Optigen - prcd PRA
The OptiGen prcd-PRA test is a DNA-based test that helps you avoid one form of Progressive Retinal Atrophy (PRA). PRA refers to a group of diseases that cause the retina of the eye to degenerate slowly over time. The result is declining vision and eventual blindness. “prcd” stands for “progressive rod-cone degeneration” which is the type of PRA known in several breeds.
The genetic disorder, prcd-PRA , causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to develop normally early in life. The “rod” cells operate in low light levels and are the first to lose normal function. Night blindness results. Then the “cone” cells gradually lose their normal function in full light situations. Most affected dogs will eventually be blind. Typically, the clinical disease is recognized first in early adolescence or early adulthood. Since age at onset of disease varies among breeds, you should read specific information for your dog. Diagnosis of retinal disease can be difficult. Conditions that seem to be prcd-PRA might instead be another disease and might not be inherited. OptiGen’s genetic test assists in making the diagnosis. It’s important to remember that not all retinal disease is PRA and not all PRA is the prcd form of PRA. Annual eye exams by a veterinary ophthalmologist will build a history of eye health that will help to diagnose disease.Unfortunately, at this time there is no treatment or cure for PRA. If your dog is affected, you may find it helpful to read about other owners’ experiences living with blind dogs. (suggested links:www.eyevet.org and www.blinddogs.com)
Inheritance Prcd-PRA is inherited as a recessive trait. This means a disease gene must be inherited from each parent in order to cause disease in an offspring. Parents were either “carrier” or affected. A carrier has one disease gene and one normal gene, and is termed “heterozygous” for the disease. A normal dog has no disease gene and is termed “homozygous normal” – both copies of the gene are the same. And a dog with two disease genes is termed “homozygous affected” – both copies of the gene are abnormal.
Inheritance -
It’s been proven that all breeds being tested for prcd-PRA have the same disease caused by the same mutated gene. This is so, even though the disease might develop at different ages or with differing severity from one breed to another.
Although prcd-PRA is inherited, it can be avoided in future generations by testing dogs before breeding. Identification of dogs that do not carry disease genes is the key. These "clear" dogs can be bred to any mate - even to a prcd-affected dog which may be a desirable breeding prospect for other reasons. The chance of producing affected pups from such breedings depends on the certainty of test results. Again, you’ll find the specific information on certainty of test results for your dog by linking to breed specific information.
The Genetic Test The OptiGen prcd test is done on a small sample of blood from the dog. The test analyzes the specific DNA mutation causing prcd-PRA. The OptiGen test detects the mutant, abnormal gene copy and the normal gene copy. The result of the test is a genotype and allows separation of dogs into three groups: Normal/Clear (homozygous normal), Carrier (heterozygous) and Affected (homozygous mutant).
Possible results using the OptiGen prcd test Genotype Risk Group Significance For Breeding Risk of prcd Disease
Homozygous Normal Normal/Clear Can be bred to any dog, extremely low risk of producing affecteds Extremely low
Heterozygous Carrier Should be bred only to Normal/Clear to remove risk of producing affecteds Extremely low
Homozygous Mutant Affected Should be bred only to Normal/Clear to remove risk of producing affecteds Very high
The genetic disorder, prcd-PRA , causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to develop normally early in life. The “rod” cells operate in low light levels and are the first to lose normal function. Night blindness results. Then the “cone” cells gradually lose their normal function in full light situations. Most affected dogs will eventually be blind. Typically, the clinical disease is recognized first in early adolescence or early adulthood. Since age at onset of disease varies among breeds, you should read specific information for your dog. Diagnosis of retinal disease can be difficult. Conditions that seem to be prcd-PRA might instead be another disease and might not be inherited. OptiGen’s genetic test assists in making the diagnosis. It’s important to remember that not all retinal disease is PRA and not all PRA is the prcd form of PRA. Annual eye exams by a veterinary ophthalmologist will build a history of eye health that will help to diagnose disease.Unfortunately, at this time there is no treatment or cure for PRA. If your dog is affected, you may find it helpful to read about other owners’ experiences living with blind dogs. (suggested links:www.eyevet.org and www.blinddogs.com)
Inheritance Prcd-PRA is inherited as a recessive trait. This means a disease gene must be inherited from each parent in order to cause disease in an offspring. Parents were either “carrier” or affected. A carrier has one disease gene and one normal gene, and is termed “heterozygous” for the disease. A normal dog has no disease gene and is termed “homozygous normal” – both copies of the gene are the same. And a dog with two disease genes is termed “homozygous affected” – both copies of the gene are abnormal.
Inheritance -
It’s been proven that all breeds being tested for prcd-PRA have the same disease caused by the same mutated gene. This is so, even though the disease might develop at different ages or with differing severity from one breed to another.
Although prcd-PRA is inherited, it can be avoided in future generations by testing dogs before breeding. Identification of dogs that do not carry disease genes is the key. These "clear" dogs can be bred to any mate - even to a prcd-affected dog which may be a desirable breeding prospect for other reasons. The chance of producing affected pups from such breedings depends on the certainty of test results. Again, you’ll find the specific information on certainty of test results for your dog by linking to breed specific information.
