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Welcome To Mountain Fork Maine Coons
Small Epic Cattery. Big European Cats.
Located In Broken Bow, OK USA
Maine Coon HCM, SMA, PKD1, PK Deficiency, PRA-CRX, PRA-CEP 290, Mucopolysaccharidosis VI
Mountain Fork Participates In DNA Genetic Testing For Diseases Affecting The Maine Coon Breed
100% European Maine Coons Are Our Passion.
Responsible Breeding For Health & Longevity Is A Top Priority!
 
Per the website of Veterinary Genetics Lab (vgl) University of California (UC Davis) Veterinary Medicine:
 
Mucopolysaccharidosis VI (MPSVI)

Introduction

Mucopolysaccharidosis VI severe (MPSVIs) and mild (MPSVIm) are lysosomal storage diseases resulting from two independent mutations in the gene for enzyme N-acetylgalactosamine 4-sulfatase (4S).  Both are inherited as autosomal recessives, thus males and females can be equally affected if they carry 2 copies of the defective gene. Cats with 2 copies of the severe form show signs at 6-8 weeks of age that include wide faces, shortened noses, small ears, reduced flexibility and retarded growth compared to unaffected littermates.  By 8 months of age, problems of severe hind-limb mobility or paralysis, and signs of degenerative joint disease can be observed. Clinically, urine samples show increased levels of dermatan sulfate (DS) and an increase in white blood cell granules.  Organs and tissues can also be compromised by accumulation of intercellular DS. Additional effects of the disease include corneal clouding and heart valve thickening. Cats with two copies of the mild form disease (MPSVIm) have less 4S enzyme and form granules in the white blood cells but otherwise appear healthy.  The same is true of cats with one copy of the mild form and one copy of the severe form. Cats with only one copy (carrier) of either mutation and one copy of the normal gene appear healthy.  Breeding two carriers together is predicted to produce 25% affected offspring and 50% carriers of the disease. Breeds at risk for MPSVIs and MPSVIm are Birman, Ragdoll, Siamese and related breeds, Domestic Shorthair.

The VGL offers DNA tests for MPSVIs and MPSVIm to assist owners and breeders in identifying affected and carrier cats. The tests are done with DNA collected from buccal swabs thus avoiding invasive blood collection.

Results reportd as:

Test Result MPSVIs and MPSVIm
N/N Normal, cat does not have either MPSVIs or MPSVIm mutations
N/MPSVIs Carrier, cat has one copy of MPSVIs mutation but is normal
N/MPSVIm Carrier, cat has one copy of MPSVIm mutation but is normal
MPSVIs/MPSVIs

Affected, cat has 2 copies of MPSVIs (severe form)

MPSVIm/MPSVIm

Affected, cat has 2 copies of MPSVIm (mild form)

MPSVIs/MPSVIm

Cat has one copy each of MPSVIs and MPSVIm but may be otherwise healthy

References:

Yogalingam G, T Litjens, J Bielicki et al. 1996. Feline mucopolysaccharidosis type VI. Characterization of recombinant N-acetylgalactosamine 4-sulfatase and identification of a mutation causing the disease. J. Biol. Chem. 271(44): 27259-27265.

Yogalingam G, JJ Hopwood, A Crawley & DS Anson. 1998. Mild feline mucopolysaccharidosis type VI. Identification of an N-acetylgalactosamine 4-sulfatase mutation causing instability and increased specific activity. J. Biol. Chem. 273(22):13421-13429.

Crawley AC, G Yogalingam, VJ Muller & J Hopwood. 1998. Two mutations within a feline mucopolysaccharidosistType VI colony cause three different clinical phenotypes. J. Clin. Invest. 101(1):109-119.

