[中国东北地区汉族人群SCA1和SCA3/MJD基因CAG重复序列的分析与应用]

[Analysis and application of SCA1 and SCA3/MJD gene CAG repeats in Han population in Northeastern China].

作者信息

Jiang Miao, Jin Chun-lian, Lin Chang-kun, Qiu Guang-rong, Liu Zong-lan, Wang Chao-xiang, Sun Kai-lai

机构信息

Department of Medical Genetics, China Medical University, Shenyang, Liaoning, PR China.

出版信息

Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2004 Feb;21(1):83-5.

PMID:14767919

Abstract

OBJECTIVE

To investigate the normal range of (CAG)n in spinocerebellar ataxia type 1 (SCA1) gene and spinocerebellar ataxia type 3 (SCA3/MJD) gene in 110 normal subjects of Han population in Northeastern China, to assess the genotypes for clinically diagnosed spinocerebellar ataxia(SCA) individuals including 25 patients from 8 families and 6 sporadic patients, and to make presymptomatic and prenatal diagnosis.

METHODS

DNA fragments from the normal subjects and the patients were detected by fluorescence-PCR. Homozygosities were selected for DNA sequencing.

RESULTS

The normal ranges of (CAG)n of SCA1 and SCA3/MJD were 20-39 and 14-38 repeats respectively, SCA1 was found mostly to be 26 and 27 repeats, allele frequency 34.09% and 20.91%; heterozygosity was 84.55%, SCA3/MJD was found mostly to be 14 repeats, allele frequency 39.55%, heterozygosity was 78.18%.(CAG)(68) of SCA3/MJD gene of one affected individual had been found in a family but no CAG mutative expansion in related members was observed.

CONCLUSION

The normal ranges of CAG repeats vary with areas and races. SCAs genotyping is the first choice in presymptomatic and prenatal diagnosis.

摘要

目的

研究中国东北地区110名汉族正常人群脊髓小脑共济失调1型（SCA1）基因和脊髓小脑共济失调3型（SCA3/MJD）基因中（CAG）n的正常范围，对8个家系的25例患者及6例散发患者等临床诊断为脊髓小脑共济失调（SCA）的个体进行基因分型，并进行症状前诊断和产前诊断。

方法

采用荧光定量PCR技术检测正常人和患者的DNA片段，选择纯合子进行DNA测序。

结果

SCA1和SCA3/MJD基因（CAG）n的正常范围分别为20～39次重复和14～38次重复，SCA1基因主要为26次和27次重复，等位基因频率分别为34.09%和20.91%，杂合度为84.55%；SCA3/MJD基因主要为14次重复，等位基因频率为39.55%，杂合度为78.18%。在一个家系中发现1例患者SCA3/MJD基因（CAG）68，但相关成员未观察到CAG突变性扩展。