Animal Molecular Breeding 2024, Vol.14, No.5, 326-334 http://animalscipublisher.com/index.php/amb 329 Figure 1 Cat eye related diseases (Adapted from Bott and Chahory, 2022) Image caption: A: Primary inferotemporal entropion with trichiasis and mucopurulent discharge in a 1-year-old male Maine Coon cat (affected bilaterally); B: Corneal sequestration in an 8-year-old female Persian cat; C: Persistent pupillary membrane in a 2-month-old male domestic shorthair cat; Anterior segment dysgenesis in a 5-month-old male domestic shorthair cat: (a) front view; and (b) lateral view (Adapted from Bott and Chahory, 2022) 5.2 Analysis of breeding practices in Breed X Breed X, identified here as the Burmese breed, has been extensively studied for its genetic predisposition to T2D. The high incidence of T2D in ABB cats is likely due to a genetic founder effect, which has been confirmed through genome-wide association studies identifying specific single-nucleotide polymorphisms (SNPs) associated with the disease (Table 1). Furthermore, the extent of linkage disequilibrium (LD) in Burmese cats is notably long, indicating a high degree of genetic similarity within the breed, which can exacerbate the prevalence of hereditary diseases (Alhaddad et al., 2013). This genetic homogeneity is a direct consequence of selective breeding practices aimed at maintaining breed standards, which inadvertently increase the risk of hereditary diseases. Table 1 Testing candidate SNPs in a validation cohort. DNA samples from a further 37 diabetic ABB cats, 47 normoglycaemic Australian-bred Burmese cats, and 84 Burmese cats from the low-prevalence US population were genotyped at the SNPs implicated by the GWAS (Adopted from Balmer et al., 2020) SNP A1 F_A F_U pValue OR Chromosome Position SNP1 T 0.59 0.38 0.00089 2.4 chrA3: 10995614 SNP2 G 0.29 0.52 0.00043 0.4 chrA3: 134626291 SNP3 C 0.17 0.46 5.35×10-6 0.2 chrC1: 23237623 SNP4 C 0.63 0.41 0.0013 2.5 chrC2: 83660325 SNP5 T 0.32 0.49 0.012 0.5 chrC2: 84129862 SNP6 A 0.30 0.34 0.53 0.8 chrC2: 84135537 Table caption: Results were analysed using Plink. A1 indicates the minor allele (i.e., least frequently observed based on the whole sample); F_A and F_U indicate the frequency of the minor allele in the affected and unaffected cats, respectively. The p value is shown calculated using Fisher’s Exact test and Bonferroni correction. No odds ratio could be calculated for SNP2 because the associated allele was not found in the non-diabetic cats (Adopted from Balmer et al., 2020) 5.3 Disease prevalence and management strategies The prevalence of hereditary diseases in cats varies significantly across breeds. For example, the prevalence of entropion in Persians and Maine Coons is 2.2%, while corneal sequestration is more common in Persians and Exotic Shorthairs, with a prevalence of 2.4%. In the case of Burmese cats, the high incidence of T2D necessitates targeted management strategies. Genetic screening and selective breeding practices are crucial in managing these hereditary conditions. The use of genome sequencing data has proven effective in identifying disease-causing variants and managing genetic diversity within feline colonies (Farias et al., 2017). Additionally, comprehensive breeding records and DNA panels can help breeders make informed decisions to reduce the incidence of hereditary diseases.
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