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脆性X综合征基因(FMR—1)是儿童智力低下的最常见病因,其特征是在编码精氨酸残基的第一个外显子内有一长的CGG3核苷酸重复(突变)。本病的男性患者CGG重复明显增多,与其相应的DNA片段显著增大,并可发现有多条粗大的带或模糊区带。无脆性X综合征表现的男性携带者增大较轻,但女性携带者增大的带和模糊区带较男性携带者明显。这些所见现在均可用PCR法进行检测,也可用Sourthern法分析FMR—1内的长度突变。FMR—1可用于检测携带者、产前诊断和进行群体的筛选。
Fragile X syndrome gene (FMR-1) is the most common cause of mental retardation in children and is characterized by a long CGG3 nucleotide repeat (mutation) within the first exon encoding arginine residues. CGG duplication of patients with this disease significantly increased, with its corresponding DNA fragment was significantly increased, and found that there are a number of thick band or fuzzy zone. Male carriers with no manifestation of Fragile X syndrome showed a lighter increase, but increased bands and hazy zones were more pronounced in women than in men. These findings can now be detected by PCR method, the length of the FMR-1 mutations can also be analyzed by the method of Sourthern. FMR-1 can be used to detect carriers, prenatal diagnosis, and population screening.