Pai J T, Tsai S F, Horng C J, Chiu P C, Cheng M Y, Hsiao K J, Wuu K D
Institute of Genetics, National Yang-Ming Medical College, Taipei, Taiwan, ROC.
Hum Genet. 1994 May;93(5):488-93. doi: 10.1007/BF00202810.
Fragile X syndrome is a genetic disorder caused by abnormal function of the FMR-1 gene. The majority of fragile X syndrome patients carry an expansion of the CGG tri-nucleotide repeat in the FMR-1 gene, whereas others have a deletion or a point mutation in the FMR-1 structural gene. In this report, we analyzed a typical family with three male patients. RNA from Epstein-Barr virus transformed lymphoblastoid cells was used for RNase protection assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Five normal individuals and one asymptomatic heterozygote from this family expressed detectable FMR-1 transcripts, whereas three fragile X patients showed no sign of expression with either assay. To extend the application of this PCR-based assay to laboratory diagnosis of fragile X syndrome, we confirmed that dried blood samples collected on screening filter papers for newborns are an adequate source of RNA for RT-PCR. Moreover, fragile X patients from the study family and another family were reliably identified by the absence of the FMR-1-specific PCR product from the dried blood specimens. Our studies indicate that this simple assay can be used to diagnose the fragile X syndrome for the majority of male patients.
脆性X综合征是一种由FMR-1基因功能异常引起的遗传性疾病。大多数脆性X综合征患者在FMR-1基因中携带CGG三核苷酸重复序列的扩增，而其他患者在FMR-1结构基因中存在缺失或点突变。在本报告中，我们分析了一个有三名男性患者的典型家庭。来自爱泼斯坦-巴尔病毒转化的淋巴母细胞样细胞的RNA用于核糖核酸酶保护试验和逆转录-聚合酶链反应（RT-PCR）分析。该家庭的五名正常个体和一名无症状杂合子表达了可检测到的FMR-1转录本，而三名脆性X患者在两种检测方法中均未显示表达迹象。为了将这种基于PCR的检测方法扩展应用于脆性X综合征的实验室诊断，我们证实，在新生儿筛查滤纸上采集的干血样本是用于RT-PCR的充足RNA来源。此外，通过干血标本中缺乏FMR-1特异性PCR产物，可靠地鉴定了来自研究家庭和另一个家庭的脆性X患者。我们的研究表明，这种简单的检测方法可用于诊断大多数男性患者的脆性X综合征。
