ISOLATION OF CANINE RETINAL ARRESTIN CDNA AND EXCLUSION OF 3 CANDIDATE GENES FOR SWEDISH-BRIARD RETINAL DYSTROPHY

Purpose. Mutations of genes encoding various retina-specific proteins are known to cause a wide spectrum of inherited retinal dystrophies in different species. In the canine, several types of genetic retinal dy strophies have been described affecting primarily the photoreceptors a nd/or the retinal pigment epithelium. We are performing a systematic a nalysis of canine candidate genes for such diseases to identify the on e mutated in the retinal dystrophy in Swedish Briard dogs. Methods. We isolated and characterised the full length cDNA of canine retinal arr estin by the method of rapid amplification of cDNA ends (RACE). Result s. The full length cDNA isolated by us is 1,575 base pairs (bp) long a nd contains a 1,218 bp-long open reading frame. Conclusions. The homol ogy of the canine arrestin protein is highest with the human analogue (88.9%) and lowest with mouse arrestin (85.3%), The most obvious seque nce differences among the different arrestins are in the extreme carbo xyl terminus. PCR-SSCP (single strand conformation polymorphism) analy sis and direct sequencing of retinal cDNA didn't provide any evidence that mutations in the canine arrestin gene are responsible for the ret inal dystrophy seen in the Swedish strain of Briard dogs, Similar data were obtained for the genes encoding rhodopsin and the beta-subunit o f photoreceptor-specific phosphodiesterase by segregation analysis.