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Maghreb´s Abessinier & Ocicat
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LIST OF ARTICLES
Menotti-Raymond, M., V. DAVID, et al. (2007). "Mutation in CEP290 Discovered for Cat Model of Human Retinal Degeneration." J. of Heredity: doi:10.1093/jhered/esm019.
Rah, H., D. J. Maggs, et al. (2006). "Lack of genetic association among coat colors, progressive retinal atrophy and polycystic kidney disease in Persian cats." J Feline Med Surg 8(5): 357-60. An inherited form of progressive retinal atrophy (PRA) is recognized in Persian cats; however, the prevalence of PRA in the breed has not been determined. Breeders suggest that cats from only brown ('chocolate') or Himalayan ('pointed') lines are at risk for PRA, suggesting the disease is not widespread. This study was designed to evaluate whether PRA in Persian cats is associated with three coat colors, including chocolate, or with a highly prevalent inherited disease in this breed--polycystic kidney disease (PKD). Sixty related cats were evaluated for PRA by ophthalmic examination and genetically typed for PKD and the mutations that cause coat color variants in agouti, brown and color (producing the pointed coloration in Himalayan). No associations were identified among any of the traits, including between PRA and chocolate. These data suggest that PRA is not limited to cats with chocolate coat coloration and breeders and veterinarians should be aware that the prevalence of the disease may be higher than currently claimed.
Glaze, M. B. (2005). "Congenital and hereditary ocular abnormalities in cats." Clin Tech Small Anim Pract 20(2): 74-82. Congenital and inherited ocular diseases are reported less frequently in the cat than the dog. The 2 species also differ in their array of disorders, with familiar canine abnormalities like cataracts overshadowed by unique feline diseases such as eyelid agenesis and corneal sequestration. Organized according to the primary ocular structure affected and commingling congenital and inherited disorders in each section, the review begins with multiple ocular anomalies and their impact on globe-orbit relationship. Adnexal disorders include eyelid agenesis, entropion, dermoid, and nictitans gland protrusion. Corneal abnormalities range from the routine sequestrum and PPM-related opacity to those rare infiltrates accompanying inborn errors of metabolism. Brief descriptions of uveal anomalies, primary glaucoma, cataracts, and lens luxations follow. Retinal dysplasia and progressive retinal atrophy complete the summary. Suspicions of heritability are often based on small numbers of animals in sporadic reports of ocular disease, but the Persian, Burmese, and Siamese are among the breeds repeatedly linked with one or more of these disorders.
Rah, H., D. J. Maggs, et al. (2005). "Early-onset, autosomal recessive, progressive retinal atrophy in Persian cats." Invest Ophthalmol Vis Sci 46(5): 1742-7. PURPOSE: An early-onset retinal degenerative disease has been identified in Persian cats. This study genetically, clinically, and histologically characterized the disease. A breeding colony was established to assist with identification of the causative gene and to provide a resource for vision research. METHODS: Cats were produced from testcross breedings. Kittens underwent serial ophthalmic and neuro-ophthalmic examinations. Globes were harvested from age-matched affected, obligate carrier, and control cats and were evaluated by light microscopy. Fluorescein angiography assessed retinal and choroidal vasculature. RESULTS: Test breedings confirmed an autosomal recessive mode of inheritance. Rate and extent of disease progression were similar among individual affected cats. The earliest clinical signs (reduced pupillary light reflexes) were seen at 2 to 3 weeks of age. Retinal degeneration was virtually complete by 16 weeks of age. Histologic changes progressed rapidly and paralleled clinical findings. Histologic lesions were limited to the photoreceptors, outer plexiform layer, and retinal pigment epithelium in all but the terminal stages, when subtle changes were noted within the inner nuclear layer. CONCLUSIONS: Characterized in this study was an autosomal recessive, early-onset, retinal degenerative disease in Persian cats that is likely to be more prevalent in this breed than previously suspected. This feline disease model may identify a new gene or provide biological insight into some forms of early-onset retinitis pigmentosa (RP) in humans and genetic retinal degenerations in other species. A breeding colony that will assist in the identification of the causative gene has been established and is available for studies in vision research.
