👤 D Casamian-Sorrosal

A mutation identified in the myosin binding protein C3 gene (MYBPC3 R820W) has been associated with hypertrophic cardiomyopathy (HCM) in Ragdoll cats. Ragdolls with HCM are reported to have a poor prognosis and homozygous cats seem particularly likely to develop severe HCM, although the outcome in Ragdolls tested for the MYBPC3 mutation has not been reported. We aimed to determine the influence of genotype on survival in Ragdoll cats using a questionnaire, and hypothesized that homozygous Ragdolls had shorter lifespans and were more likely to suffer cardiac death than heterozygous or wild-type (WT) cats. 251 client owned Ragdoll cats. A questionnaire for breeders/owners of MYBPC3 genotyped Ragdolls included items related to genotype, age, sex, current status (alive/dead), and date and circumstances of death. Death was categorized as cardiac or non-cardiac. Survival was analyzed using Kaplan-Meier curves and log rank tests. Completed questionnaires were received for 236 cats (156 WT, 68 heterozygous, 12 homozygous). Median survival time for homozygous cats was 5.65 years (95%CI 0.4-10.9 years) compared to heterozygous (>16.7 years) or WT (>15.2 years). Homozygous cats were more likely to die from cardiac death (p = 0.004 vs. WT; p = 0.003 vs. heterozygous) and had significantly shorter time to cardiac death (vs. WT p < 0.001; vs. heterozygous p < 0.001). Ragdoll cats homozygous for the MYBPC3 R820W mutation have a shorter survival time than WT or heterozygous cats. This suggests a mode of inheritance that follows an incomplete dominance pattern. Show less

To determine prevalence and demographics of two myosin-binding protein C (MYBPC3) mutations that affect ragdolls (R820W) and Maine coons (A31P) in the British Isles. From the database of a genetic testing laboratory samples from 2018 ragdolls and 742 Maine coons were analysed with respect to mutation status, age, sex and county of origin. The actual prevalence was compared to the expected Hardy-Weinberg prevalence by chi-squared test. The prevalence of the R820W mutation in ragdolls was 27% (25·6% heterozygous, 1·4% homozygous), and that of the A31P mutation in Maine coons was 39·4% (36·4% homozygous, 3% heterozygous). There were more female cats (69·5% ragdoll, 70·3% Maine coon). The median age was 6·4 months (ragdolls) and 5·9 months (Maine coons). Cats from more than 60 counties were represented for each breed. The difference between the expected and observed allele frequency was significant in Maine coons (P=0·047) but not in ragdolls (P=0·092). This is the first report of prevalence and demographics of the R820W and A31P mutations in ragdolls and Maine coons, respectively, in the British Isles. The prevalence is high, which is of relevance for breeding and screening programmes. The significant difference in genetic distribution may suggest early death of homozygous Maine coons. Show less