PKD1 (Polycystic Kidney Disease) in Felines
Introduction

Polycystic Kidney Disease (PKD) is a well documented abnormality in domestic cats. Cystic kidneys can sporadically occur in any population of cats. PKD is not a new disease and has been reported in the literature for over 30 years. The heritable form of PKD1 may not have initially occurred in Persians as a new mutation, but perhaps in random bred cats. Unfortunately, PKD1 does not have a strong clinical presentation. The presentation of PKD1 is similar to one of the most common causes of death for any cat, renal failure. Thus, PKD1 has gone unnoticed for many years and has spread throughout the Persian breed. Any breed that has used Persians in their foundation or propagation should have concerns for PKD1.

In Persians, the condition has been shown to be inherited as a single autosomal dominant gene. It is estimated over 37% of Persians have PKD1, a breed that accounts for nearly 80% of the cat fancy. Many lines and catteries have been able to greatly reduce this frequency by using ultrasound screening methods and improved breeding practices.

Detailed PKD1 Information

Genetics and Inheritance

Early onset, bilateral presentation (both kidneys), and multiple cysts are all traits of the heritable form of the disease. The kidney cysts for PKD1 present early, often before 12 months of age. Renal failure, however, usually occurs at a later age. Thus, PKD1 is considered a late onset renal disease. In the fancy cat breeds, PKD1 is inherited as an autosomal dominant condition. This implies that one copy of the gene is required to produce PKD1. Generally, 50% of PKD1 positive cats' offspring will inherit PKD1. A positive cat could potentially be homozygous for PKD1 and all offspring produced would have PKD1. It is suspected that cats that are homozygous for PKD1 are not abundant and the homozygote form could be lethal in utero or severely present at a very early age. Further research is required to prove the effects of the homozygote condition.

Sections reprinted with permission of: Leslie A. Lyons Ph.D., Assistant Professor,

 
Erythrocyte Pyruvate Kinase Deficiency
(PK Deficiency) in Felines
Introduction

Erythrocyte Pyruvate Kinase Deficiency (PK Deficiency) is an inherited hemolytic anemia caused by insufficient activity of this regulatory enzyme which results in instability and loss of red blood cells. The anemia is intermittent, the age of onset is variable and clinical signs are also variable. Symptoms of this anemia can include: severe lethargy, weakness, weight loss, jaundice, and abdominal enlargement. This condition is inherited as an autosomal recessive.

Based on a survey of 38 breeds, the mutation responsible for PK deficiency has been found in significant frequency in Abyssinian, Bengal, Domestic Shorthair and Longhair, Egyptian Mau, La Perm, Maine Coon, Norwegian Forest, Savannah, Siberian, Singapura and Somali. Cats of these breeds are at higher risk of having PK deficiency or producing affected offspring; genetic screening for the mutation is recommended. A few breeds showed very low frequency of the mutation (less than 0.2%) and are low risk: Exotic Shorthair, Oriental Shorthair and Persian.

The VGL offers a DNA test for PK deficiency to assist owners and breeders in identifying affected and carrier cats. The test uses DNA collected from buccal swabs avoiding invasive blood collection. Breeders can use this test as a tool to avoid breeding carriers together which would produce 25% affected offspring.

 

Results are reported as:

Test Result PK deficiency status
N/N no copies of PK deficiency, cat is normal
N/K 1 copy of PK deficiency, cat is normal but is a carrier.
K/K 2 copies of PK deficiency, cat is or will be affected. Severity of symptoms cannot be predicted.

 

Reference:
Grahn RA, Grahn JC, Penedo MCT, Helps CR, Lyons LA. Erythrocyte Pyruvate Kinase Deficiency Mutation Identified in Multiple Breeds of Domestic Cats. BMC Veterinary Medicine 2012 (in press).

Progressive Retinal Atrophy in Felines

Introduction

In Abyssinian, Somali and some Ocicat breeds, an inherited late-onset blindness condition has been identified and is characterized by progressive degeneration of the photoreceptors (rods and cones) in the retina.  This disease has been designated "rdAc".  Cats affected with this form of blindness have normal vision at birth, with degeneration first detected by electroretinographic (ERG) exam at about seven months of age.  Vision loss progresses slowly and is variable, with most cats becoming blind by usually 3-5 years of age.  There is no treatment available for the condition.  This is an autosomal recessive condition, thus the disease is not associated with gender and two copies of the mutation are required for the cats to lose their vision.  Carriers, cats that have one copy of the mutation, are not affected and have normal vision.

