Haemophilia A (factor 8 deficiency)

Haemophilia A is one of the most important inherited disorders of haemostasis in Havanese Dogs. The underlying pathomechanism of Haemophilia A is a lack or decreased activity of factor VIII that plays a critical role in the coagulation cascade. Affected dogs present with hemorrhage that can vary from mild to severe depending on the degree of the disease. The clinical signs include haematomas of large sizes, bleeding of the nose, skin, muscles and joints. If the disease is severe and no precautions are taken, affected dogs can bleed to death after surgery or injury. In cooperation with Prof. Dr. Mischke (Tierärztliche Hochschule Hannover) LABOKLIN was able to identify a SINE insert in exon 14 of the factor VIII gene that is responsible for the lack of active factor VIII protein in Havanese Dogs.
Haemophilia A 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

There are 3 possible genotypes:
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)/FVIII(X) (heterozygous carrier)
A bitch like this carries one copy of the mutated gene. It is unlikely that the bitch will suffer from haemophilia A, however there is a 50% chance that she will pass on the mutation to her offspring.

3. Homozygous affected:
Genotype female FVIII(X)/FVIII(X) (homozygous affected)
Genotype male FVIII(X)/Y (hemizygous affected)
Because of the x-chromosomal mode of inheritance, a homozygous affected female dog carries two mutated x-chromosomes and a hemizygous affected male dog carries one mutated x-chromosome. Female and male affected dogs have a high risk to express haemophilia A. 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.

Sample requirement: Whole blood in EDTA tube (0.5 – 1 ml) or Buccal Swabs. (EDTA Blood Tube or Buccal Swab will be provided free of charge)

Turnaround: 2-3 weeks. 

The test will be ran two independent times on your sample to ensure that the result is 100% accurate.

Price includes VAT.