Our Note:

This Articles are the newest results in the medical studies about the DNA testing in Maine Coon Cats. We always thought many breeders international are open for updates, but we see there is less information about how it is going on futuremore with the genetic testing. And what are we doing with the results? The Animal Univerity of Giessen gave a open Stament , the original text below. A second article of the german most well known Cardiologist, Dr. Jan-Gerd Kresken,, was translated into english, with a link to the original text. The articles were not changed in any way. Please note they were not written by back-yard-Vet's. Both, the Univerity of Giessen and the Dr. Jan-Gerd Kresken, areworiking together with international Univeritys and Cardiologist.



HCM

Article from Animal Univerity Giessen 06.02.2008

New to the HCM Gentest of the medicel small animal hospital of the Ludwig Maximilians universty in munchin was accomplished a study to two gene test on HCM,availale in germany,with maine Coons.The result shwos that the gene test does not bring anythimg.The study resulted in that Maine Coons with HCM are just as frequently positively tested in the gene test,as Maine Coons without HCM.

Therefore the investment is not worthwhile itself into a gene test simply.In the folling one we printed the result of the study,which was presented om the last weekend in the context of a lecture on a specialized congress for the animal medical profession in pouring.genetic association of the A31P-andA74T-Polymorphismen with the felinen hypertrophen Kardiomyopathie wlth the Maine Coon C.Schinner,K Weber,K.Hartmann,G.Wess, department for Cardiologie of the medical small animal of the Ludwig Maximilians university Munich introduction:The hypertrophe Cardiomyopathie (HCM) is the mostfrequent feline heart illness with autosomal dominantemhereditary course and varying Penetranz.The A31P-and A74T-Polymorphismen (SNPs) in the kardialen Myosin benig thing protein C3-Gen(MYBPC§) are regarded at present as causal mutations with Maine Coon cats.In practice ultrasonic diagnoses devitiatefrequently from the Genotyp.From breeders side as well as verterinary side is unclear,how with heart-healthy genotyp cats will proceed are.A goal of the study were therefore the evalution of the clinical association of both SNPs as well as the evaluation of the clinical validity of gene tests already marketed.material and methods:83 Maine Coon cats and 68 cats of different races entered study.Female animals had to be older as 36 months,older than 24 months.

The phenotyp"heart-healthy"or"HCM" had to be clear to assign.The Phaenotyping took place by means of heart ultrasonic,the Genotyping by means of tapman r Genotyping Asssays.Results:21,13% of the heart-healthy animal were positve in the gene test forthe A31P_and 32,84% for the A74T-SNP.75% of the HCM group carried the healthy allele concerning the A31P-and 50% concerning the A74T-SNPs.The allele frequencies did not differ between the groups ofphenotypes significantly.On the basis the available study population no reference existed that gene test already marketed prossess a praediktiven value.A computer-assisted protein analysis arranged the effect of the SNPs on the protein as beigne.The A31P Polymorphismus occurs also at other cat races.
Conclusions:With the examimed patient number no association was found between the HCM and the examined Polymorphismen.The gold standard for the breed selection exists further in the annual ultrasound investigation.





Cat heart,    March/2010
by Dr. Jan-Gerd Kresken, Cardiologist


Original taken http://www.hundkatzepferd.com/archive/789494/Katzenherzen.html

Hypertrophic cardiomyopathy (HCM, HCM) is the most common heart disease in cats. It is an acquired heart disease, which is genetically determined. Dr. Jan-Gerd Kresken reported on the current status for the diagnosis of HCM and the cat goes to the question of what genetic testing have brought four years.

The HCM usually occurs only when the cats are already breeding. In veterinary cardiology there are several ways to diagnose HCM in the cat. Besides the classical methods such as auscultation, X-ray, ECG, the echocardiogram has with its various technical options available, ranging from high-resolution two-dimensional images of the heart muscle via Doppler to tissue Doppler and strain analysis as a gold standard established.

Genetic Testing
These classical methods for the diagnosis of HCM were expanded in early 2006 to the genetic analysis. Initial research into the causative gene for HCM was the work of Dr. Kittleson, who postulated an autosomal dominant inheritance of the 1999 HCM in the Maine Coon with 100% penetrance. The American cardiologist Dr. Meurs and Dr. Kittleson found in 2005, the so-called A31P mutation (gene I) in the MYBPC3 gene in its American Maine Coon population. In 2007, Nyberg and colleagues further point mutation A74T (Gen II, Gen-cooking) at codon 74 of the cardiac MYBPC3 gene. Also in 2007, Dr. Meurs Ragdoll cats by DNA sequencing, a point mutation at codon 820 of the cardiac MYBPC3. There was a small group of 21 Ragdoll with the phenotypic diagnosis of HCM.

Facts about the state of affairs in genetic testing for HCM in the cat

Inheritance

- Autosomal dominant inheritance proved or suspected:
• Maine Coon
• American Shorthair
• British Shot hair
- Breed predispositions exist at:
• Maine Coon
• American and British Shorthair
• Norwegian and Siberian Forest Cat
• Persian
• Ragdolls
• Burman
• Turquoise Van
• Scottish Fold
• Sphynx

Gene mutations

- When the cat was on a gene (MYBPC3 cardiac), only three mutations described:
• A31P
• A74T
• R820W

Frequency of gene mutations in different countries

The studies by Dr. Kathryn Meurs, Washington State University, show that 33.6% of the Maine Coon population in the U.S. are carriers of a mutation A31P. In a study from our group in the cardiology-DKG DVG from 2007 it was determined that 30% of 119 heart-healthy Maine Coon cats were positive genetic test for the A31P-SNP. A recently published work of the University of Bristol showed a prevalence of A31P at 193 Maine Coon and Ragdoll cats R820W in 898, which was in both breeds at 30%. This means that the gene mutation in every third Maine Coon (A31P) or Ragdoll (R820W) is present.