A single nucleotide mutation in the gene called CEP290 produces a defective protein which is associated with this progressive retinal atrophy (PRA) in the cat.  In addition to Abyssinian, Somali and Ocicat, a survey of 43 cat breeds showed presence of the CEP290 mutation in many other breeds including, American Curl, American Wirehair, Bengal, Balinese/Javanese, Colorpoint Shorthair, Cornish Rex, Munchkin, Oriental Shorthair, Peterbald, Siamese, Singapura and Tonkinese. The high frequency of the CEP290 mutation in Siamese (about 33%) and related breeds (Oriental Shorthair, Balinese/Javanese, Colorpoint Shorthair, Peterbald) poses a significant health risk in the Siamese breed group.

A different form of blindness called “rod cone dysplasia”, or “Rdy” has also been identified in Abyssinian and Somali cats. The mutation is a single base pair deletion in a different gene, CRX, which also results in a defective protein that is critical for eye development.  Cats carrying one copy of this mutation have retarded development and degeneration of photoreceptor cells, which leads to early-onset blindness by 7 weeks of age. Current information suggests that the “Rdy” mutation is restricted to the Abyssinian and Somali breeds. The “Rdy” mutation is inherited as a dominant trait. Cats that have one or two copies of the mutation will be affected. The Rdy mutation is rare.

To assist owners and breeders in identifying affected and carrier cats, the VGL offers DNA tests for the two mutations known to cause the two different forms of PRA in cats - rdAc (CEP290) and Rdy (CRX).  The tests use DNA collected from buccal swabs.  Breeders can use these tests as tools to avoid breeding two carriers of rdAc which would produce 25% affected offspring, or to test for the presence of “Rdy” in the CRX gene of suspected affected cats.

Since both forms of blindness are found in the Abyssinian breed, all associated breeds may have a concern for these diseases.  The two mutations (rdAc and Rdy) have been tested in a novel form of blindness in the Bengal cat, and both have been excluded from causing the Bengal cat blindness (LA Lyons, personal communication).  Since Bengal cats have had Abyssinian breedings in their ancestry, these genetic tests may be warranted in some Bengal lines.

 

Results reported as:

Test Result CEP290 PRA-rdAc Status
N/N Normal, cat does not have rdAc mutation*
N/rdAc Carrier, cat has one copy of rdAc mutation. Breedings between carriers will be expected to produce 25% affected kittens.
rdAc/rdAc Affected

* This test only detects the mutation in the CEP290 gene known to cause PRA in Abyssinian, Somali, Ocicat and other breeds mentioned above.

Test Result CRX PRA-Rdy Status
N/N Normal, cat does not have Rdy mutation**
N/Rdy Affected, cat has one copy of the Rdy mutation. This cat will produce affected kittens 50% of the time when bred to a normal cat, or 75% of the time when bred to another cat with one copy of the Rdy mutation.
Rdy/Rdy Affected, cat will always produce affected kittens.

** This test only detects the mutation in the CRX gene known to cause PRA in Abyssinian and Somali breeds.

References:

Menotti-Raymond M, David VA, Schäffer AA, Stephens R, Wells D, Kumar-Singh R, O'Brien SJ, Narfström  K. Mutation in CEP290 discovered for cat model of human retinal degeneration. J. Hered. 2007 May-Jun; 98(3):211-20. Epub 2007 May 16. PubMed PMID: 17507457.

Menotti-Raymond M, Deckman KH, David V, Myrkalo J, O'Brien SJ, Narfström K. Mutation discovered in a feline model of human congenital retinal blinding disease. Invest Ophthalmol Vis Sci. 2010 Jun; 51(6):2852-9. Epub 2010 Jan 6. PubMed PMID: 20053974.

