Inheritance and result of DNA tests

The results of the DNA tests for CombiBreed are presented in a Clinical and Breeding Report, which contains a genetic profile, followed by clinical and breeding advice. This report is sent direct to the vet.

The genetic profile comprises the list of requested abnormalities with the associated genes/mutations and the results of the requested DNA test(s). This may be CLEAR, CARRIER or AFFECTED of the mutated gene. 

The OMIA database (Online Mendelian Inheritance in Animals) by the Australian professor Dr Frank Nicolas describes all the available DNA tests.

Mutations that have been described and validated in a single breed can also appear in other breeds, but these are often no longer published in scientific articles. Laboratories performing these tests can establish whether these mutations can be prevented in other breeds. It is not easy to determine how reliable a particular test is for a particular breed.
This basis described above applies in general to hereditary diseases. Naturally, inheritance and illnesses are biological processes, and so exceptions can occur. The specific information in a test describes the observations that may possibly apply.

Explanation of test results and inheritance:

The following inheratance and test results are discribed on this page:
Inheritance and results autosomal, recessive mutation
Inheritance and resutls autosomal, dominant mutation
Gender related (X-linked) condition

INHERITANCE AND RESULTS OF AUTOSOMAL, RECESSIVE MUTATION:

Autosomal, recessive inheritance means that an animal may be clear (normal homozygote), affected (abnormal homozygote) or carrier (heterozygote). Carriers can pass on the mutation in the population without themselves developing the symptoms. This makes it especially important for carriers to be identified in order to prevent the disease from spreading.

Explanation for veterinarians:
• An animal is CLEAR/NORMAL and has two healthy alleles (normal homozygote). The animal will not acquire any symptoms.
• An animal is CARRIER and has one healthy allele and one defective allele (heterozygote). The animal will not acquire any symptoms.
• An animal is AFFECTED and therefore has two defective alleles (abnormal homozygote). The animal will acquire symptoms of the disease.

Explanation for breeders:
• An animal is CLEAR/NORMAL and has two healthy alleles (normal homozygote). The animal will not acquire any abnormalities when breeding and cannot pass on the abnormality to the next generation.
• An animal is a CARRIER and has one healthy allele and one defective allele (heterozygote). The animal will pass on the mutant (defective) gene to half of its offspring. In a number of cases carriers may also develop symptoms from the defective allele, but as a rule do not have any symptoms.
• An animal is AFFECTED and therefore has two defective alleles (abnormal homozygote). An affected will pass on the defective allele to all their offspring in the next generation, and will themselves develop the symptoms associated with the disease.  

Inheriticance autosomal recessive:  Parents:      Reproductive cells:  Offspring:  Interpretation breeding :  Interpretation veterinarian: 

NORMAL  x NORMAL

AA and AA

A/A x A/A

100% AA 

100% NORMAL

100% HEALTHY

NORMAL x CARRIER

AA and AB

A/A x A/B

50% AA

50% AB

    

50% CARRIER

100% HEALTHY

NORMAL x AFFECTED

AA and BB

A/A x B/B

100% AB

100% CARRIER

100% HEALTHY

CARRIER x CARRIER

AB and AB

A/B x A/B

25% AA

50% AB

25% BB

25% NORMAL

50% CARRIER

25% AFFECTED

75% HEALTHY

25% AFFECTED

CARRIER x AFFECTED

AB and BB

A/B x B/B

50% AB

50% BB

50% CARRIER

50% AFFECTED

50% HEALTHY

50% AFFECTED

AFFECTED x AFFECTED

BB and BB

B/B x B/B

100% BB

100% AFFECTED

100% AFFECTED


INHERITANCE AND RESULT OF AUTOSOMAL, DOMINANT MUTATION
:

Autosomal, dominant inheritance means that an animal may be clear (normal homozygote), a sufferer (abnormal homozygote) or carrier (heterozygote). Carriers and affected will both have the symptoms of the mutation.

Explanation for veterinarians:
• An animal is CLEAR/NORMAL and has two healthy alleles (normal homozygote). The animal will not acquire any symptoms.
• An animal is a CARRIER and has one healthy allele and one defective allele (heterozygote). The animal will acquire symptoms of the disease.
• An animal is AFFECTED and therefore has two defective alleles (abnormal homozygote). The animal will acquire symptoms of the disease.

