Watkins P C, Tanzi R E, Cheng S V, Gusella J F
J Med Genet. 1987 May;24(5):257-70. doi: 10.1136/jmg.24.5.257.
Chromosome 21 is the smallest autosome, comprising only about 1.9% of human DNA, but represents one of the most intensively studied regions of the genome. Much of the interest in chromosome 21 can be attributed to its association with Down's syndrome, a genetic disorder that afflicts one in every 700 to 1000 newborns. Although only 17 genes have been assigned to chromosome 21, a very large number of cloned DNA segments of unknown function have been isolated and regionally mapped. The majority of these segments detect restriction fragment length polymorphisms (RFLPs) and therefore represent useful genetic markers. Continued molecular genetic investigation of chromosome 21 will be central to elucidating molecular events leading to meiotic non-disjunction and consequent trisomy, the contribution of specific genes to the pathology of Down's syndrome, and the possible role of chromosome 21 in Alzheimer's disease and other as yet unmapped genetic defects.
21号染色体是最小的常染色体，仅占人类DNA的约1.9%，但却是基因组中研究最深入的区域之一。对21号染色体的诸多关注可归因于其与唐氏综合征的关联，唐氏综合征是一种影响每700至1000名新生儿中就有1名的遗传疾病。尽管只有17个基因已被定位到21号染色体上，但大量功能未知的克隆DNA片段已被分离并进行了区域定位。这些片段中的大多数可检测到限制性片段长度多态性（RFLP），因此代表了有用的遗传标记。对21号染色体持续进行分子遗传学研究对于阐明导致减数分裂不分离及随之而来的三体性的分子事件、特定基因对唐氏综合征病理学的贡献以及21号染色体在阿尔茨海默病和其他尚未定位的遗传缺陷中可能发挥的作用至关重要。