Menotti-Raymond M, David VA, Pflueger S, Roelke ME, Kehler J, O'Brien SJ, Narfström K. Widespread retinal degenerative disease mutation (rdAc) discovered among a large number of popular cat breeds. Vet J. 2009 Sep 9. [Epub ahead of print] PubMed PMID: 19747862.

Spinal Muscular Atrophy in Maine Coon Cats

Introduction

Spinal Muscular Atrophy (SMA) is a genetic disease seen in Maine Coon cats. The disease is characterized by progressive instability with unsteady gait and posture abnormalities due to loss of motor neurons in the lower spinal cord and atrophy of muscles in the hind limbs. Affected kittens first show signs of SMA at about 3-4 months of age. The condition is neither painful nor fatal and affected cats can live a comfortable life indoors. The disease is inherited as an autosomal recessive, thus 2 copies of the mutation are required to produce the disease and both males and females are equally affected.  SMA in Maine Coon cats is caused by a large deletion of chromosome 1.

Procedure for collecting a feline DNA sample

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Allow 2-6 business days for results.

The VGL offers a test to identify both affected kittens and carriers. Genetic testing assists breeders to avoid future matings that can produce affected kittens.

Results reported as:

Test Result Spinal Muscular Atrophy Status
N/N No copies of SMA are present.
N/S

1 copy of SMA is present. Cat is normal but is a carrier. Breeding between carriers will be expected to produce 25% affected, 50% carriers and 25% normal kittens.

S/S

2 copies of SMA are present, cat is affected.

Reference:

Fyfe J.C., M Menotti-Raymond, VA David, et al. An ~140-kb deletion associated with feline spinal muscular atrophy implies an essential LIX1 function for motor neuron survival. Genome Research 2006 16: 1084-1090.

Hypertrophic Cardiomyopathy - HCM

Introduction

Hypertrophic Cardiomyopathy is the most common cardiac disease in cats. Affected cats are at risk of sudden cardiac death due to defects that produce increased left ventricular heart muscle thickness. In the Maine Coon breed, the A31P mutation in the cardiac myosin binding protein C gene (MYBPC3) has been found to be associated with increased risk for HCM. See below for a summary of published research on HCM and Maine Coon cats.

Maine Coon HCM

The A31P breed specific mutation for inherited HCM in Maine Coon cats produces moderate to severe cardiac disease which can lead to sudden death by age 4 years or less for cats that carry two copies of the mutation (homozygotes). Cats that carry one copy of the mutation (heterozygotes) have a longer life expectancy, but may still develop HCM. The mutation is a single base pair change in MYBPC3 that disrupts the production of the cardiac myosin binding protein C needed for normal heart muscle development.

The Veterinary Genetics Laboratory offers a test for the Maine Coon breed specific HCM mutation.

Results reported as:

Test Result Maine Coon HCM Status
N/N Normal
N/HCMmc

One copy of the A31P mutation is present. Cat is 1.8 times more likely to develop HCM than cats without the mutation.

HCMmc/HCMmc

Two copies of the A31P mutation are present. Cat is 18 times more likely to develop HCM than cats without the mutation.

Note: This test only detects the A31P mutation associated with HCM in Maine Coon cats and their outcrosses as described by Meurs et al. 2005. Test performed under license from University of California, Davis.

References for A31P mutation:

Meurs K., X. Sanchez, R.M. David, N.E. Bowles, J.A. Towbin, P.J. Reiser, J.A. Kittleson, M.J. Munro, K. Dryburgh, K.A. MacDonald, M.D. Kittleson. A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy. Human Molecular Genetics (2005) Vol.14, No. 23, doi:10.1093/hmg/ddi386.

