自主性功能性甲状腺腺瘤TSH受体基因突变研究

Study on the TSH receptor gene mutations of autonomously functioning thyroid adenoma

目的 研究TSH受体 (TSHR)基因突变在自主性功能性甲状腺腺瘤 (AFTA)发病中的作用。方法 以 14例AFTA作为研究对象 ,另 4例为毒性多结节性甲状腺肿、7例扫描呈“冷结节”的甲状腺腺瘤及AFTA周围正常甲状腺组织作为对照 ,酚 氯仿 异戊醇法提取基因组DNA ,对目的基因片段进行聚合酶链反应—单链构象多态性 (PCR SSCP)分析及DNA序列分析。结果 在 14例自主性功能性甲状腺瘤标本中 ,SSCP检测出 6例条带变异的个体 (4 3 % ) ,对其中 3例进行DNA序列测定 ,发现 1例为 6 2 0位密码子的点突变 ,苏氨酸被脯氨酸置换 (T6 2 0P ,ACC→CCC)。 2例为单碱基插入突变 ,在 1972与 1973位核苷酸之间插入了一个腺嘌呤核苷酸 (A) ,使得密码子 6 2 4位以后的氨基酸发生了移码突变。在对照组未发现TSHR基因突变。结论 TSHR基因突变可能在自主性功能性甲状腺腺瘤的发病中起重要作用。

Objective To obtain more information concerning the thyrotropin receptor (TSHR) gene mutations in the pathogenesis of autonomously functioning thyroid adenomas (AFTAs). Methods 14 diagnosed AFTAs were analyzed, with 4 toxic multinodular goiters, 7 thyroid adenomas (cold nodule on scintiscan) and normal thyroid specimens adjacent to the tumours as controls. The genomic DNA was extracted with phenol chlormethyl isoamyl alcohol extraction and ethanol precipitation. The 155 base pairs DNA fragments which encompasses the third cytoplasmic loop and the sixth transmembrane segments in the TSHR exon 10 were amplified by PCR and analyzed by the single strand conformation polymorphism (SSCP). Direct sequencing of the PCR products was performed with ABI Prism Dye Terminator Cycle Sequencing Core Kit. Results In SSCP analysis, 6 autonomously functioning adenomas of 14 patients displayed migration abnormally (43%). In sequence analysis of 3 abnormal migrated samples, one substitution at nucleotide 1957 (A to C), and two same insertion mutations of one adenosine nucleotide (A) insertion between nucleotide 1972 and 1973 were identified. No mutations were found in controls. Conclusion Both one point substitution mutation and one base insertion mutation of the TSHR gene may be responsible for the pathogenesis of the autonomously functioning thyroid adenomas.