Stallings R L
Department of Human Genetics, University of Pittsburgh, Pennsylvania 15261.
Genomics. 1994 May 1;21(1):116-21. doi: 10.1006/geno.1994.1232.
The distribution of all trinucleotide microsatellite sequences in the GenBank database was surveyed to provide insight into human genetic disease syndromes that result from expansion of microsatellites. The microsatellite motif (CAG)n is one of the most abundant microsatellite motifs in human GenBank DNA sequences and is the most abundant microsatellites found in exons. This fact may explain why (CAG)n repeats are thus far the predominant microsatellites expanded in human genetic diseases. Surprisingly, (CAG)n microsatellites are excluded from intronic regions in a strand-specific fashion, possibly because of similarity to the 3' consensus splice site, CAGG. A comparison of the positions of microsatellites in human vs rodent homologous sequences indicates that some arrays are not extensively conserved for long periods of time, even when they form parts of protein coding sequences. The general lack of conservation of trinucleotide repeat loci in diverse mammals indicates that animal models for some human microsatellite expansion syndromes may be difficult to find.
对GenBank数据库中所有三核苷酸微卫星序列的分布进行了调查，以深入了解由微卫星扩增导致的人类遗传疾病综合征。微卫星基序（CAG）n是人类GenBank DNA序列中最丰富的微卫星基序之一，也是在外显子中发现的最丰富的微卫星。这一事实可能解释了为什么（CAG）n重复序列是迄今为止在人类遗传疾病中扩增的主要微卫星。令人惊讶的是，（CAG）n微卫星以链特异性方式被排除在内含子区域，可能是因为与3'共有剪接位点CAGG相似。对人类与啮齿动物同源序列中微卫星位置的比较表明，即使某些阵列构成蛋白质编码序列的一部分，它们在很长一段时间内也没有广泛保守。不同哺乳动物中三核苷酸重复位点普遍缺乏保守性，这表明可能很难找到某些人类微卫星扩增综合征的动物模型。
