Determination of blood types in cats is important for clinical practices because of transfusion reactions and neonatal isoerythrolysis [2, 3]. Both transfusion reactions and neonatal isoerythrolysis are related to type B cats having high titer anti-A antibody [4, 5]. In our study, the prevalence of type B cats was found higher (67.1%) when compared to type A cats. In Turkey, the prevalence results associated with type B vary according to cat breeds. For example, in a previous study, the prevalence of type B cats was found higher than type A cats among Turkish Van cats. Also, type B prevalence (46.4%) was found nearly equal to type A (53.6%) in Turkish Angora cats . In another study, the prevalence of type B cats was found as 35.9%, 32.6%, 30.5%, and 6.1% in İstanbul, İzmit, Kırıkkale and Giresun, respectively, among non-pedigree cats . These findings and our results indicate that there might be a possible risk for neonatal isoerythrolysis among pedigree cats (Turkish Van and Angora) and stray cats living in İzmir, İstanbul, İzmit and Kırıkkale provinces of Turkey.
CMAH gene that is associated with blood group system is being studying in cats for about 15 years. To date, several SNPs as well as an 18 bp insertion have been detected by sequencing CMAH gene. Among these variations, some of them have also been associated with specific blood types. For example, Bighignoli et al. (2007) reported the 16 SNPs as well as an 18 insertion in CMAH gene of cats and among these, -217G > A, -371C > T, c.142G > A (originally G139A), c.268T > A (originally T265A), c.1603G > A (originally G1600A) and 18 bp insertion were found to be specific to blood group. Accordingly, homozygous forms of these variations specific to type B cats or heterozygous forms could be found in b allele carrier cats such as heterozygous type A and AB cats. In our study, C-371T was detected in type A, B and AB cats as heterozygous (C/T). Moreover, homozygous form of the − 371C > T polymorphism was found among only in type B cats. The remaining three SNPs (c.142G > A, c.268T > A, c.1603G > A) and 18 bp insertion were not detected in stray cats. These results demonstrate that there may be different variations in the CMAH gene between popular cat breeds and stray cats, and some of them are more common among popular cat breeds as well as being specific to blood groups. This assertion is actually supported by a study showing the presence of c.364C > T polymorphism in only Ragdoll cat breeds with AB blood group .
In a different study, c.179G > T, c.187A > G, c.1218T > C and c.1662G > A polymorphisms were detected in CMAH gene of type B cats as homozygous or heterozygous. c.187A > G was also detected in type AB cats as heterozygous . In our study, c.179G > T and c.1218T > C were found in type A, B and AB cats as heterozygous as well as c.187A > G in only type A and AB as heterozygous. c.1662G > A was not found in stray cats. In the following study, additional c.374C > T, c.593A > C, c.868A > C, c.898A > G, c.933delA, c.1322delT and c.1342G > A polymorphisms were detected as homozygous or heterozygous when analysed different cat breeds including Turkish Angora cats . The Turkish Angora cats that are one of the oldest cat breeds have been originated from Ankara region of Turkey which is relatively close to İzmir, our study area. Therefore, we conducted an additional comparison between Angora cats and stray cats living in İzmir for polymorphisms in CMAH gene. Accordingly, homozygous or heterozygous forms of c.139C > T, c.179G > T, c.187A > G and c.327A > C polymorphisms were detected as coherent in both groups. Moreover, 18 bp insertion that has not been detected in our study was found only in one type B cat among eight Turkish Angora cats analysed. These findings indicated that 139C > T, c.179G > T, c.187A > G and c.327A > C polymorphisms were prevalent in Turkey whereas 18 bp insertion was rare. Our previous study showing the prevalence of 18 bp insertion as 0.25% (2/791) also supports this result. .
Polymorphisms detected in CMAH gene have also been used as a genetic marker in the determination of blood groups. For example, Tasker et al. (2014) used two SNPs (G139A and C136T) to determine blood groups and reported that serological results were 96% compatible with those of molecular methods . -495C > T that is detected for the first time in our study and − 371C > T were found as homozygous (T/T) in same two type B cats. Depending on this, it was thought that the homozygous form of these polymorphisms can be used as a marker in the detection of type B cats in stray cats of İzmir. Similarly, it was thought that heterozygous form (A/C) of the 327A > C polymorphism detected only in type AB cats can be used to detect the type AB cats.
In cats, types of sialic acids related to blood groups are known. Accordingly, type A cats have Neu5Gc while type B cats have Neu5Ac. Neu5Ac can also be found at low levels in type A cats. Type AB cats have both Neu5Gc and Neu5Ac at similar levels. In our study, types of sialic acid were found as coherent with literature in blood groups. However, among two AB cats analysed, Neu5Ac was found higher (nearly 4 folds) in one. As the two cats were compared in terms of polymorphisms, only single position (1392T > C) was different. Depending on this, it was thought that the homozygous form of the polymorphism (C/C) can change Neu5Ac level in type AB cats because SNPs found in promotor, intron or exon regions of any gene have potential to change the level of protein/enzyme expressions .
In a previous study analysing 1394 cats from 25 distinct worldwide populations, it was reported that twelve mitotypes from A to L represented 83% of the cats and prevalence of A, B, C and D mitotypes were found as 66% among these cats . In Turkey, mitotypes of stray cats were identified for the first time and mitotypes A and A6 were found as more prevalent according to identified other mitotypes including D, E and 1. Grahn et al. (2011) identified mitotypes A, A6, B, D, D5, E, F, J, OL1 and U among Turkish Angora and Van cats. Moreover, mitotype D was found as prevalent in Turkish Van (62.5%; 10/16) and Angora cats (27%; 4/15) . These results indicate that in Turkey, mitotype A is prevalent in stray cats whereas mitotype D is prevalent in pedigree cats.