Dog Genetics – Introduction to Modes of Inheritance

In previous years, big advances have been made in understanding of dog genetics. Different traits or inherited diseases differ among each other in modes of inheritance. Progress in the field of dog genetics, the CanMap project and recognition of a dog as a model for a number of inherited diseases in humans led to identification of mutations associated with many different diseases and traits found in various dog breeds.

Now breeders can take care of their breeding stock by DNA testing for neurodegenerative, cardiovascular, sensory, renal, metabolic and other numerous disorders. A lot of information of dog disease genetics was acquired in a short amount of time. Although it will take time to fully come to understanding all of the findings, it is necessary for breeders to understand the DNA tests results they get for their dogs. To be able to put the results to use in practice, basic knowledge of modes of inheritance is needed.

In following schemes you can find explanations of autosomal recessive and autosomal dominant inheritance, and a bit more complicated X-linked recessive and X-linked dominant inheritance.

Dog Genetics – Modes of Inheritance

Autosomal recessive inheritance

Autosomal dominant inheritance

X-linked recessive inheritance

X-linked dominant inheritance

Additional explanation for X-linked inheritance

d

X-linked recessive inheritance is a mode of genetic inheritance, where the recessive gene is located at the X chromosome. Disorders inherited as X-linked recessive disorders affect males more often than females.

X and Y are the sex chromosomes. Females have two X chromosomes, inherited from mother and father. This means that for females, it is more probable to inherit the chromosome with the defected gene. When possessing defected gene, the female can be homozygote (two copies of defected gene) or heterozygote (one copy of defected gene).  A heterozygous female will not display symptoms of the disease, but is a carrier. Homozygous female will develop disease’s symptoms.

Males have one X and one Y chromosome, and the X chromosome is always inherited only from the mother. The male dog will be affected in case of inheriting the defected gene from affected mother. If the mother is homozygous for the defected gene, the chances are 100% that the male puppy will be affected. If the mother is heterozygous for the defected gene, the chances are 50% that the male puppy will be affected and 50% it will be healthy.

a

X-linked dominant inheritance is a mode of genetic inheritance, where the dominant gene is located at the X chromosome. This mode of genetic inheritance is less common than the X-linked recessive inheritance, and it does not necessarily affect males more often than females, unlike X-linked recessive inheritance.

X and Y are the sex chromosomes. Females have two X chromosomes, inherited from mother and father. This means that for females, it is more probable to inherit the chromosome with the defected gene. When possessing defected gene, the female can be homozygote or heterozygote, but will always be affected.

Males have one X and one Y chromosome, and the X chromosome is always inherited only from the mother. The male dog will be affected in case of inheriting the defected gene from affected mother. If the mother is homozygous for the defected gene, the chances are 100% that the male puppy will be affected. If the mother is heterozygous for the defected gene, the chances are 50% that the male puppy will be affected and 50% it will be healthy.

We hope that looking at these schemes got things about inheritance and dog genetics clearer for you. Nevertheless, AnimaLabs team is always at your service to help you with questions of your test results and possible mating or advices about DNA tests available for your dog breed.