Thyroid papillary carcinoma: preliminary evidence for a germ-line single nucleotide polymorphism in the Fas gene

The expression of Fas in thyroid tumours and Graves’
disease was analysed by mRNA transcript expression. As
compared with unaffected thyroid tissue, Fas expression
was enhanced in Graves’ disease, adenomas, and papillary
and follicular carcinomas. This pattern was also reflected in
immunohistochemical studies. The PCR single-strand
conformational polymorphism (SSCP) method and DNA
sequencing were used to analyse Fas exons 1–9. The study
was carried out on five different histotypes of thyroid
tumours (n=93) and tissue from Graves’ disease patients.
As compared with a group of healthy blood donors
(n=64), a significant association (P=0·006) emerged between
papillary thyroid carcinoma and a silent single
nucleotide polymorphism (SNP, 988CT) in exon 7 of
the Fas gene. Other forms of thyroid pathology were not
associated with the above polymorphism. Patients with
neoplasia showed the same SNP in tumour tissue, in the
unaffected contralateral thyroid lobe, and in peripheral
blood cells. Thus, the 988CT polymorphism appeared
to be of germ-line origin.