Inherited disorders in cats

Inherited disorders are conditions that result from abnormal genes passed down from one generation to the next. Some genetically determined disorders are obvious at birth, while others may not develop (or may not be obvious) until later in life. 

Common and/or important inherited disorders in cats  

Some of the more common inherited disorders of cats include: 

• α-Mannosidosis 

• Burmese Head Defect  

• Deafness  

• Devon Rex Myopathy  

• Gangliosidosis  

• Glycogen storage disease type IV 

• Hypertrophic cardiomyopathy  

• Hypertrophic muscular dystrophy  

• Hypokalaemic polymyopathy  

• Manx syndrome (spina bifida)  

• Mucopolysaccharidosis 

• Niemann-Pick Disease (sphingomyelinosis)  

• Osteochondrodysplasia or Scottish Fold disease  

• Polycystic kidney disease  

• Polydactyl cats 

• dProgressive retinal atrophy  

• Pyruvate kinase deficiency  

• Spinal muscular atrophy in Maine Coons  

There are many other inherited diseases, seen less often. Some pedigree cats have been deliberately bred and selectively developed for extreme traits or characteristics. These are all traits which can be passed down through generations, and where these compromise the health or welfare of a cat, International Cat Care believe such traits or mutations should not be continued through further breeding.  

Examples include: 

• Severe brachycephalic in Persians and similar breeds  

• Hairless cats 

• Short-legged cats 

Certain diseases are more common in specific breeds or lines within breeds, suggesting a genetic predisposition. This shows that the disease is likely inherited, although the specific genes involved have not been identified in many cases.  

Examples of this include:  

• Feline orofacial pain syndrome in Burmese cats 

• Diabetes mellitus in Burmese cats 

• Asthma in Siamese and related cats 

• Flat-chested kittens in Burmese cats  

• Mediastinal lymphoma in Siamese cats  

• Patellar luxation  

• Hip dysplasia 

• Pyloric stenosis or dysfunction in Siamese cats  

• Amyloidosis 

• Small intestinal adenocarcinoma in Siamese cats  

• Strabismus (squint, cross-eyed) in Siamese cats 

Are some breeds genetically ‘healthier’ than others? 

It’s impossible to say that some breeds are genetically ‘healthier’ than others. In some breeds, a variety of inherited diseases have been identified, but this is often due to more monitoring and testing within these breeds. It doesn’t necessarily mean they have a higher frequency of inherited diseases. 

An exception to this is where an inherited disorder is specifically bred for within a breed, but is also detrimental to the health of the cat. Obvious examples of this include the breeding of Manx cats, Scottish Folds, and extreme-type (very flat-faced) Persians. In these cats, the characteristic of the breed itself is based on gene mutations or selecting genotypes that express a trait or appearance (phenotype)that is harmful to the health of the cat. 

Can inherited diseases be controlled? 

Where inheritance is simple and where there’s a DNA test widely available, controlling an inherited disease can be straightforward.  

A good example of controlling an inherited disease is polycystic kidney disease (PKD) in Persian cats and related breeds. In the past, up to 50% or more of Persian cats may have been affected by this disease, which frequently results in chronic kidney disease and premature death of affected cats. 

Cats with PKD can now be easily identified using an accurate DNA test (performed on a blood sample or cheek swab), and breeding from them can be prevented. Because of this, in many countries, the frequency of PKD has now been dramatically reduced. 

What precautions should be taken when doing DNA testing for a breeding programme? 

When DNA testing cats (to determine whether they are suitable for a breeding programme) a vet should always be present to supervise, and a reputable and reliable testing laboratory should be used. 

International Cat Care believe that whenever genetic tests are run on cats for the selection of breeding stock, the gene test result should be linked to some form of permanent identification of the cat that has been tested (eg, a standard, internationally recognised microchip number), and that a vet should collect the sample (blood sample or cheek swab) so that the identification (microchip number) can be verified and recorded on the submission form and result. 

Additional considerations 

Genetic testing of cats 

Recent advances in genetic investigation and testing mean it’s been possible to identify the gene defects associated with several inherited conditions, confirm their genetic basis, and in many cases, develop diagnostic tests to identify affected cats (and occasionally ‘carrier’ cats). 

With different cat populations in different parts of the world, some genetic disorders may be seen more commonly, or even exclusively, in some locations. However, with international travel of both owners and cats, many disorders are seen worldwide (although the frequency of disease may vary in different regions). 

Many different veterinary laboratories offer genetic (DNA) tests for different diseases and your vet will be able to discuss those available with you.