The Thai Journal of Veterinary Medicine


Canine genetic disorders inherited through genes or chromosomes. Mutations can also occur spontaneouslyor influenced by environmental factors. Such disorders can be transmitted to offspring. However, the disease may notbe developed owing to other influenced factors. Dominant and recessive genetic mechanisms also affect the traitoutcome. This article discussed the abnormalities of genes affected by the disease and/ or genetic disorders in Collies,Shetland sheepdogs and Border collies, sharing the Collie lineage. Most of these disorders are caused by autosomalrecessive genes. Hence, paired recessive alleles are required in order to express its phenotype. Although dogs areasymptomatic carriers, they can pass down defective genes to offspring. The first gene to be described was multidrugresistance gene 1 (MDR1), which expresses P-glycoprotein, functioning to eliminate a number of drugs from thebrain. The other genes included nonhomologous end joining (NHEJ1), retinal degeneration 3 (RD3) and ceroidlipofuscinosis neuronal 5 (CLN5) genes which are associated with Collie eye anomaly, rod-cone dysplasia and type 2disease neuronal ceroid lipofuscinosis, respectively. Knowledge of genes associated with genetic diseases leads to thedevelopment of the DNA tests for early diagnosis and breed selection. This will help reduce the incidence of suchdisorders.

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