Absence of FMR-1 gene expression can be detected with RNA extracted from dried blood specimens
✍ Scribed by Jih-Tung Pai; Shih-Feng Tsai; Chen-Jee Horng; Pao-Chin Chiu; Ming-Yuan Cheng; Kwang-Jen Hsiao; Kuang-Dong Wuu
- Publisher
- Springer
- Year
- 1994
- Tongue
- English
- Weight
- 859 KB
- Volume
- 93
- Category
- Article
- ISSN
- 0340-6717
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✦ Synopsis
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-l-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.