Djajadiningrat-Laanen, S. C., M. M. Vaessen, et al. (2002). "[Progressive retinal atrophy in Abyssinian and Somali cats in the Netherlands (1981-2001)]." Tijdschr Diergeneeskd 127(17): 508-14. From 1981 to 2001, 248 Abyssinian and 127 Somali cats in the Netherlands were examined for hereditary eye disease. Distinct ophthalmoscopic signs consistent with hereditary progressive retinal atrophy (PRA) were observed in 11 Abyssinian cats, and subtle signs in 3 Abyssinian cats. A familial relationship was detected in 13 out of 14 of these cats, which supports a hereditary basis to the condition. Distinct funduscopic signs of retinal degeneration were observed at a median age of 4 years. One cat with advanced retinal degeneration was only 7 months old, whereas the remaining 10 cats were between 2 and 12 years old at the time of diagnosis. These differences in the age of onset are suggestive of at least two types of PRA occurring in Abyssinian cats in the Netherlands: a dysplastic, early-onset and a late-onset retinal degeneration. A large-scale and systematic examination programme for hereditary eye disease will be necessary to assess the incidence of PRA in the Dutch population of Abyssinian and Somali cats as a whole, and to provide a basis for a preventive breeding programme.
Nilsson, S. F., O. Maepea, et al. (2001). "Ocular blood flow and retinal metabolism in abyssinian cats with hereditary retinal degeneration." Investigative Ophthalmology & Visual Science 42(5): 1038-44. PURPOSE: To investigate if retinal blood flow decreases with progression of the disease in Abyssinian cats with progressive retinal atrophy (PRA), to examine if the choroidal blood flow was affected by the disease, and to determine the uptake of glucose and formation of lactate in the outer retina. METHODS: Local blood flow in different parts of the eye was determined with radioactive microspheres, in 9 normal cats and in 10 cats at different stages of PRA. Three blood flow determinations were made in each animal, during control conditions, after IV administration of indomethacin and after subsequent administration of N(omega)-nitro-L-arginine (L-NA). Blood samples from a choroidal vein and a femoral artery were collected to determine the retinal formation of lactate and uptake of glucose. RESULTS: In Abyssinian cats with PRA (n = 10), the retinal blood flow was significantly (P < or = 0.01) lower than in normal cats (n = 9) during control conditions, 6.4 +/- 1.7 compared with 14.1 +/- 1.9 g min(-1) x (100 g)(-1). The vascular resistance in the iris and ciliary body was significantly higher in the cats at a late stage of PRA, both compared with normal cats and to cats at an early stage of the disease, whereas the choroidal vascular resistance was not significantly affected. Indomethacin had no effect on ocular blood flows in normal cats, but in cats with PRA, iridal blood flow was more than doubled after indomethacin. The retinal formation of lactate was significantly (P < or = 0.001) lower in cats with PRA than in normal cats, 0.111 +/- 0.035 (n = 8) compared with 0.318 +/- 0.024 (n = 8) micromol x min(-1). The uptake of glucose was not significantly different in cats with PRA. CONCLUSIONS: Retinal blood flow is severely decreased in Abyssinian cats at a late stage of retinal degeneration, whereas the choroidal microcirculation is not significantly affected by the disease. At a late stage of retinal degeneration, vascular resistance in the iris is significantly increased, which at least in part could be caused by cyxlooxygenase products. [on SciFinder (R)]
