*The complete panel tests for five genetic variants that allow the determination of all relevant genotypes and therefore phenotypes for all breeds (from Kelh et al., 2018 et Kelh et al., 2019 manuscripts).
Gene affected: CMAH
A > ac > b
Thus, the following genotypes can be observed:
Type A: A/A, A/b et A/ac 
Type  B: b/b 
Type C: ac/ac ou ac/b

Mutations : 
Felis_catus_9.0 B2 g.4938728T>A c.268T>A variant corresponding to Type B in most cats
Felis_catus_9.0 B2 g.4947519C>T c.364C>T variant corresponding to Type C in some Ragdolls
Felis_catus_9.0 B2 g.4935385G>T c.179G>T variant corresponding to Type B in most Turkish breeds
Felis_catus_9.0 B2 g.4978934delT c.1322delT variant corresponding to Type B in some Ragdolls
*The three CMAH variants c.179G>T, c.268T>A and c.1322delT are the main reasons for the defective synthesis of NeuGc causing blood type B in purebred and domestic cats.
OMIA link: 000119-9685

Breeds suitable for testing : All breeds, including Ragdolls, Turkish breed and some domestic shorthair cats

Description:
In domestic cats, the AB blood group system includes the three types A, B, and C (also known as AB), which vary in frequency across breeds and geographic regions. Kehl et al. 2018 reports that of 421 phenotypically typed cats, 60% were A, 35% B, and 5% C.
The c.268T>A variant of CMAH is observed in B-type cats for most breeds, and the c.179G>T variant results in a B-type in Turkish breeds. The c.1322delT variant is indicative of a B blood type in some Ragdolls and while the c.1322delT variant correlates with the b allele in domestic shorthair cats.
Siamese, Tonkinese and Burmese breeds are almost fixed for type A, while the prevalence for type B in British Shorthairs, Birmans, Devon and Cornish Rex can vary between 25 and 50 %. (Giger and Bucheler, 1991). Although type B cats are rare in randomly bred populations, mixing with other breeds of cats increases the frequency of type B cats in this population. The occurrence of blood type C is less than 1%.
Strategy for genotyping:
Detection of the c.268T>A, c.179G>T, c.1322delT variants leads to an excellent method of identifying A and B blood groups in 99% of cats. The c.364C>T variant identifies a large number of cats with blood group C (AB, Ragdolls).

Breeding strategy:
Avoid mating b allele carriers with other 'b' carriers to avoid obtaining serologically B kittens.
Blood group B cats should only be bred to group B cats.

See the Labgenvet website for more information about blood type.
Blood Group AB, blood types and the A, aAB, and b alleles in cats
Cat genetic profile - Feline blood groups

References:
Kehl, A., Heimberger, K., Langbein-Detsch, I., Boehmer, S., Raj, K., Mueller, E., Giger, U. (2018) Molecular characterization of blood type A, B, and C (AB) in domestic cats and a CMAH genotyping scheme. PLoS One 13:e0204287, 2018. Pubmed reference: 30235335. DOI: 10.1371/journal.pone.0204287.
Gandolfi, B., Grahn, R.A., Gustafson, N.A., Proverbio, D., Spada, E., Adhikari, B., Cheng, J., Andrews, G., Lyons, L.A., Helps, C.R. (2016) A novel variant in CMAH is associated with blood type AB in Ragdoll cats. PLoS One 11:e0154973, 2016. Pubmed reference: 27171395. DOI: 10.1371/journal.pone.0154973.
Giger, U., Bucheler, J., Patterson, D.F. (1991) Frequency and Inheritance of A and B Blood Types in Feline Breeds of the United-States Journal of Heredity 82:15-20, 1991. Pubmed reference: 1997588