Yao Bin, Liu Xue, Liang Hua, Dong Ting-Ting, Huang Zhi-Min, Chen Xiong, Weng Jian-Ping
Department of Endocrinology, First Affiliated Hospital of Sun Yat-Sen University, China.
Endocr J. 2009;56(1):99-104. doi: 10.1507/endocrj.k08e-066. Epub 2008 Oct 9.
Germline mutations in the RET proto-oncogene (RET gene) are well documented as the genetic causes of multiple endocrine neoplasia type 2A (MEN2A). We performed genetic analysis by direct RET gene mutation analysis in a Chinese MEN2A family and compared these results with biochemical screening tests and pathological examinations. Twenty-one exons and flanking introns of the RET gene were amplified using polymerase chain reaction (PCR). The PCR products were subjected to sequencing directly, or cloned into pGEM-T plasmids and sequenced. Restriction fragment length polymorphism (RFLP) was employed to confirm the mutation on the RET sequence. A novel heterozygous mutation of a 3-bp (GAC) deletion at codon 631 (D631del) of exon 11, resulting in the deletion of an aspartic acid at the locus, was identified in four MEN2A patients and one phenotypically normal family member. The average clinical onset-age of four MEN2A patients was 33.7 years, no cervical lymph node metastasis was found in MEN2A patients with medullary thyroid carcinoma in the family. The study indicated that the novel heterozygous deletion mutation at D631 of RET gene was co-segregated with MEN2A phenotype and promoted the development of MEN2A. This report is the first description of the D631del mutation in the family with MEN2A.
RET原癌基因（RET基因）中的种系突变是多发性内分泌肿瘤2A型（MEN2A）的遗传病因，这一点已有充分记录。我们对一个中国MEN2A家系进行了RET基因直接突变分析的基因检测，并将这些结果与生化筛查试验和病理检查结果进行了比较。使用聚合酶链反应（PCR）扩增RET基因的21个外显子及其侧翼内含子。PCR产物直接进行测序，或克隆到pGEM-T质粒中再测序。采用限制性片段长度多态性（RFLP）来确认RET序列上的突变。在4例MEN2A患者和1名表型正常的家庭成员中，发现了第11外显子631密码子处一个3碱基（GAC）缺失的新型杂合突变，导致该位点的天冬氨酸缺失。4例MEN2A患者的平均临床发病年龄为33.7岁，该家系中患有甲状腺髓样癌的MEN2A患者未发现颈部淋巴结转移。该研究表明，RET基因第631位密码子处的新型杂合缺失突变与MEN2A表型共分离，并促进了MEN2A的发生发展。本报告首次描述了MEN2A家系中的D631del突变。
