified the same gene mutation (ADAM9 deletion) that causes cone-rod dystrophy (GPRA-crd3) in the Glen of Imaal Terrier. Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 Mode of inheritance of GPRA-crd3 is autosomal recessive.
To develop GPRA-crd3, a Glen must have 2 copies of the ADAM9 gene mutation i.e. it will have inherited 1 copy of the gene mutation from each parent.
A Glen with no copies of the gene mutation i.e. 2 normal genes will not develop GPRA-crd3.
A Glen with 1 copy of the gene mutation (and 1 normal gene) is a carrier but will not develop GPRA-crd3.
A Glen with 2 copies of the gene mutation is very likely to develop GPRA-crd3, although age of onset and progression of disease is highly variable. Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 Each puppy has a 1:4 (25%) chance of being
Normal / Clear ( + + ) status Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 Each puppy has a 1:2 (50%) chance of being
Carrier ( + - ) status Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 Each puppy has a 1:2 (50%) chance of being
Carrier ( + - ) status Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 Each puppy has a 1:4 (25%) chance of being
Affected ( - - ) status Inheritance of GPRA-crd3 : Inheritance of GPRA-crd3 DNA mutation test – what does this mean? : DNA mutation test – what does this mean? If breeders have their Glens DNA tested and employ “safe” breeding strategies, this means that:
We need never again produce Glen puppies that have 2 copies of the gene mutation, which means that no more Glens will ever again develop GPRA-crd3
We can eventually eliminate the disease gene from the gene pool DNA mutation test for GPRA-crd3 : DNA mutation test for GPRA-crd3 Offered by:
Animal Health Trust (AHT), UK – from 2011
Ruhr University, Bochum, Germany
The DNA test determines whether a Glen of Imaal Terrier has two, one or no copies of the gene mutation (ADAM9 deletion) that causes cone-rod dystrophy (GPRA-crd3). Animal Health Trust (AHT) : Animal Health Trust (AHT) www.aht.org.uk/genetics_tests.html
See under “Canine”:
Availability: Early 2011
Submission form: Available early 2011
Sample Required: TBC
Discounts available for 20+ samples submitted in one consignment Please email for details
Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU
Tel: 01638 555621 ~ Fax: 01638 555666 ~ Email: email@example.com OptiGen : OptiGen www.optigen.com/opt9_crd3_test.html
Test: Cone rod dystrophy (crd3)
Availability: Since June 2010
Submission form: www.optigen.com/opt9_request.html
Sample Required: Only blood samples accepted
Minimum of 3mls EDTA
Discount available for online submission (5%)
Discounts available for group testing (20+ dogs)
Group testing sessions: www.optigen.com
See under CLINIC SCHEDULE where UK sessions are also listed
OptiGen, Cornell Business & Technology Park, 767 Warren Road, Suite 300, Ithaca, New York 14850, USATel: (001) 607 257 0301 ~ Fax: (001) 607 257 0353 ~ Email: firstname.lastname@example.org Bochum : Bochum www.ruhr-uni-bochum.de/mhg/MITARBEITER/ARBEITSGRUPPEN/PRA/Glen%20Form%20english.pdf
Availability: Since June 2010
Submission form: See link above
Sample Required: Blood sample preferred
2 x 2 – 5mls EDTA
Please enquire about discounts for group testing
Humangenetik, Gebaeude MA 5, Ruhr-Universitaet, Universitaetsstr. 150, 44801 Bochum, Germany
Tel: 00 49 234 32-23839 ~ Fax: 00 49 234 32 14-196 ~ Email: email@example.com Safe breeding strategies : Safe breeding strategies “Safe” matings i.e. those that do not produce puppies that will go on to develop GPRA-crd3, must have at least one parent that has no copies of the gene mutation i.e. 2 normal genes; or at least one parent that is known to be hereditarily clear i.e. both its parents are known to have 2 normal genes.
“Safe” matings (with DNA-tested dogs/bitches) are:
Normal/Clear (+ +) x Normal/Clear (+ +)
= All the progeny will be hereditarily Normal/Clear (+ +)
Normal/Clear (+ +) x Carrier (+ -)
= Progeny have a 1:2 (50%) chance of being Normal/Clear (+ +) or a 1:2 (50%) chance of being Carrier (+ -) status
Normal/Clear (+ +) x Affected (- -)
= All the progeny will be Carrier (+ -) status
Both Dr Acland and Professor Epplen, in their presentations on 18th and 25th September respectively, advised that, to preserve the genetic diversity of the breed, breeders will need to include carriers of the ADAM9 mutation – both Carrier ( + - ) status and Affected ( + + ) – in breeding programmes in the early years following identification of the gene mutation.
Short term objectives: To avoid breeding puppies with 2 copies of the gene mutation
Long tem objectives: To eradicate the ADAM9 gene mutation from our breed Breeding strategies - safe matings : Breeding strategies - safe matings Breeding strategies – unsafe matings : Breeding strategies – unsafe matings Kennel Club Official DNA Testing Scheme : Kennel Club Official DNA Testing Scheme An official DNA testing scheme was approved by the Kennel Club (KC) in October 2010 and so results of DNA testing for GPRA-crd3 will now be sent to the UK Kennel Club, as well as to the owner.
Results will be entered onto the KC’s registration database
Results will be published in the KC’s quarterly Breed Records Supplement (BRS)
Results will be searchable via the KC website’s the “Health Test Result Finder”
www.thekennelclub.org.uk – see under “Dog Breeding”
Results will also appear on regularly updated lists on the KC website
www.thekennelclub.org.uk/item/315 – “DNA Screening Schemes and Results”
Results will appear on any new registration certificates issued and on the registration certificates of any future progeny (offspring)
Anyone who had their Glen DNA tested prior to approval of the official DNA testing scheme can now:
(i) submit the results for inclusion on the KC’s registration database
(ii) have the result put onto the registration certificate
Please send (i) a COPY of the DNA test certificate and (ii) the ORIGINAL registration certificate to:
Gary Johnson, Health & Breeder Services Department, The Kennel Club, 1 – 5 Clarges Street, Piccadilly, London, W1J 8AB Slide 20: Thank you! On behalf of Glens everywhere …