General Interpretations of Results
These are general interpretations of potential results. For disease-specific explanations, please refer to actual results that were emailed to you.
Mutation-Based Tests
For all autosomal recessive disorders, 1 = normal allele; 2 = disease variant allele. In general, we no longer encourage people to remove carrier dogs immediately from the limited gene pool that makes up a dog breed. We recommend testing the prospective parents for as many disorders as possible and then matching heterozygous dogs (carriers) that are of outstanding quality to homozygous normal (clear) dogs to preserve valuable genetic material. The offspring should then also be tested for future breeding purposes.
Marker-Based Tests (Autosomal Recessive Inheritance)
Since the actual disease variant is not known, one has to keep in mind that genetic test results using a linked marker can, in a few cases, lead to an incorrect conclusion about the animal’s true genetic status at the disease locus due to false alleles (same allele but not linked to the disease) or possible recombination between the marker and the disease allele. In other words, the further away a marker is from the disease-causing variant, the more likely the genotype will not match the phenotype. When interpreting linked marker tests, it is worthwhile checking with the testing laboratory how many samples have been run and how many “incorrect” results have been found.
Disease-Associated Variant/Alleles or Complex inheritance pattern
Most genetic diseases do not follow a simple mode of inheritance and/or can be caused by DNA variants in multiple genes occurring in the affected individual. This is true for several of the diseases with DNA tests that may have incomplete but useful predictive or diagnostic value. For these diseases, the result interpretations are specific for each genetic test.
Autosomal Recessive Disorders
NORMAL RESULT
Genotype: 1-1 (Homozygous Normal)
Phenotype: Healthy (Normal, Clear)
Interpretation: 1-1 (Homozygous Normal) dogs have two copies of a normal allele and NO COPIES of the disease variant allele that is found in dogs affected with […] in the breed. 1-1 dogs are not expected to develop signs of […] and none of their offspring can inherit the disease variant allele.
CARRIER RESULT
Genotype: 1-2 (Heterozygous)
Phenotype: Healthy (Carrier)
Interpretation: 1-2 (Heterozygous/Carrier) dogs have one copy of a normal allele and ONE COPY of the disease variant allele that is found in dogs affected with […] in the breed. 1-2 dogs are not expected to develop signs of […]. Each of the offspring of a 1-2 dog has a chance of inheriting the disease variant allele (2). Parents, offspring, breeding partners, and relatives should also be tested.
AFFECTED RESULT
Genotype: 2-2 (Homozygous)
Phenotype: Unhealthy (Affected)
Interpretation: Homozygous Affecteds (2-2) are expected to develop signs consistent with […] and all of their offspring will inherit a disease variant allele. Parents, offspring and relatives should also be tested. You may choose to contact us for a consultation on the management of this disease.
Autosomal Dominant Disorders
For all autosomal dominant disorders, 1 = normal allele; 2 = disease variant allele. In some cases, the “disease” trait may be a desired trait such as Merle in many dog breeds. Testing is particularly important because not all dominant traits are fully penetrant, such as Merle. Very often a “double dose” (homozygous affected; 2-2) leads to (worse) disease. Using Merle as an example, a 2-2 double merle dog can be blind, deaf and even have neurological disease.
NORMAL RESULT
Genotype: 1-1 (Homozygous Normal)
Phenotype: Healthy (Normal, Clear)
Interpretation: 1-1 (Homozygous Normal) dogs have two copies of a normal allele and NO COPIES of the disease variant allele that is found in dogs affected with […] in the breed. 1-1 dogs are not expected to develop signs of […] and none of their offspring can inherit the disease variant allele.
AFFECTED RESULT
Genotype: 1-2 (Heterozygous)
Phenotype: Unhealthy (Affected)
Interpretation: 1-2 (Heterozygous/Affected) dogs have one copy of a normal allele and ONE COPY of the disease variant allele that is found in dogs affected with […] in the breed. 1-2 dogs are expected to develop signs of […]. Each of the offspring of a 1-2 dog has a chance of inheriting the disease variant allele (2). Parents, offspring, breeding partners, and relatives should also be tested.
AFFECTED RESULT
Genotype: 2-2 (Homozygous)
Phenotype: Unhealthy (Affected)
Interpretation: Homozygous Affecteds (2-2) are expected to develop signs consistent with […] and all of their offspring will inherit a disease variant allele. Parents, offspring and relatives should also be tested. You may choose to contact us for a consultation on the management of this disease.