Runte, M., G. Dekomien, et al. (2000). "Evaluation of RDS/Peripherin and ROM1 as candidate genes in generalised progressive retinal atrophy and exclusion of digenic inheritance." Anim Genet 31(3): 223-7. Generalised progressive retinal atrophy (gPRA) is a heterogeneous group of hereditary diseases causing degeneration of the retina in dogs and cats. As a combination of mutations in the RDS/Peripherin and the ROM1 genes leads to the phenotype of retinitis pigmentosa in man we first performed mutation analysis to screen these genes for disease causing mutations followed by the investigation of a digenic inheritance in dogs. We cloned the RDS/Peripherin gene and investigated the RDS/Peripherin and ROM1 genes for disease causing mutations in 13 gPRA-affected dog breeds including healthy animals, obligate gPRA carriers and gPRA-affected dogs. We screened for mutations using single strand conformation polymorphism (SSCP) analysis. Sequence analysis revealed several sequence variations. In the coding region of the RDS/Peripherin gene three nucleotide exchanges were identified (A277C; C316T; G1255A), one of which leads to an amino acid substitution (Ala339Thr). Various silent sequence variations were found in the coding region of the ROM1 gene (A536G, G1006A, T1018C, T1111C, C1150T, C1195T), as well as an amino acid substitution (G252T; Ala54Ser). By excluding the respective gene as a cause for gPRA several sequence variations in the intronic regions were investigated. None of these sequence variations cosegregated with autosomal recessively (ar) transmitted gPRA in 11 breeds. The candidate gene RDS/Peripherin obviously does not harbour the critical mutation causing the autosomal recessive form of gPRA because diseased individuals show heterozygous genotypes for sequence variations in the Miniature Poodle, Dachshund, Australian Cattle Dog, Cocker Spaniel, Chesapeake Bay Retriever, Entlebucher Sennenhund, Sloughi, Yorkshire Terrier, Tibet Mastiff, Tibet Terrier and Labrador Retriever breeds. In the following breeds the ROM1 gene was also excluded indirectly for gPRA: Miniature Poodle, Dachshund, Australian Cattle Dog, Sloughi, Collie, Tibet Terrier, Labrador Retriever and Saarloos/Wolfhound. Digenic inheritance for gPRA is practically excluded for both these genes in four breeds: Miniature Poodle, Dachshund, Labrador Retriever and Saarloos/Wolfhound.
Giuliano, E. A. and A. van der Woerdt (1999). "Feline retinal degeneration: clinical experience and new findings (1994-1997)." J Am Anim Hosp Assoc 35(6): 511-4. A retrospective case series of 26 cats with diffuse retinal degeneration is presented. The most common presenting complaints included bumping into objects, dilated pupils, and reluctance to jump. Ophthalmic examination findings were consistent with those reported in dogs with progressive retinal atrophy. Breed predilection of the Siamese cat was observed. Cats with primary retinal degeneration presented late in the clinical course of their disease, when vision loss was severe. Early symptoms such as night blindness and secondary ocular complications (i.e., cataract and retinal detachment), reported in dogs with progressive retinal degeneration, were not observed in this study. All cats showed excellent adaptive capabilities to blindness.
Sargan, D. R., P. J. Clements, et al. (1994). "Progressive retinal atrophy: a model for retinitis pigmentosa in companion animals." Gene Ther 1 Suppl 1: S89. The generalised progressive atrophies (PRA's) are a heterogeneous group of inherited retinopathies in dogs and cats. They show marked similarities to the retinitis pigmentosas (RP) in man, as well as to a number of inherited retinal degenerations of laboratory rodents. Of the various recessively inherited forms of PRA in the dog, that in the Irish setter is due to a nonsense mutation in the gene encoding cGMP-PDE-beta subunit. Mutations at this locus are also known to cause a proportion of human RP cases. We are interested in applying gene therapy to these diseases.
