Jones M H, Nakamura Y
Department of Biochemistry, Cancer Institute, Tokyo, Japan.
Hum Mutat. 1992;1(3):224-8. doi: 10.1002/humu.1380010309.
We found somatic mutations, detected as novel PCR bands, at three separate polymorphic CA-repeat loci. At one of these loci, analyzed in a three-generation pedigree, a new band generated from the same paternal allele was observed in four of six offspring. The other two children inherited the alternative paternal allele unchanged. Somatic mutations at two additional loci were identified upon subsequent comparison of banding patterns among 25 cancers and their corresponding normal tissues at 15 CA-repeat loci. Since somatic mutations of CA-repeats seem to be quite frequent, individuals who are mosaic for CA-repeat alleles at a particular locus probably are not unusual. Hence, the possibility of somatic mutation generating new length alleles at CA-repeat loci should be considered when one compares DNA samples, whether in forensic and paternity testing, loss of heterozygosity studies, or linkage analyses.
我们在三个不同的多态性CA重复位点发现了体细胞突变，这些突变表现为新的PCR条带。在其中一个位点，通过对一个三代家系进行分析，在六个后代中的四个中观察到来自同一父本等位基因产生的新条带。另外两个孩子则未改变地继承了另一个父本等位基因。随后，通过比较15个CA重复位点处25种癌症及其相应正常组织的条带模式，又鉴定出另外两个位点的体细胞突变。由于CA重复序列的体细胞突变似乎相当频繁，因此在特定位点具有CA重复等位基因嵌合体的个体可能并不罕见。因此，当比较DNA样本时，无论是在法医鉴定和亲子鉴定、杂合性缺失研究还是连锁分析中，都应考虑体细胞突变在CA重复位点产生新长度等位基因的可能性。
