Comparison of the gene encoding the thyroid-stimulating hormone receptor between hyperthyroid and non-hyperthyroid domestic cats.

Abstract

The prevalence of feline hyperthyroidism (FH) is increasing, yet the etiology of FH remains to be elucidated. The purpose of this study was to compare exons 1 to 5 of the thyroid-stimulating hormone receptor (TSHR) gene and the predicted encoded amino acids between hyperthyroid and unaffected cats. Genomic DNA was isolated from whole blood of hyperthyroid and non-hyperthyroid cats. Exons 1 to 5 of the TSHR gene were amplified and sequenced. DNA and amino acid sequences were compared to identify differences between phenotypes. We identified 4 polymorphisms; 1 SNP in Exon 1 (Al-10-Val), 2 SNP in Exon 4 (silent mutations) and 1 SNP in Exon 5 (Al-139-Gly). In Exon 4, some cats had an intronic 30 base pair insertion and one hyperthyroid cat had a 2 base pair deletion upstream of the coding sequence. Finding a genetic basis for FH would have important implications for its treatment, screening and prevention.