人類第21對染色體DSCR與非DSCR基因組雙核甘酸重複序列之比較

背景　染色體不分離造成第21對染色體產生三連體現象，發生唐氏症的主要區（Down syndrome critical region, DSCR），是在人類第21對染色體約的區域大約21q22.2的位置約佔長臂總數的10%。一般以為，造成唐氏症的可能原因為發生在此區重複的基因變化所導致的。方法　利用GCG程式分析基因庫（GenBank）中第21對染色體的DNA序列以比較雙核甘酸重複序列在D區域（唐氏症主要區）及E區域（非唐氏症主要區），雙核甘酸重複序列在此染色體所出現的率及其最大的長度。結果　在出現頻率方面，雙核甘酸重複序列在兩個區域之分佈情形大致相同，以(AA)n及(TT)n之頻率最高，而以(CC)n、(CG)n及(GG)n之出現頻率最低，但是在(AA)4、(AA)5、(AA)7、(AA)8及(AA)11中，以D區域較多。在長度分佈方面，D區域的(AT)n及(CT)n之最大長度大於E區域。結論　本研究呈現出雙核甘酸重複序列在人類第21對染色體D區域及E區域之中的異同，對於瞭解唐氏症中基因組結構之分析及基因表現之研究將會有所助益。

關鍵字

第21對染色體；雙核甘酸；唐氏症；微衛星

並列摘要

Background. Non-disjunction in chromosome 21 leads to Trisomy 21. The Down syndrome critical region (DSCR, region D) , a 4 Mb region around 21q22.2, makes up about 10% of the p arm of chromosome 21. It is believed that Down syndrome is a result of multiple gene changes in this region. Methods. Using the GCG program, we analyzed sequences of chromosome 21 from samples in the GeneBank. The frequency, pattern, and length of dinucleotide repeat were compared in two regions: region D and region E (non-DSCR). Results. The patterns of the different dinucleotide repeats were similar in both regions, and the frequencies of (AA)n , and (TT)n were the highest; where as the frequencies of (CG)n, (CC)n, and (GG)n were the lowest. However, the frequencies of (AA)4, (AA)5, (AA)7, (AA)8 and (AA)11 were higher in region D than in region E. In addition, the maximum length of (AT)n and (CT)n were higher in region D than in region E. Conclusions. The knowledge of the similarities in overall frequency, pattern and maximum length as well as the differences in frequency and maximum length of certain dinucleotide repeats between these two regions give a better understanding of the genomic structure and the function of DSCR.

並列關鍵字

chromosome 21；dinucleotide repeat；Down syndrome；microsatellite

國際替代計量

人類第21對染色體DSCR與非DSCR基因組雙核甘酸重複序列之比較

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