My Opinion on the HCM gene test
Regular ultrasounds are important, just as important in my eyes is to take advantage of available genetic tests, to take cats out of breeding who carry a genetic mutation. The so far possible genetic test can't replace the HCM ultrasound, because there are other mutations that can cause HCM which can't be tested yet, and a cat's heart can have other diseases except HCM, which can be identified in the ultrasound. But the genetic test is a good tool in addition to the cardiac ultrasound in order to minimize the risk of HCM.
On many breeders pages you will find a summary of the Munich study (Schinner et al), but hardly mentioned are the two recent studies demonstrating the opposite, namely that the genetic test certainly helps in fighting against HCM!
The study published from Godiksen et al in 2011 shows that cats with homozygous form of A31P mutation develop HCM at a young age significantly more often than cats without the mutation. Cats with heterozygous form of A31P mutation have lower likelihood to develop HCM at early age (which does not exclude that they won't develop HCM in older age by this mutation). The study also points out that at the Munich study, the number of cats with homozygous mutation was too low (3 cats), to draw conclusions.
Also the 2010 published study by Mary et al concludes that the MYBPC3 A31P mutation is associated with a significantly increased risk for HCM.
I have compared the numbers of different studies quite impartially and contrast them here so everyone can see it for themself. How is the saying, "trust no study which you have not falsified yourself", for me the Munich study (Schinner) also shows a relationship between the mutation and the expression of HCM !
All data collections clearly show a significantly higher number of HCM positive ultrasound findings in cats that are homozygous for the A31P mutation, who can still deny a relationship between the mutation and HCM? The extent to which the mutation triggers HCM already in heterozygous cats is unclear, the figures suggest rather against. The reason for this could also be the incomplete penetrance, and that heterozygous cats would possibly develope a HCM only at higher age. But the fact that the mutation in homozygous form means a higher risk for HCM, is reason enough for me to avoid the mutation completely, and to breed only with mutation-free cats (n/n).
| Studies comparison | Godiksen | Mary | Schinner | Pawpeds | summarized numbers | ||||||
| total number MCO | 332 | 100,0% | 164 | 100,0% | 83 | 100,0% | 946 | 100,0% | 1525 | 100,0% | |
| Ultrasound positive of that | 21 | 6,3% | 12 | 7,3% | 12 | 14,5% | 63 | 6,7% | 108 | 7,1% | |
| Ultrasound equivocal of that | 26 | 7,8% | 0 | 0,0% | 0 | 0,0% | 28 | 3,0% | 54 | 3,5% | |
| Ultrasound negative of that | 285 | 85,8% | 152 | 92,7% | 71 | 85,5% | 855 | 90,4% | 1363 | 89,4% | |
| total ultrasound suspicious | 47 | 14,2% | 12 | 7,3% | 12 | 14,5% | 91 | 9,6% | 162 | 10,6% | |
| A31P negative | 226 | 100,0% | 109 | 100,0% | 65 | 100,0% | 699 | 100,0% | 1099 | 100,0% | |
| Ultrasound positive of that | 10 | 4,4% | 2 | 1,8% | 9 | 13,8% | 31 | 4,4% | 52 | 4,7% | |
| Ultrasound equivocal of that | 16 | 7,1% | 0 | 0,0% | 0 | 0,0% | 20 | 2,9% | 36 | 3,3% | |
| Ultrasound negative of that | 200 | 88,5% | 107 | 98,2% | 56 | 86,2% | 648 | 92,7% | 1011 | 92,0% | |
| total ultrasound suspicious | 26 | 11,5% | 2 | 1,8% | 9 | 13,8% | 51 | 7,3% | 88 | 8,0% | |
| A31P heterozygous | 88 | 100,0% | 48 | 100,0% | 15 | 100,0% | 223 | 100,0% | 374 | 100,0% | |