The Genetic Test The OptiGen prcd test is done on a small sample of blood from the dog. The test analyzes the specific DNA mutation causing prcd-PRA. The OptiGen test detects the mutant, abnormal gene copy and the normal gene copy. The result of the test is a genotype and allows separation of dogs into three groups: Normal/Clear (homozygous normal), Carrier (heterozygous) and Affected (homozygous mutant).
Possible results using the OptiGen prcd test Genotype Risk Group Significance For Breeding Risk of prcd Disease
Homozygous Normal Normal/Clear Can be bred to any dog, extremely low risk of producing affecteds Extremely low
Heterozygous Carrier Should be bred only to Normal/Clear to remove risk of producing affecteds Extremely low
Homozygous Mutant Affected Should be bred only to Normal/Clear to remove risk of producing affecteds Very high
Optigen FN
The OptiGen FN test is a DNA-based test that accurately diagnoses a fatal kidney disease that occurs in English Cocker Spaniels (ECS). The test also detects CARRIERS of this disease and clears dogs that are genetically NORMAL. Familial Nephropathy (FN) has been referred to in several ways: kidney failure, fatal renal disease, juvenile nephropathy, renal cortical hypoplasia, hereditary nephritis (HN), Autosomal Hereditary Recessive Nephropathy (AHRN) in canines and Alport's Syndrome in humans. Among ECS breeders in the U.S. , the most common reference is to “FN” and this term is used to name the OptiGen test.
FN is inherited in an autosomal recessive pattern in the ECS. This means the gene mutation responsible for FN is located on an autosome (that is, a chromosome that is not a sex chromosome) and FN disease results when the gene mutation is passed to the offspring by both the mother and the father. (A similar kidney disease in other breeds can be caused by different gene mutations with X-linked or dominant inheritance.)
FN disease is a juvenile-onset fatal kidney (renal) failure recognized in ECS worldwide for more than 50 years. The renal disease caused by FN invariably is progressive and ultimately fatal; however, the rate of disease progression observed in affected dogs is more rapid in some individuals than in others.
Dogs with FN typically develop chronic renal failure between 6 months and 2 years of age, with eventual and sometimes rapid destruction of both kidneys. The early clinical signs are the same as those associated with chronic renal failure due to any other cause. These include excessive water consumption, excessive urine volume, reduced growth rate or weight loss, poor quality hair coat, reduced appetite, and vomiting. Persistent high levels of protein in the urine of a young ECS most often proves to be due to FN.
FN is inherited in an autosomal recessive pattern in the ECS. This means the gene mutation responsible for FN is located on an autosome (that is, a chromosome that is not a sex chromosome) and FN disease results when the gene mutation is passed to the offspring by both the mother and the father. (A similar kidney disease in other breeds can be caused by different gene mutations with X-linked or dominant inheritance.)
FN disease is a juvenile-onset fatal kidney (renal) failure recognized in ECS worldwide for more than 50 years. The renal disease caused by FN invariably is progressive and ultimately fatal; however, the rate of disease progression observed in affected dogs is more rapid in some individuals than in others.
Dogs with FN typically develop chronic renal failure between 6 months and 2 years of age, with eventual and sometimes rapid destruction of both kidneys. The early clinical signs are the same as those associated with chronic renal failure due to any other cause. These include excessive water consumption, excessive urine volume, reduced growth rate or weight loss, poor quality hair coat, reduced appetite, and vomiting. Persistent high levels of protein in the urine of a young ECS most often proves to be due to FN.
Genetic Testing:
Early in the disease course, a diagnosis can be difficult. Definitive clinical diagnosis can require examination of kidney tissue after death. The FN genetic test solves this problem immediately since presence of the FN gene mutation is accomplished by testing a DNA sample. This result gives the owner immediate diagnostic information and aides in making decisions for the affected dog and for breeding strategies.
Because the OptiGen FN test is a mutation-based gene test, it accurately and specifically identifies normal dogs, carriers (heterozygous dogs) and affecteds. Possible test results are listed in the table below.
Possible results using the OptiGen FN test N =Normal(Clear)Homozygous for normal gene, so will never develop the diseaseC = Carrier Carries one disease gene, but will never develop the diseaseA =AffectedHomozygous for disease gene and will develop the disease
Early in the disease course, a diagnosis can be difficult. Definitive clinical diagnosis can require examination of kidney tissue after death. The FN genetic test solves this problem immediately since presence of the FN gene mutation is accomplished by testing a DNA sample. This result gives the owner immediate diagnostic information and aides in making decisions for the affected dog and for breeding strategies.
Because the OptiGen FN test is a mutation-based gene test, it accurately and specifically identifies normal dogs, carriers (heterozygous dogs) and affecteds. Possible test results are listed in the table below.
Possible results using the OptiGen FN test N =Normal(Clear)Homozygous for normal gene, so will never develop the diseaseC = Carrier Carries one disease gene, but will never develop the diseaseA =AffectedHomozygous for disease gene and will develop the disease
- The OptiGen FN test can be done reliably at any age – even in young pups, and the result will be the same at any age, and will be the same whenever it is repeated.
- The exact frequency of this disease, and of the gene mutation causing it, are not known as yet. Data accumulated through genetic testing will help to provide that information.
- Tallies of test results are updated and provided quarterly to national breed clubs.