Shs. Pearce et al., MUTATIONAL ANALYSIS OF THE THYROTROPIN RECEPTOR GENE IN SPORADIC AND FAMILIAL FELINE THYROTOXICOSIS, Thyroid, 7(6), 1997, pp. 923-927
The characterization of a spontaneous animal model equivalent to a hum
an form of thyrotoxicosis would provide a useful resource for the inve
stigation of the human disorder. Feline thyrotoxicosis is the only com
mon form of hyperthyroidism found in domestic or laboratory animals, b
ut its etiopathogenesis remains poorly defined. We have used the polym
erase chain reaction (PCR) to amplify codons 480-640 of the previously
uncharacterized feline thyrotropin receptor (TSHR) gene, and have det
ermined the DNA sequence in this transmembrane domain region. We have
analyzed single stranded conformational polymorphisms in thyroid DNA f
rom 11 sporadic cases of feline thyrotoxicosis and leukocyte DNA from
two cases of familial feline thyrotoxicosis. We have also determined t
he DNA sequence of this region of the TSHR in five of the cases of spo
radic feline thyrotoxicosis and the two familial thyrotoxic cats. The
normal feline TSHR sequence between codons 480-640 is highly homologou
s to that of other mammalian TSHRs, with 95%, 92%, and 90% amino acid
identity between the feline receptor and canine, human, and bovine TSH
Rs, respectively. Thyroid gland DNA from 11 cats with sporadic thyroto
xicosis did not have mutations in this region of the TSHR gene. Leukoc
yte DNA from two littermates with familial feline thyrotoxicosis did n
ot harbor mutations of this region of the TSHR gene. These studies sug
gest that TSHR gene mutations are not a common cause of feline thyroto
xicosis.