Table 2.

Role of the RET variants in sporadic medullary thyroid cancer.

RET variant	Author	Cases	Controls	P	Frequency (cases vs. controls)	Genotyping platform	Conclusion	Population
G691S/S904S (rs1799939)/(rs1800863)	Elisei (2004)	106	106	0.029	27.8; 18.8	RFLP	Higher frequency in MTC patients. Does not influence RET mRNA expression	European
	Cebrian a (2005)	120	528	0.004	27; 18	TaqMan	Associated with higher risk for development of MTC. Does not affect the splicing of RET	British
	Wohllk (2005)	50	50	NS	25; 25	sequencing	N/A	Chilean
L769L (rs1800861)	Wiench (2001)	116 b	–	0.04 b	36; 15	sequencing	Associated with the presence of MTC in younger individuals	Polish
	Sromek (2010)	217	420	0.039c	48.3; 39.5 c	Sequencing	Associated with the presence of MTC in younger individuals (in homozygosis). Could influence RET mRNA structure	Polish
	Berard (2004)	184	174	NS	22.3; 25.9	sequencing	N/A	French
	Wohllk (2005)	50	50	NS	24; 23	sequencing	N/A	Chilean
S836S (rs1800862)	Gimm (1999)	50	70	0.03	9; 3.7	RFLP	More frequent in MTC patients	German- American
	Ruiz (2001)	32	250	0.04	9.3; 3.6	RFLP	Associated with higher risk for development of MTC	Spanish
	Siqueira (2010)	81	80	0.01	10.5; 3.2	RFLP	Associated with early onset and increased risk for metastatic disease	Brazilian
	Berard (2004)	184	174	NS	6.5; 5.2	sequencing	N/A	French
	Wohllk (2005)	50	50	NS	6; 1	sequencing	N/A	Chilean
S904S (rs1800863)	Wohllk (2005)	50	50	NS	27; 28	sequencing	N/A	Chilean
	Cebrian (2005)	125	528	0.005	26.4; 15.5	TaqMan	Associated with higher risk for development of MTC	British
STOP+388pb G>A (rs3026782	Cebrian (2005)	123	522	0.005	26.4; 15.5	TaqMan	Associated with higher risk for development of MTC	British
A45A G>A (rs1800858)	Cebrian (2005)	126	525	0.04	21; 27.9	TaqMan	Suggest protective effect	British

^aStudy did not confirm the previously described association between G691S and S904S;

^bThe comparison was performed between patients aged below and above 30 years;

^cFrequency of heterozygous change L769L.N/A: no association was found.