Loss of heterozygosity in follicular and papillary thyroid carcinomas

In this study we aimed at investigating the incidence and the role of 3p deletions, particularly at the 3p25 approximately pter region, in follicle cell-derived thyroid neoplasms, by using loss of heterozygosity (LOH) analysis. We analyzed 12 follicular adenomas (FA), 13 follicular thyroid carcinomas (FTC), and 15 papillary thyroid carcinomas (PTC) with 11 microsatellite markers for chromosome 3. One additional marker on 3q25.2 was also investigated for assessment of deletion extent on 3q. Microsatellite instability was detected at one locus in 1 of 15 PTC (7%) and at four loci in 1 of 13 FTC (8%). Loss of heterozygosity was found in 8 of 12 cases of FTC (67%), in 6 of 15 cases of PTC (40%), and in 2 of 12 FA (17%). We identified three minimal common deleted regions (CDR) involving significant sites of LOH: two in FTC (a new terminal region, of approximately 8 cM distal to D3S1620 at 3p25.3 approximately pter and the D3S1573-D3S1595 region at 3p21.2 approximately p12) and one in PTC (D3S1304-D3S1263 region at 3p25.3 approximately p24.2). The newly identified 3p25.3 approximately pter CDR seems to be specific for FTC. Our results suggest the existence of at least three distinct regions on 3p that might harbor tumor suppressor genes involved in the carcinogenesis processes of FTC and PTC.