Testing of cats: Blood Group DNA test

Determination of blood groups in cats - DNA test

Note: this genetic test is not suitable for Ragdoll and Turkish Angora cats.

In cats three serological blood group types are known - group A, B and rare group AB.

Group A is the most common - breeds that have A group only: Siamese cats, Burmese cats, Russian Blue cats, Ocicat and Oriental Shorthair cats (source Leslie A Lyons).

Breeds with more frequent occurrence of B blood group: British Shorthair cats, Cornish Rex and Devon Rex.

The occurrence of blood group AB is below 1%.

Geographical differences in the incidence of blood groups in cat breeds have been described as well.

Cat antigens are known. A blood group is associated with N-glykolylneuramin acid (NeuGc), B blood group is associated with N-acetylneuramin acid (NeuAc). Gene CMAH codes cytidinmonofosfat-N-acetylneuramin hydroxylase enzyme, which catalyses the conversion of NeuAc to NeuGc. Gene mutation in CMAH gene causes the existence of A and B blood group (Bighignoli et al. 2007).

The frequency of blood groups in breeds, including comparison of geographic differences in occurrence blood groups

* Source: University of Pennsylvania

** Source: Studies Germany

*** In this race was also proved a rare AB group occurrence

Methods of determination blood groups in cats

A very common way of cat blood groups determination is based on presence of antibodies in blood. This is typically used by commercially available indicator strips. The test is relatively cheap and quick. It is able to differentiate the blood group A, B and AB. For this blood samples can be used only.

Another possible way of cat blood groups determination is detection of mutations in CMAH gene (this gene is responsible for the "b" allele - "b" allele refers below). For this examination buccal swab samples or blood samples can be used.

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The principle of genetic determination of presence or absence b allele

Mutations, associated with B blood group, have been found in CMAH gene (gene is coding cytidinmonofosfat-N-acetylneuramin hydroxylase enzyme). Following genetic variants leading to disruption of normal gene function have been found: G-108A, G-217A, C-371T, A-468G, G-539A and 18 bp insertion at position -53 in 5' non-translate area of CMAH gene. These mutations cause NeuAc predominance and manifest in homozygous status in individuals with B blood group (Bighignoli 2007).

Genetic system of cat blood groups can be expressed: A> a^ab> b. A allele is dominant over b allele. That means, if a cat has A/b genotype, serological blood group type is A. It is important to realize that the AB blood group is coded differently from A and B group (Bighignoli et al. 2007).

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Variants of genotypes - phenotypes (serological blood groups) association:

A / A - serological blood group A

A / a^ab - serological blood group A

A / b - serological blood group A

a^ab / b - serological blood group AB

a^ab / a^ab - serological blood group AB

b / b - serological blood group B

Genetic test can determinate allele b carrier individuals because of detecting presence or absence of mutations in the gene CMAH.

Genetic test identifies recessive b allele, which is in homozygous status associated with serotypes B:

• Cat, carrying two copies of allele b, always has B blood group.
• Cat with one copy of b allele may have a blood type A (genotype A/b) or rare blood type AB (genotype  a^ab/b)

Genetic test is not able to distinguish between A blood group type and rare AB blood group.

The absence of b allele (non-b allele) may mean serological blood group A (genotype A/A) or rare AB (genotype a^ab/a^ab).

Result codes of molecular genetic test for determining the presence / absence of allele b:

• non-b/non-b - an individual without any b allele, serological blood group A or AB
• non-b/b - one b allele carrier individual, serological blood group A or AB
• b/b - an individual with two copies of b allele, serological group B

The genetic test is not suitable for Ragdoll and Turkish angora.

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Why it is good to know the blood group of your cats?

The knowledge of blood groups in cats is important in any need of blood transfusions and in case of neonatal isoerytrolysis (NI) in newborn kittens.

If a transfusion is needed, donor's and recipient's blood group should be determined. Incompatible blood transfusion leads to acute hemolytic anemia. In general, transfusion reactions may be caused by non-immune infections such as infection by contaminated blood, bad blood storage or application, etc. Immune incompatibility reaction is occurred if blood group B individual receives A blood type. Within several minutes or hours destruction of red blood cells type A occurs. At the end the affected individual suffers from severe anaphylactic reactions and intravascular haemolysis.

For cat breeders, it is important to know blood group and related aloantibodies of their cat, to prevent incompatible response in kittens - neonatal isoerytrolysis (NI). Kittens are born without aloantibodies. Aloantibodies are created during cat's life, they start creating in 6-8 weeks and they reach full titre in 3 months.

Kittens can be suffered from NI in case they were born from crossbreeding B blood type female-cat + A blood type male-cat. Risk arises for kittens with A blood group (in fact these kittens are genetically A/b). Kittens are fed with colostrum, from witch kittens obtain anti-A antibodies. These anti-A antibodies destroy their own erythrocytes. Within a few hours hemolytical disease develops and kittens are in danger to life. Attendant symptoms of hemolytical disease are disappearance of the suction reflex, lethargy, restlessness, icterus, brown colour of urine.

The main prevention of NI is to find out blood groups of cat-parents before mating.

References:

Bighignoli B., Niini T., Grahn R. A., Pedersen  N. C., Millon L. V., Polli M., Longeri M., Lyons  L. A.: Cytidine monophospho-N-acetylneuraminic acid hydroxylace (CMAH) mutations associated with domectic cat AB blood group.