| Ultrasound positive of that | 2 | 2,3% | 5 | 10,4% | 2 | 13,3% | 21 | 9,4% | 30 | 8,0% | |
| Ultrasound equivocal of that | 8 | 9,1% | 0 | 0,0% | 0 | 0,0% | 7 | 3,1% | 15 | 4,0% | |
| Ultrasound negative of that | 78 | 88,6% | 43 | 89,6% | 13 | 86,7% | 195 | 87,4% | 329 | 88,0% | |
| total ultrasound suspicious | 10 | 11,4% | 5 | 10,4% | 2 | 13,3% | 28 | 12,6% | 45 | 12,0% | |
| A31P homozygous | 18 | 100,0% | 7 | 100,0% | 3 | 100,0% | 24 | 100,0% | 52 | 100,0% | |
| Ultrasound positive of that | 9 | 50,0% | 5 | 71,4% | 1 | 33,3% | 11 | 45,8% | 26 | 50,0% | |
| Ultrasound equivocal of that | 2 | 11,1% | 0 | 0,0% | 0 | 0,0% | 1 | 4,2% | 3 | 5,8% | |
| Ultrasound negative of that | 7 | 38,9% | 2 | 28,6% | 2 | 66,7% | 12 | 50,0% | 23 | 44,2% | |
| total ultrasound suspicious | 11 | 61,1% | 5 | 71,4% | 1 | 33,3% | 12 | 50,0% | 29 | 55,8% | |
| A31P positive (homo/hetero) | 106 | 100,0% | 55 | 100,0% | 18 | 100,0% | 247 | 100,0% | 426 | 100,0% | |
| Ultrasound positive of that | 11 | 10,4% | 10 | 18,2% | 3 | 16,7% | 32 | 13,0% | 56 | 13,1% | |
| Ultrasound equivocal of that | 10 | 9,4% | 0 | 0,0% | 0 | 0,0% | 8 | 3,2% | 18 | 4,2% | |
| Ultrasound negative of that | 85 | 80,2% | 45 | 81,8% | 15 | 83,3% | 207 | 83,8% | 352 | 82,6% | |
| total ultrasound suspicious | 21 | 19,8% | 10 | 18,2% | 3 | 16,7% | 40 | 16,2% | 74 | 17,4% | |
Anyone interested can find the studies behind these numbers at the following links:
Hypertrophic cardiomyopathy in young Maine Coon cats caused by the p.A31P cMyBP-C mutation - the clinical significance of having the mutation (Mia TN Godiksen, Sara Granstrøm, Jørgen Koch and Michael Christiansen) 2011
Prevalence of the MYBPC3-A31P mutation in a large European feline population and association with hypertrophic cardiomyopathy in the Maine Coon breed (Jerome Mary, Valerie Chetboul, Carolina Carlos Sampedrano, Marie Abitbol, Vassiliki Gouni, Emilie Trehiou-Sechi, Renaud Tissier, Guillaume Queney, Jean-Louis Pouchelon, Anne Thomas) 2010
Genetische Assoziation der A31P- und A74T-Polymorphismen im kardialen Myosin-binding-protein-C-Gen mit der felinen familiären hypertrophen Kardiomyopathie bei Maine-Coon-Katzen (Schinner et al) 2008
Basics about the genetic tests
A31P-Mutation
In 2005, the research group led by Kathryn Meurs at Ohio State University in Ohio / USA could identify a gene mutation in the myosin binding protein C (MYBPC3). 16 HCM diseased Maine coon cats and 107 HCM free cats were examined for the presence of this mutation. The mutation was found in all 16 diseased cats, but in none of the 107 healthy cats. Because of this, the conclusion could be drawn that this mutation in the MYPBC3 gene is a trigger of primary hypertrophic cardiomyopathy in Maine Coon cats. Genetic tests on this A31P mutation is available since end of 2005.
A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy (Kathryn M. Meurs, Ximena Sanchez, Ryan M. David, Neil E. Bowles, Jeffrey A. Towbin, Peter J. Reiser, Judith A. Kittleson, Marcia J. Munro, Keith Dryburgh, Kristin A. MacDonald and Mark D. Kittleson)
A74T-Mutation
In the summer of 2007 the group led by Jørgen Koch discovered a further mutation in the gene MYBPC3: A74T. However, this genetic test was never officially released on the market since Jørgen Koch could not confirm the relationship between the gene and HCM.
Intra-allelic Genetic Heterogeneity of Hypertrophic Cardiomyopathy in the Maine Coon Cat
(Mia Titine Nyberg, Jørgen Koch, Michael Christiansen)
© This text is written by Britta Singethan.
It can published on other sites, with a reference to the author and a link to this homepage.
