RESUMEN
Objective To explore the mutation of RET gene exon 11 in sporadic medullary thyroid carcinoma and to clarify the relationship between RET mutation and sporadic medullary thyroid carcinomas. Methods Genomic DNA was extracted from 17 sporadic medullary thyroid carcinoma tissues. Exon 11 of RET gene was amplified by polymerase chain reaction, analyzed by automated DNA sequencer after purification and results were compared with normal sequence. Results RET mutation was detected in 1 of 17 cases and the mutation revealed the wrong base at the position 15165(G→A) and the missense codon at 691 (ser 691 →lys). Conclusion The low rate of RET exon 11 mutation in sporadic medullary thyroid carcinomas indicate that the key gene mutations may locate on other exons of RET gene or other genes.