Summary of published research regarding A31P mutation and Maine Coon HCM (by N.C. Pedersen, DVM, PhD)

A number of papers dealing with the significance of the MYBPC3-A31P mutation in Maine Coons have recently been published.  The data from these publications (referenced below), when analyzed collectively, have allowed a better understanding of the importance of this mutation in causing hypertrophic cardiomyopathy (HCM). This particular mutation has been found almost exclusively in the Maine Coon breed.  About 63% of Maine Coon cats that were genetically tested but not clinically phenotyped (no echocardiographic imaging) for HCM were free from the mutation.  This figure was 70% for cats that were both genetically tested and clinically phenotyped for HCM.  The overall percentage of cats carrying one copy of the mutation (heterozygotes) was 34% in the non-phenotyped population and 26% among the phenotyped cats. The incidence of cats carrying two copies of the mutation (homozygotes) was 3% in non-phenotyped cats and 4% in phenotyped cats.  Therefore, it is relatively certain that about two thirds of Maine Coons around the world are free of the mutation, and one third of them have one or two copies of the mutation. Two copies of the A31P mutation appear to cause considerable embryonic death based on the observed deficit of homozygotes, i.e., 7-16% homozygotes were expected but only 3-4% observed.

The mutation does not appear to behave as a simple dominant trait, but rather as a dominant trait with incomplete penetrance.   The relative risk (RR) for HCM in cats carrying one copy of the A31P mutation is around 1.8 compared to cats that do not have the mutation.  However, the relative risk for HCM in cats carrying two copies of A31P is around 18.   Therefore, cats with one copy of the mutant allele are 1.8 times more likely to develop HCM than cats carrying normal alleles. Cats with two copies of the mutant allele are 18 times more likely to develop HCM than cats carrying normal alleles and 10 times more likely to develop HCM than cats with one copy of the mutant allele

These studies have also identified HCM in cats that do not carry the MYBPC3-A31P.  The incidence of HCM in these studies was 5.4% in cats that were negative for the A31P mutation, and 5.4% with the mutation.  Therefore, the MYBPC3-A31P mutation is not the sole cause of HCM in Maine Coons.  The other causes are not known at this time.

Additional information from these publications suggests that male cats may be twice as likely to be affected as females, and that heavier cats are more prone to develop HCM than lighter cats.  However, this latter relationship may itself be attributable to a larger size for males than females. One study also suggested that more heterozygous cats may develop disease as they get older (>4 years), but this has yet to be convincingly proven, and most cases of clinical HCM still occur before 4 years of age.  Nevertheless, the possible influence of such as factors as gender, weight and age indicates that non-genetic factors also contribute to overall disease risk. 

Differences in results between these various studies can be attributed to a number of factors, probably the most important being sample size.  Another factor concerns phenotyping.  The criteria for judging whether a cat has HCM or not are not precise, leading one of the studies to classify cats as either normal, equivocal, or affected.   The incidence and risk estimates given above were based on cats that were clearly normal or affected; cats that were graded as equivocal were not included.  

Given the increased knowledge that has come forth from many sources, the VGL offers the MYBPC3-A31P mutation test for hypertrophic cardiomyopathy in Maine Coon cats.  Hopefully, breeders will be able to use this information to improve the vigor of the breed.  A better understanding of test results will also contribute to a more realistic appraisal of the value of the test in breed improvement.

References reviewed

1. Godiksen M, et al. Hypertrophic cardiomyopathy in young Maine Coon cats caused by the p.A31P cMyBP-C mutation – the clinical significance of having the mutation. Acta Veterinaria Scandinavica 53:7-18, 2011.

2.  Mary J, et al. Prevalence of the MYBPC3-A31P mutation in a large European feline population and association with hypertrophic cardiomyopathy in the Maine Coon breed. J. Vet. Cardiology 12:155-161, 2010.

3.  Wess G, et al. Association of A31P and A74T Polymorphisms in the Myosin Binding Protein C3 Gene and Hypertrophic Cardiomyopathy in Maine Coon and Other Breed Cats. J. Vet. Internal Med. 24:527-532, 2010.

4. Fries R, et al. Prevalence of the Myosin-binding Protein C Mutation in Maine Coon Cats. J. Vet. Internal Med. 22:893-896, 2008.

 
 

 

 

 

Est. 2005

Email: nursekelly70@yahoo.com    Text (580) 306-3571

Kelly Sparkman, Founder, Mountain Fork European Imports, LLC    

Updated September 18, 2020