Polymorphisms in exon 13 and intron 14 of the RET protooncogene: genetic modifiers of medullary thyroid carcinoma?
BACKGROUND
Single-nucleotide polymorphisms (SNPs) of the RET protooncogene (RET) could modify disease susceptibility and clinical phenotype in patients with sporadic or familial medullary thyroid carcinoma (FMTC). OBJECTIVE/DESIGN OF THE STUDY: Because frequencies of RET SNPs have not yet been evaluated in patients with elevated serum concentrations of calcitonin (hCt), a biochemical marker for medullary thyroid carcinoma (MTC), we studied RET SNPs in patients with FMTC (n = 22), patients with sporadic MTC (n = 45), and 71 subjects presenting with moderately elevated hCt concentrations (basal, >10 pg/ml; pentagastrin stimulated, > 50 < 100 pg/ml) in comparison with an age- and gender-matched control group (n = 79) with basal hCt concentrations in the normal range (<5 pg/ml).


METHODS
After DNA extraction from citrated whole blood, RET exons 10, 11, 13, 14, 15, and 16 and exon/intron boundaries were analyzed by PCR-based cycle sequencing for RET germ line mutations, exonic (G691S, L769L, S836S, S904S) and intronic (IVS13+158; NCBI rs2472737 = IVS14-24) SNPs.


RESULTS
In FMTC patients, the F791Y mutation was found to be associated (P = 0.001) with the L769L SNP. The exonic SNPs (G691S, L769L, S836S, and S904S) were not different among the four groups. The intron 14 SNP (IVS14-24), however, was more frequent in individuals with elevated hCt serum concentrations (P = 0.016) and patients with sporadic MTC (P < 0.001) when compared with the control group.


CONCLUSIONS
These data suggest that the exon 13 (L769L) and the intron 14 (IVS14-24) SNPs could act as genetic modifiers in the development of some forms of hereditary and sporadic MTC, respectively.
Baumgartner-Parzer
S M
SM
Department of Internal Medicine III, Division of Endocrinology and Metabolism, Waehringer Guertel 18-20, A-1090 Vienna, Austria. sabina.baumgartner-parzer@meduniwien.ac.at
Lang
R
R
Wagner
L
L
Heinze
G
G
Niederle
B
B
Kaserer
K
K
Waldhäusl
W
W
Vierhapper
H
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018276:Carcinoma, Medullary / Q000235:genetics*; D005091:Exons; D005260:Female; D006801:Humans; D007438:Introns; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics*; D011519:Proto-Oncogenes; D013964:Thyroid Neoplasms / Q000235:genetics*
D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human