Explanation for breeders:
• An animal is CLEAR/NORMAL, and in that case will have two healthy alleles (normal homozygote). This animal will not acquire any abnormalities when breeding and cannot pass on the abnormality to the next generation.
• An animal is a CARRIER, where it will have a healthy allele and a defective allele (heterozygote). The animal will pass on the mutant allele to half of its offspring. Carriers can themselves also become sick.
• An animal is a AFFECTED, which means it has two defective alleles (abnormal homozygote). Sufferers pass on the defective allele to all their offspring in the next generation, and will also develop symptoms associated with the disease. 

Inheritance autosomal dominant:  Parents:  Reproductive cells:  Offspring:  Interpretation breeding:  Interpretatie veterinatian: 

NORMAL x NORMAL

AA and AA

A/A x A/A

100% AA

100% NORMAL

100% HEALTHY

NORMAL x CARRIER

AA and AB

A/A x A/B

50% AA

50% AB 

50% NORMAL

50% CARRIER

50% HEALTY

50% AFFECTED

NORMAL x AFFECTED

AA and BB

A/A x B/B 

100% AB 

100% CARRIER

100% AFFECTED

CARRIER x CARRIER

AB and AB

A/B x A/B

25% AA

50% AB

25% BB 

25% NORMAL

50% CARRIER

25% AFFECTED

25% HEALTHY

75% AFFECTED 

           

CARRIER x AFFECTED

AB and BB

A/B x B/B 

50% AB

50% BB 

50% CARRIER

50% AFFECTED

100% AFFECTED

AFFECTED x AFFECTED

BB and BB

B/B x B/B

100% BB

100% AFFECTED

100% AFFECTED

 

GENDER-RELATED (X-LINKED) CONDITIONS: 

These are usually illnesses where the gene is located on the sex chromosomes (X-chromosome and Y-chromosome). A female animal has two X-chromosomes, whereas a male animal has only one X-chromosome and one Y-chromosome.

INHERITANCE FOR DAUGHTERS: SEE OTHER INHERITANCE, EITHER AUTOSOMAL, RECESSIVE OR AUTOSOMAL, DOMINANT.
BELOW IS THE TABLE FOR INHERITANCE OF MALE OFFSPRING

 Inheritance X-linked: Parents: Reproductive cells:  Offspring:  Interpretation breeding:  Interpretation veterinarian: 

NORMAL DAM x

NORMAL SIRE 

AA and AY

A/A X A/Y

SONS 100% AY 

SONS 100% NORMAL 

SONS 100% HEALTHY

NORMAL DAM x

CARRIER  SIRE

AA and BY

A/A x B/Y

SONS 100% AY

SONS 100% NORMAL

SONS 100% HEALTHY 

CARRIER DAM x NORMAL SIRE

AB and AY

A/B x A/Y

SONS  

50% AY

50% BY 

SONS  

50% CARRIER

50% AFFECTED

SONS

50% HEALTHY

50% AFFECTED

CARRIER DAM  x AFFECTED SIRE 

AB and BY

A/B x B/Y

SONS

50% AY

50% BY 

SONS

50% CARRIER

50% AFFECTED

SONS

50% HEALTHY

50% AFFECTED

AFFECTED DAM x VRIJE VADER

BB and AY

B/B x A/Y

SONS 100% BY

SONS 100% AFFECTED 

SONS 100% AFFECTED

AFFECTED DAM x AFFECTED SIRE

BB and BY

B/B x B/Y

SONS 100% BY 

SONS 100% AFFECTED 

SONS 100% AFFECTED 


Important note!
It cannot be excluded that additional mutations at other locations at the genome cause similar conditions.

Mutations that have been described and validated in a single breed can also appear in other breeds, but these are often no longer published in scientific articles. Laboratories performing these tests can establish whether these mutations can be prevented in other breeds. It is not easy to determine how reliable a particular test is for a particular breed.
This basis described above applies in general to hereditary diseases. Naturally, inheritance and illnesses are biological processes, and so exceptions can occur. The specific information in a test describes the observations that may possibly apply.