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% 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
|CARRIER x AFFECTED||AB and BB||A/B x B/B||50% AB
|AFFECTED x AFFECTED||BB and BB||B/B x B/B||100% BB||100% AFFECTED||100% AFFECTED|