Note: The presence of a mutation in a cat does not mean automatically that they will also suffer from a HCM! A few months after the launch of the first genetic tests and the large initial euphoria came to justifiable doubts as to the predictive power of genetic testing.

Relationship of genotype to phenotype of HCM: "There's something wrong."

There are two reasons

- Cats with homozygous test results (HCM / HCM) alive? Dr. Kittleson had described an autosomal dominant inheritance with 100% penetrance. Proof of this were the 33% of still-born kittens, which he suspected homozygous. A total of 45% of its population of HCM cats were diagnosed, of which he assumed they were therefore genetically heterozygous. The results within this family of cats were inconclusive. After the introduction of genetic testing, there was suddenly homozygous HCM cats that lived! This simple fact leads to the conclusion that the gene may have in these cats is not 100% penetrance or sufficient expressiveness.

- Genetically negative cats (N / N) are visible on ultrasound sick! In the four years we have seen regularly
phenotypically sick Maine Coon cats that had tested negative for both known genes. A recent publication of a remarkable woman Schinner from 2008 shows the doubts about the value of the local HCMGentests for cats.

A31P (Gen I)

83 Maine Coons from southern Germany were tested on the A31P mutation. 21.7% were tested positive, 78.3% negative. 83.3% were in the genetically positive but phenotypically negative ultrasound. Only 16.7% of the cats were genetically positive ultrasound also really concerned. Genetically tested negative by the Maine Coon 13.9% of HCM were diagnosed by ultrasound. Since the age of the animals was about 5 years, the numbers are certainly very representative.

Note: Only one in five in the genetic test positive cat was also heart-sick!

A74T (Gen II)

Here the figures are comparable. The A74T mutation was detected in 35.4% of the 79 Maine Coon. 78.6% of these cats included in the response to any inquiry HCM. The other way round: 76.5% of people suffering from HCM, Maine Coon cats carrying the normal allele G / G, indicating that be considered any further or other causal mutations or additional influences must.

Note: Three-quarters of people suffering from HCM cats were genetically inconspicuous!

Because of the A74T polymorphism (Gen II) of the MYBPC3 gene in this study as in other surveys as often happens in Maine Coon cats, as with other breeds, it can not be a Maine Coon-specific mutation. In addition, there is no amplification of the disease degree, if A31P (Gen I) may occur and A74T (Gen II) in an individual simultaneously. One can therefore assume that it is the HCM is a genetically complex disease.

Cardiac ultrasound

The echocardiogram (heart ultrasound) and its various application possibilities (Doppler, Tissue Doppler, strain and strain / rate) is the best method to detect cardiac muscle hypertrophy phenotype. Of course there are other cardiac procedures, listening to the heart of which is very important. The ECG and X-ray examination in the context of early detection of HCM rather useless. The ultrasound scan is very sensitive in the presence of hypertrophy, but can not exclude the diagnosis in cats with no genetic load and the subsequent occurrence.

Note: ECG and X-ray examination for the early detection of HCM rather unsuitable.

Basic precondition - alongside the experience of the examiner - are transducers with high resolution (7.5-10 MHz) and high frame rate. The hypertrophy may be represented as symmetric and asymmetric thickening of heart walls and papillary muscle. Almost always, only the left ventricle is affected. Diagnosis is based on the measurement of wall thickness in diastole, the phase of the cardiac muscle relaxation. First, the heart muscle in 2-dimensional image into multiple levels assessed. Then an M-mode measurements of diastolic wall thickness follows the defined standard levels. Is symmetrically distributed hypertrophy, the wall thickness increases can be measured and classified. Limit for a normal wall thickness is 5.5 mm. Between 5.5 and 6.0 mm, we speak of a doubtful (equivocal) findings. This has to do with the fact that there are two recommendations in the literature for the normal values ​​of heart walls in the cat.

Note: It is more difficult to measure asymmetric (local) or papillary muscle hypertrophy of the walls outside the standard levels and classify. Especially the experience of a specialized cardiologist is required.

The ultrasound examination of the heart to hypertrophy has a very high sensitivity. That is, if we see a significant wall thickening on ultrasound, then there is a hypertrophy. The hypertrophy is either the result of a primary genetic defect (HCM) or the secondary reaction to the blood pressure increase and / or hormonal changes. The secondary hypertrophy is almost always (directed equally to all cells to the inside) as concentric symmetrical thickening of all cells dar.

Recommendations for health care

The veterinary genetic research, despite respectable results, unfortunately, been unable to offer a genetic test that would be of value in breeding point of view. Of genetic testing can currently only testing for the gene mutation I (A31P) and suggest that even in Maine Coon cats from families who are related to the Maine Coon colony of Dr. Kittleson. These genetic tests (Gen I and II) for other breeds, which have increasingly HCM (see above) to perform, makes no sense. For breeding animals, the regular ultrasound examination of the heart is recommended. For legal reasons (§ 11b LPA) should therefore be started before the first breeding. Then we recommend a repeat in 1 - to 2-year intervals. The inspection intervals depend on the outcome.

Treatment of HCM

There is no drug that slows the tendency to hypertrophy. Since congestion, especially of the blood clotting and hypercoagulability are only visible by ultrasound, this study must be conducted therapy concomitantly.





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