Hypertrophic cardiomyopathy in Maine Coon cats in The Netherlands The significance of the MYBPC3-A31P mutation and other known causative mutations, and the utility of N-terminal pro-brain natriuretic peptide in the diagnosis of this condition.

Abstract

Background: Hypertrophic cardiomyopathy (HCM) is the most common cardiomyopathy in cats and it is postulated to inherit as an autosomal dominant trait. Thus far, two mutations in the MYBPC3 gene are known. However, the relationship between genotype and phenotype is unclear. The gold standard test to diagnose HCM is echocardiography. However, this method has limited availability and is operator dependent. Measurement of N-terminal pro-brain natriuretic peptide (NT-proBNP) has been reported to be valuable in detecting HCM in cats. Objectives: The aims of this study were to fully phenotype Maine Coon cats from the Dutch population, to establish the phenotype-genotype correlation within these cats, and to measure NT-proBNP and compare these results with echocardiography as a screening test for the diagnosis of HCM Methods: Maine Coon cats (n=30) were classified using echocardiography as phenotypically healthy (n=19), or cats with an equivocal phenotype (n=3), or cats with HCM (n=8). Plasma NT-proBNP concentrations were measured in 33 Maine Coon cats. A total of 44 Maine Coon cats have been genotyped. Results: Based on echocardiography, 22 cats classified as healthy and eight as HCM. The HCM mutation A31P was found in four (66.7%) of the healthy cats, one of the equivocal cats (16.7%), and one (16.7%) of the HCM cats. The A74T mutation was found in twelve (80.0%) of the healthy cats and three (20.0%) of the HCM cats. HCM allele frequencies did not differ significantly between ‘healthy’ and ‘HCM’ groups (p=0.64 for A31P; p=0.54 for A74T). NT-proBNP concentrations ranged between <24 pmol/l and 278 pmol/l (median 31 pmol/l) in healthy cats and ranged between <24 pmol/l and >1500 pmol/l (median 197 pmol/l) in affected cats. The concentrations were significantly higher in affected cats compared to healthy cats (p=0.008). Conclusion: The value of genetic tests for detecting HCM is low in the cats of this study. The mutations analysed appear to have a low penetrance. NT-proBNP seems a promising cardiac biomarker in HCM, but more samples are needed.