汉族人群caspase10基因中存在一个新的微卫星位点

目的检测汉族人群caspase10基因（CASP10）编码区外显子及剪接区域的多态性位点，研究CASP10基因与多基因复杂疾病的关联性。方法采用聚合酶链反应（polymerase chain reaction，PCR）、变性高效液相色谱技术（denaturing high-performance liquid chromatographv，DHPLC）、直接测序及克隆测序技术检测CASP10基因第9外显子及其部分侧翼序列。结果CASP10基因第9外显子在本人群70例血样本中未检测列存在于其他人群中已知的单核苷酸多态（single nucleotide polymorphism，SNP），但初步发现在第8内含子中靠近第9外显子处存在连续重复的单核苷酸T，且T的数目在不同的个体中存在差异。测序分析显示该处为一单核苷酸重复序列，提示该位点为一单核苷酸重复微卫星位点。经比较现存的基因组数据库，先前未有类似报道。进一步采用高保真酶扩增及测序都证实同样结果。用DHPLC法检测了70例浙江汉族人群血样本，结果均呈杂合状态，暂命名为IVS8-13（T）n。结论我们的结果提示汉族人群中该位点为一杂合度较高的单核苷酸重复的微卫星位点。这一结果与NCBI的dbSNP数据库中公布的该位点为一缺失型的SNP不同，提示这一位点的遗传差异可能与种族相关。汉族人群CASP10基因中存在的这个微卫星的意义还有待于深入研究。

A novel microsatellite within intron 8 in caspase10 gene in Chinese of Han nationality

Objective To investigate polymorphisms in the coding exons and their splicing areas of caspase10 gene ( CASP10) in Chinese of Han nationality. Methods Polymerase chain reaction (PCR), denaturing high-performance liquid chromatography (DHPLC), direct sequencing and clonal sequencing were used to analyze the exon 9 and its flanking sequences. Results In 70 blood samples of Chinese subjects researched the known single nucleotide polymorphisms (SNPs) in the exon 9 of CASP10 gene published in dbSNP of NCBI were not identified. We found a short sequence with more than ten continuous and repeated T nucleotides within the intron 8 near the exon 9 and the length of repeated sequence nucleotides T was different in samples. Clonal sequencing analysis indicated that it was a microsatellite of single nucleotide-repeated sequence. The recurrence and specificity of same result was further confirmed by PCR with high fidelity polymerase and sequencing. Furthermore all of 70 blood samples detected by DHPLC showed heterozygous profiles. We named it as IVS8-13(T)n temperately. Conclusion Our research suggested that the site be a microsatellite of single nucleotide-repeated sequence. Meanwhile, our data further showed that it was quite different from that by querying SNP database of non-Chinese population in NCBI, in the same region a SNP of type of insertion deletion existed. It could be inferred that the difference between the populations might be associated with the genetic characteristics of ethnics. The significance of the microsatellite in CASP10 gene in Chinese of Han nationality remains to be elucidated.