PKD - the mutation Recently, the mutation which is suggested to cause PKD in cats was found by Dr. Leslie Lyons (University of Davis, USA). This mutation was found in all PKD affected cats but not in cats which were tested free by means of ultrasonic techniques.

PKD - the DNA test By DNA testing the mutation can be shown directly. The testing is carried out by state of the art laboratory methods and therefore provides a very high accuracy. In general DNA tests can be done at any age.

The test can be applied to Persian and Persian related cats, which were cross bred to Persians. With this test we can diagnose the reported mutation, but by no means we can report on the presence/absence of the disease (especially in breeds where the correlation of PKD disease and the cited mutation is not proven). The results that are transmitted contain the information on presence/absence of the C to A mutation in the PKD 1 gene exon 29 in the sample of the cat examined. We want to point out that there is still a small possibility of other mutations causing PKD which are not identified so far.

The onset of photoreceptor loss is around 5 weeks of age progressing to severe loss by the age of 16 weeks. Clinical symptoms include uncoordinated eye movement, increased eye-shine was reported as thinning of the retina progresses. Corneal thinning is not observed. Cats with one normal and one mutated gene (carriers) have normal vision although photoreceptor loss has been noted.

Other clinical signs include greasy skin and crusting of the skin around the face from where the mother has tried to groom them. Often more than one animal is affected per litter. Other abnormalities described in affected Birman cats include absence of whiskers and claws and abnormalities on the surface of the tongue.

The severe mutation: s

The mild mutation: m

Possible genotypes:

N/N Normal, cat does not have either the server or the mild mutations

N/s Carrier, cat has one copy of severe mutation but is healthy

N/m Carrier, cat has one copy of MPSVIm mutation but is healthy

s/s Affected, cat has 2 copies of the severe S mutation

m/m Affected, cat has 2 copies of the mutation

m/s Cat has one copy each of the severe and one copy of the mild mutation but may be otherwise healthy

• is validated for all cat breeds except Domestic Shorthair, and
  
• can now check for more 'b' allele variants than ever before including the b3 which was identified by researchers at Laboklin, and
  
• can check for the 'c' allele which is resposnible for the AB serotyp, and
  
• only available at Laboklin

A recent study at Laboklin identified a number of new variants involved in determining the different blood groups in cats. Our Genetic Blood Group DNA test has now been updated with the new variants and as a result we can now screen all cat breeds except Domestic Shorthair for genetic blood groups. The updated test can detect the 'b' mutation which is reposnible for blood group 'B' more accurately than before and in more breeds, and the 'c' mutation which is repsonsible for blood group 'AB' in Ragdoll and Bengal can now be detected.

The test is valid for all cat breeds except: Domestic Shorthair.

The new improved test is more comperhensive than any other commercially available tests.

Neonatal isoerythrolysis (NI):

This incompatibility reaction, especially important for breeders, is neonatal isoerythrolysis (NI). Neonatal isoerythrolysis in cats, also called fading kitten syndrome, is a dissolution of the red blood cells.

Only new born cats with blood groups A or AB (also known as C) whose mother has blood group B are affected by NI. In pedigree catteries, neonatal isoerythrolysis may occur in first-born and multiparous queens with blood group B, if they are mated to toms having blood groups A or AB (also known as C).

The kittens, with blood group A and AB (also known as C), which were born healthy, however, take up the mother's antibodies with the colostrum. These bind to the erythrocytes, which are then destroyed. Anaemia, excretion of protein in the urine and jaundice are the consequences, so that the kittens usually die within the first week of life. In some cases, the intestinal barrier is already closed at the time of birth, so that the absorption of the immunoglobulins by the kitten is prevented. Therefore, some theoretically at-risk kittens may not develop neonatal isoerythrolysis. Thus, not all kittens with blood groups A and C whose mother is type B develop NI.

Good to know Blood type B kittens whose mothers have blood group A do not develop NI. This is due to the low anti-B antibody titre in blood group A queens.

As a rule, new born kittens with clinical symptoms cannot be treated successfully. However, neonatal isoerythrolysis can be prevented by determining the blood groups of possible breeding partners in advance and avoiding mating between queens with blood group B and toms with types groups A or AB (also known as C). However, if such mating does occur, the kittens with blood groups A or AB (also known as C) should be separated from their type B mother in the first 16-24 hours after birth to prevent antibody uptake before the intestinal barrier is closed. For the genetic blood group determination, Laboklin requires either an EDTA blood sample (0.5 - 1 ml) or 2 cheek swabs. The sample run time after sample arrival is approx. 3-5 working days.

The differences between blood types is determined by the activity of cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH). CMAH is only active in type A erythrocytes and either absent or non-functional in type B red blood cells. This inactivity is caused by different mutations in the CMAH gene.

The original mutation which is causative for blood type B was found by Leslie A. Lyons research team and allows for correctly identifying 86 % of all type B cats which still left 14 % of serological type B cats misidentified, especially Ragdolls and Turkish Angora cats.

Our own research shows that additional screening for two other novel mutations correctly identifies 99% of all type B cats. By determining just these two novel variants all type A and B Ragdolls were identified correctly. These two mutations were also found to be causative for blood type B in Turkish Angora, Neva Masquerade, Scottish Fold as well as Domestic Shorthair cats

Leslie A. Lyons research team found another variant in CMAH which is responsible for blood type C (AB) in Ragdolls. We found that this specific mutation is not exclusively found in Ragdolls even though it is rare in other breeds. Type C Bengal cats could also be correctly identified by this mutation and it was also found in British Shorthairs, Maine Coons and Scottish Fold cats.

Since 2017 we practice a genotyping scheme with four variants, three of those to identify blood type B cats correctly and one additional to include the most common variant for blood type C.

The test now detects three genetic variants for the 'b' allele (268T>A, 179G>T, 1322delT) and one variant for the 'c' allele (364C>T).

The 3 'b' variants are also known as b1, b2, and b3.