LABOKLIN (UK)|Genetic Diseases | Dogs| Haemophilia B (factor IX deficiency)

Haemophilia B (factor IX deficiency)

Breed

Rhodesian Ridgeback .

The Disease

In cooperation with Prof. Dr. Mischke (Tierärztliche Hochschule Hannover) LABOKLIN was able to identify a missense-mutation in exon 7 of the factor IX gene that is responsible for the lack of active factor IX protein in Rhodesian Ridgeback Dogs.

Haemophilia B is a sex-linked disorder (x-chromosomal recessive). Male dogs express the disease when they have one mutated x-chromosome. The mutated x-chromosome comes from the bitch. In most cases female dogs are carrier of one mutated x-chromosome without being diseased (conductor). According to Mendel's Law of Inheritance, 50% of the male puppies of a carrier bitch will have the mutated x-chromosome and express the disease and 50% of the female puppies will be healthy carriers (conductors). Female dogs will be diseased when they have two mutated x-chromosomes (one from the mother, one from the father). In that case both, father and mother must have the mutated x-chromosome (e.g. diseased male dog bred to conductor bitch).

Trait of Inheritance

1. Homozygous healthy:

Genotype female: N(X)/N(X),
Genotype male: N(X)/Y (homozygous healthy)
A dog like this is healthy and does not carry the mutated x-chromosome. Offspring of this dog will not get the mutated x-chromosome.

2. Heterozygous carrier (only female):

Genotype female: N(X)/FIX(X) (heterozygous carrier)
A bitch like this carries one copy of the mutated gene. It is unlikely that the bitch will suffer from haemophilia B, however there is a 50% chance that she will pass on the mutation to her offspring.

3. Homozygous affected:

Genotype female FIX(X)/FIX(X) (homozygous affected)
Genotype male FIX(X)/Y (hemizygous affected)
Because of the x-chromosomal mode of inheritance, a homozygous affected female dog carries two mutated x-chromosomes and a homozygous affected male dog carries one mutated x-chromosome. Female and male homozygous affected dogs have a high risk to express haemophilia B. The bitch will pass on the mutation to a 100% of her offspring and 50% of the offspring of the male dog will get the mutated x-chromosome.

Inheritance : X-LINKED RECESSIVE trait

Sire
Dam Offspring

50 % Males 50 % Females

Clear
x
Clear
>
100% Clear

100% Clear

clear
x
carrier
>
50% Clear + 50% affected

50% Clear + 50% carriers

clear
x
affected
>
100% affected

100% carriers

affected
x
Clear
>
100% clear

100% carriers

affected
x
carrier
>
50% affected + 50% clear

50% affected + 50% carriers

affected
x
affected
>
100% affected

100% affected

Male:

Clear

Genotype: N [ normal ]

The dog is noncarrier of the mutant gene.
The dog will never develop Haemophilia B (factor IX deficiency) and therefore it can be used in breeding and should only be bred to clear females.

Affected

Genotype: FIX [ mutant ]

The dog carries the mutant gene and will pass it its entire female offspring.
The dog will develop Haemophilia B (factor IX deficiency) and will pass the mutant gene to its entire female offspring

Female:

Clear

Genotype: N / N [ Homozygous normal ]

The dog is noncarrier of the mutant gene.
The dog will never develop Haemophilia B (factor IX deficiency) and therefore it can be used in breeding and should only be bred to clear females.

Carrier

Genotype: N / FIX [ Heterozygous ]

The dog carries one copy of the mutant gene and one copy of the normal gene.
The dog will never develop Haemophilia B (factor IX deficiency) but since it carries the mutant gene, it can pass it on to its offspring.

Affected

Genotype: FIX / FIX [ Homozygous mutant ]

The dog carries two copies of the mutant gene and therefore it will pass the mutant gene to its entire offspring.
The dog will develop Haemophilia B (factor IX deficiency) and will pass the mutant gene to its entire female offspring

Description

DNA test

The mutation responsible for haemophilia B can now be identified using our DNA-test. The test can be performed on dogs of any age and even puppies can be tested. The DNA test does not only differentiate healthy and diseased dogs, but furthermore identifies healthy carrier (female) dogs. This is of crucial importance for dog breeders. To achieve a maximum reliability of the test result, we perform the DNA-test of each submitted sample in two independent test runs.

Sample Requirements

Whole blood in EDTA tube (0.5 - 1 ml) or Buccal Swabs.

Turnaround

within 7 working days

We will run this test 2 independant times on your sample to ensure that the result is 100% accurate

Price

£ 80.00 (including VAT)

LABOKLIN GmbH & Co. KG

ISO / DIN 17025 Accredited Laboratory

125 Northenden Road, Manchester, M33 3HF