Millichamp, N. J. (1990). "Retinal degeneration in the dog and cat." Vet Clin North Am Small Anim Pract 20(3): 799-835. Retinal degenerations in the dog and cat are an important cause of blindness in these species. Particularly in the dog, many retinal degenerations, collectively called progressive retinal atrophy, seen in clinical practice are inherited. The clinical signs, electrophysiological findings, pathology, and underlying biochemical defects in the retina vary from breed to breed. Specific categories of inherited retinal degeneration are now recognized, and classified into early onset photoreceptor dysplasias, late-onset retinal degenerations, or retinal degenerations secondary to primary RPE dystrophy. As new inherited retinal degenerations are reported in different breeds they can generally be assigned to one these categories. Other causes of retinal degeneration include nutritional deficiencies, glaucoma, inflammation, ischemia, and toxins. Idiopathic retinal degeneration occurs in the dog with some frequency.
Van Veen, T., R. Cantera, et al. (1989). "Postnatal development of photoreceptor proteins in mutant mice and Abyssinian cats with retinal degeneration." Progress in Clinical and Biological Research 314(Inherited Environ. Induced Retinal Degener.): 275-89. The development of opsin, transducin-a, and S-antigen in photoreceptor cells of mice homozygous or heterozygous for the rd or rds genes was similar to that in control mice during the 1st postnatal wk. While the abs. amts. of these proteins were low or decreased in the postnatal period, they persisted through the entire degeneration process. The major manifestation in the mutant retinae was a loss of polarity of the photoreceptor cells, without a loss in visual protein formation. In the Abyssinian cat model of progressive retinal atrophy, the development and cellular distribution of all proteins were similar in control and affected retinae until the beginning of stage 2 of the disease. At this point, the outer segments degenerated causing a loss of photoreceptors and of IRBP glycolipoproteins in the eyes. [on SciFinder (R)]
Curtis, R., K. C. Barnett, et al. (1987). "An early-onset retinal dystrophy with dominant inheritance in the Abyssinian cat. Clinical and pathological findings." Invest Ophthalmol Vis Sci 28(1): 131-9. The clinical and pathological features of an early-onset autosomal dominant photoreceptor degeneration in the Abyssinian cat are described. Ophthalmoscopic evidence of retinal disease at 8-12 weeks of age was always preceded by marked dilatation of the pupils, impairment of the pupillary light reflex, and nystagmus. The electroretinogram was unrecordable in all but one of the affected individuals examined. Abnormal photoreceptor development was observed by both light and electron microscopy in retinas of a 22-day-old kitten; in this individual, no outer segment material was detected, and inner segments showed impaired development which was more severe towards the posterior pole. In a 40-day-old kitten, the inner segments were relatively well-formed, whereas the outer segments, though present, showed marked disorganization and degenerative change. The retinas of older individuals showed more advanced photoreceptor degeneration, with thinning of the neural retina. This early-onset retinopathy, which may be classified as a rod-cone dysplasia, is distinct from the hereditary retinal dystrophy (progressive retinal atrophy) previously described in this breed. The gene symbol Rdy has been adopted.
Narfstrom, K. and S. E. Nilsson (1986). "Progressive retinal atrophy in the Abyssinian cat. Electron microscopy." Invest Ophthalmol Vis Sci 27(11): 1569-76. Seven adult Abyssinian cats at different stages of a recessively inherited retinal degenerative disease (progressive retinal atrophy) were studied ultrastructurally. At the stage of early disease, in 2-yr-old cats, disorganized and vesiculated discs were found in less than half of the rod outer segments in the periphery, while similar changes were seen in the central retina only infrequently or in patches. Cones appeared normal in all areas of the retina at the early stage. With progression of disease, the lesions were more advanced in all areas of the retina, and involved both rods and cones, with the most severe alterations found in the midperiphery. At the advanced stage, in a 6-yr-old cat, both rods and cones were lost, the inner nuclear layer thus being separated from the pigment epithelium by Muller cell processes and a few remaining outer plexiform processes only. Remnants of photoreceptor outer and inner segments, macrophages, and what appeared to be displaced photoreceptor cell nuclei could be found occasionally in the subretinal space, however. Clumps of pigment granules were often observed in the photoreceptor layer in the non-tapetal fundus. The pigment epithelium remained morphologically intact as a single layer of uninterrupted cells throughout the disease process, as did tapetal cells and choriocapillaris. There was no difference in the severity of disease between the peripheral tapetal and non-tapetal fundus. In the inner retina, only minor alterations were observed. These changes appeared at a later time than photoreceptor degeneration, and were considered secondary to the latter.
