Zhang Bao-Rong, Song Fei, Yin Xin-Zhen, Xia Kun, Tian Jun, Huang Jian-Zheng, Xia Jia-Hui
Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China.
Yi Chuan. 2006 Nov;28(11):1345-9. doi: 10.1360/yc-006-1345.
To investigate the relationship between the clinical features and (CAG)n trinucleotide repeats in two pedigrees of Chinese Huntington's disease (HD). Clinical and neuroimaging features, the age of disease onset and pattern of transmission of the patients were studied in the two pedigrees of HD. Genomic DNA of 42 family members was used for amplification of the (CAG)n repeats of IT15 gene by PCR. The numbers of (CAG)n were determined by electrophoresis through a 6% polyacrylamide gel and direct sequence analysis. Results showed that patients in pedigree 1 were absent of the typical triad of HD symptoms or caudate atrophy. A total of 9 (5 patients and 4 asymptomatic) out of 18 family members had 40-50 (CAG)n repeats in the IT15 gene. In pedigree 2, all the patients were characterized by a triad of symptoms, including motor disturbance, cognitive impairment and psychiatric features. Three patients and two asymptomatic relatives had more than 50 (CAG)n repeats in the IT15 gene. In conclusion, the clinical symptoms are partly determined by (CAG)n repeats in the IT15 gene. The age of onset was correlated with (CAG)n repeats over 50, and the phenomenon called "anticipation" was found to have played a role.
为研究两个中国亨廷顿舞蹈病（HD）家系的临床特征与（CAG）n三核苷酸重复序列之间的关系。对两个HD家系的临床和神经影像学特征、患者发病年龄及遗传模式进行了研究。采用聚合酶链反应（PCR）对42名家庭成员的基因组DNA进行IT15基因（CAG）n重复序列的扩增。通过6%聚丙烯酰胺凝胶电泳和直接测序分析确定（CAG）n的数目。结果显示，家系1中的患者无典型的HD三联征症状或尾状核萎缩。18名家庭成员中共有9名（5例患者和4例无症状者）IT15基因的（CAG）n重复次数为40 - 50次。在第2个家系中，所有患者均具有包括运动障碍、认知障碍和精神症状在内的三联征症状。3例患者和2名无症状亲属的IT15基因（CAG）n重复次数超过50次。结论：临床症状部分由IT15基因中的（CAG）n重复序列决定。发病年龄与超过50次的（CAG）n重复序列相关，且发现“遗传早现”现象发挥了作用。
