Human telomeric DNA is complex and highly variable. Subterminal sequences are associated with cis-acting determinants of allele-specific (TTAGGG)n tract length regulation and may modulate susceptibility of (TTAGGG)n tracts to rapid deletion events. More extensive subtelomeric DNA tracts are filled with segmental duplications and segments that vary in copy number, leading to highly variable subtelomeric allele structures in the human population. RNA transcripts encoded in telomere regions include multicopy protein-encoding gene families and a variety of noncoding RNAs. One recently described family of (UUAGGG)n-containing subterminal RNAs appears to be critical for telomere integrity; these RNAs associate with telomeric chromatin and are regulated by RNA surveillance factors including human homologs of the yeast Est1p protein. An increasingly detailed and complete picture of telomeric DNA sequence organization and structural variation is essential for understanding and tracking allele-specific subterminal and subtelomeric features critical for human biology.

中文翻译：

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人类端粒的结构和生物学。

人类端粒DNA复杂且高度可变。亚末端序列与等位基因特异性（TTAGGG）n道长度调控的顺式决定簇有关，并且可能调节（TTAGGG）n道对快速缺失事件的敏感性。更广泛的亚端粒DNA片段充满了节段重复和拷贝数各异的段，从而导致人群中亚端粒等位基因结构高度可变。在端粒区域编码的RNA转录本包括多拷贝蛋白质编码基因家族和各种非编码RNA。最近描述的一个含（UUAGGG）n的亚末端RNA家族对于端粒完整性至关重要。这些RNA与端粒染色质相关，并受RNA监测因子（包括酵母Est1p蛋白的人类同源物）调控。