Sarva, R. (1986). "Progressive retinal atrophy in the Abyssinian cat." Nord Vet Med 38(6): 388-93. Eight cases of hereditary progressive retinal atrophy in Abyssinian cats in Denmark are reported. Pedigree studies indicate direct lineage to affected cats of the same breed in Sweden. The disease is bilateral, progressive, and of the generalized type, and ultimately leads to blindness.
Barnett, K. C. and R. Curtis (1985). "Autosomal dominant progressive retinal atrophy in Abyssinian cats." J Hered 76(3): 168-70. Hereditary progressive retinal atrophy in Abyssinian cats in England is recorded. It is compared with another hereditary retinopathy in the same breed in Sweden and it is concluded that these are two distinct conditions, one occurring at an early age in kittens with an autosomal dominant mode of inheritance, the other occurring in young adult cats due to an autosomal recessive gene. The two diseases are bilateral, progressive, and of the generalized type, and are similar ophthalmoscopically.
Narfstrom, K. (1985). "Progressive retinal atrophy in the Abyssinian cat. Clinical characteristics." Invest Ophthalmol Vis Sci 26(2): 193-200. Ninety-four cases of a hereditary retinal degeneration in household Abyssinian cats were found in Sweden, mainly during a 3-year period. The disease was investigated by ophthalmoscopy, fluorescein angiography, electroretinography, and light microscopy. A bilateral retinopathy was usually first seen in affected cats at the age of 1.5-2 years. Fluorescein angiography did not demonstrate abnormalities of etiological significance to the disease process. A reduction mainly of a- and b-wave amplitudes in the ERG indicated a generalized photoreceptor disease. Light microscopy showed that the photoreceptor layer was primarily affected, while other retinal layers were mainly normal. The midperipheral and peripheral retina was affected more severely than the retina of the posterior pole until late stages of disease, when there was a generalized loss of photoreceptors. The clinical and laboratory findings suggest that PRA in these Abyssinian cats is a heritable photoreceptor degenerative disease with a fairly slow rate of progression.
Narfstrom, K. (1983). "Hereditary progressive retinal atrophy in the Abyssinian cat." J Hered 74(4): 273-6. Progressive retinal atrophy (PRA), a hereditary eye disease leading to blindness, was found in the Abyssinian breed of cat. Sixty-eight cases of a bilateral generalized retinopathy, at different stages of the disease process, were seen in the breed during ophthalmoscopic examinations of cats throughout Sweden during a 2-year period. Forty-five percent of cats aged 2 years or older were affected in the examined group. The earliest case was diagnosed in a 16-month-old cat. At the age of 3-4 years a bilateral retinal atrophy was usually present in affected cats. Genetic analysis indicates that PRA in the Abyssinian cat is caused by an autosomal recessive gene.
Narfstrom, L. K. and S. E. Nilsson (1983). "Progressive retinal atrophy in the Abyssinian cat: an update." Vet Rec 112(22): 525-6.
