Kaplan J C, Kahn A, Chelly J
INSERM U129, Institut Cochin de Génétique Moléculaire, Paris, France.
Hum Mutat. 1992;1(5):357-60. doi: 10.1002/humu.1380010502.
In 1988, by using the powerful and accurate cDNA/PCR technique, it was demonstrated that there are very low levels of dystrophin mRNA in a variety of non-muscle tissues, including cultured fibroblasts and lymphoblastoid cell lines. The phenomenon was also shown for a number of other tissue-specific genes, including beta-globin, factors VIIIc and IX, anti-Müllerian hormone, L-pyruvate kinase, retinal blue pigment, phenylalanine hydroxylase. The level of transcript in inappropriate cells is exceedingly low, perhaps one mRNA per 100-1000 cells. This low-level ubiquitous transcription of tissue-specific genes was called "illegitimate" or "ectopic" transcription, and has been proven to occur for 17 gene transcripts to date. The mechanism and biological significance of illegitimate transcription are still obscure, but, since illegitimate transcripts exhibit the same pathology as legitimate transcripts, they have been useful tool in the study of already 9 inherited diseases. This strategy will be applied widely for diseases where samples from the appropriate tissue for study is difficult to obtain, or where an mRNA is easier or more informative to study than a genomic DNA (as for large genes, or where alternative splicing is involved).
1988年，通过使用强大而精确的cDNA/PCR技术，人们证明在多种非肌肉组织中，包括培养的成纤维细胞和淋巴母细胞系，肌营养不良蛋白mRNA的水平非常低。许多其他组织特异性基因也出现了这种现象，包括β-珠蛋白、凝血因子VIIIc和IX、抗苗勒管激素、L-丙酮酸激酶、视网膜蓝色色素、苯丙氨酸羟化酶。在不适当细胞中的转录水平极低，可能每100 - 1000个细胞中有一个mRNA。这种组织特异性基因的低水平普遍转录被称为“非法”或“异位”转录，迄今为止已被证明有17种基因转录本会发生这种情况。非法转录的机制和生物学意义仍然不清楚，但是，由于非法转录本与合法转录本表现出相同的病理学特征，它们已成为研究9种遗传性疾病的有用工具。对于难以获得合适研究组织样本的疾病，或者对于研究mRNA比研究基因组DNA更容易或更具信息性的疾病（如大基因，或涉及可变剪接的情况），这种策略将得到广泛应用。
