Polymorphisms in RET gene are associated with RET/PTC rearrangements in papillary thyroid carcinoma (PTC)
Vlasta Sykorova1, Eliska Vaclavikova1, Sarka Dvorakova1, Ales Ryska2, Daniela Kodetova3, Petr Vlcek3 & Bela Bendlova1
RET proto-oncogene is activated in the development of PTC via RET/PTC rearrangements. Single nucleotide polymorphisms (SNPs) of the gene are associated with PTC in some studies. We investigated possible association of SNPs with RET/PTC in Czech patients. We analyzed 234 patients with PTC (101 fresh frozen thyroid samples, 133 paraffin-embedded formalin-fixed samples) and 172 controls. RNA from frozen samples was reversely transcribed to cDNA. RET/PTC was detected on agarose gel. DNA from all samples was used for detection of polymorphisms in the RET gene - A432A, G691S, L769L, S836S and S904S using specific TaqMan probes. The statistic evaluation (Haploview 4.1., PHASE, Fishers exact test, odds ratio) was performed. The study was approved by the Ethical Committee. RET/PTC was detected in 26 from 101 frozen samples of PTC patients (25.5%) - 2 RET/PTC1 (2%), 2 RET/PTC3 (2%) and 22 RET/PTCX (21.5%). No significant difference of SNPs and haplotypes frequencies between patients and controls was found. However, in patients the minor allele A of A432A (G/A) was significantly under-represented in patients carring RET/PTC (19.2% versus 41.2%, P=0.006). Homozygotes with the major allele G of this polymorphism have even 4.5 times higher risk of RET/PTC (P=0.002). The minor allele G of polymorphism L769L was significantly over-represented in patients carring RET/PTC compared to patients without this alteration (36.5% versus 21.5%, P=0.049) and carriers of this allele have 3 times higher risk to develop the rearrangement (P=0.036). The distribution of haplotypes significantly differed in PTC patients related to sex (P=0.04) and presence of RET/PTC (P=0.02). The carriership of the most risk haplotypes (with both risk alleles) was significantly associated with RET/PTC (P=0.002). In conclusion, major allele G of RET gene polymorphism A432A and minor allele G of polymorphism L769L are associated with high risk of RET/PTC development.
Supported by IGA MH CR NR/9165+3.