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How do you check your cats eyesight This is done by specialist, your veterinary should be able to tell you whom to contact. There is always the possibility of new mutations to surface, to monitor this for PRA one can examine cats with ophtamologic examinations. Already a very early onset PRA has been found in Abyssinians in Great Britain and there are many cases in the persian breed. Late onset type of PRA has been found in Siameses and Russians as well. In dogs there are a number of mutations known that gives PRA. To avoid new PRA disasters in any cat breed it is prudent to submit cats that breed or have had kittens at least twice for ophtamologic examinations: once before two years of age and once at age 5-7. If there are indications of PRA in the particular species and no DNA test is available examinations should be more frequent. |
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Recently it has been found that of 37 Ocicats tested with DNA test for the autosmal reessive mutationen that causes blindness in cats, 7 have been found to be carriers and 30 normal with respect to the mutation. Tested cats were from Sweden and Norway, Abyssinians in the pedigrees were in the 8 generation, which means that they were non Scandinavian abyssinans. The cats are related, so we do not know how large the problem is within the global Ocicat population. Already 2007 there was an article published were an Ocicat was found to be carrier, thus proving that the hereditary defect exists in the Ocicat breed (Menotti-Raymond, M., V. DAVID, et al. (2007). "Mutation in CEP290 Discovered for Cat Model of Human Retinal Degeneration." J. of Heredity: doi:10.1093/jhered/esm019.)
Fortunately there is a DNA test available for this autosomal recessive trait, which means that this problem is easily controlled in future litters, provided that the parents are tested and carriers are only mated to normal cats with respect to the mutation that gives PRA.
Any cat of any kind with double mutations will become blind with time. However, this do not mean that if a cat is tested and found normal it cannot become blind from other reasons. This is why it is prudent to submit a breeding cat to ophtamologic examination at least twice. Testing is done with blood or cheek swabs that can be ordered from Laboklin (Germany) or UC Davis. Results are ready within 10-30 days
At the World Small Animal Veterinary Association WSAVA congress in Dublin 2008 there was a presentation regarding the prevalence of the rdAc mutation causing blindness in cats in the Abyssinian /Somali breed. A total of 484 cheek swabs from Abyssinian and Somali cats from 14 different European countries were analyzed. Sixty one percent were found to be homozygous normal, 31% heterozygous and 4% homozygous affected for the causative mutation. Summary of the talk is below. Conferece proceedings: “Late Onset Progressive Retinal Atrophy (PRA) in the Abyssinian and Somali Cat; Evaluation of Allele Frequency in Europe for the Causative Mutation Janine Huebner1, Fachtierärztin für Virologie, MRCVS; Ines Langbein-Detsch1; Kristina Narfström2 Background A recessively inherited late on-set type of PRA was described for the first time in Abyssinian cats in Sweden 25 years ago. A high frequency of the disease was observed; it was calculated that 45% of Abyssinian cats were affected by the progressively blinding disease, 44% were carriers and 11% were normal. Recently, the causative mutation for the defect was discovered; a single nucleotide polymorphism in the CEP290 gene, allowing for a mutation detection test to be developed. The present study was performed in order to elucidate the allele frequency in Europe for the causative mutation recently discovered, now not only in Abyssinian, but also in Somali cats. Methods The detection of the mutation was performed by a real-time Taq-Man PCR assay using fluorescence labeled probes specific for either the wildtype allele or the rdAc-mutation. Cheek swabs (sterile cotton swabs, Nerbe Plus) with air dried saliva obtained by the owners or EDTA-blood samples obtained by the veterinarian from individual Abyssinian and Somali cats were sent to the lab by regular mail or by courier service. Results A total of 484 cheek swabs from Abyssinian and Somali cats from 14 different European countries were analyzed. Sixty one percent were found to be homozygous normal, 31% heterozygous and 4% homozygous affected for the causative mutation. The calculated frequency of the mutant rdAc-allele of Abyssinian and Somali cats in 2007 is 19.6%. Discussion The allele frequency 25 years ago in Europe outside of Sweden is not known. It is, however, probable that the frequency was high, since there was interaction between breeders of Abyssinian and Somali cats mainly in northern Europe and affected cats were observed at the time, also in Finland, Norway, Holland and Germany. It is thus encouraging that the number of affected cats has now become markedly reduced mainly by the use of non-affected animals (cats that are heterozygous or homozygous normal for the mutation) for breeding. The mutation detection test commercially available may allow for eradication of this specific gene defect. “ Speaker Information Janine Huebner, Fachtierärztin für Virologie, MRCVS |
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Uppdated 2009-02-28 |