Williamson R, Davies K E, Donald J, Gilliam C, Wallis S, Humphries S
Biochem Soc Symp. 1984;49:183-8.
Each human cell contains enough DNA to code for several million proteins. As a result of the technical advances which are broadly described as 'genetic engineering', each of these sequences can be isolated and purified in large amounts, free from those surrounding it in the genome. The sequences are not identical from person to person, nor even for each of a pair of chromosomes for a single person, but contain many variations. These include single base changes in both coding and non-coding regions, deletions, insertions and rearrangements. Using these changes as markers, the molecular geneticist can compare the structure and expression of normal and mutated human gene sequences and follow their inheritance in families.
每个人类细胞都含有足够的DNA，能够编码数百万种蛋白质。由于被广泛称为“基因工程”的技术进步，这些序列中的每一个都可以被大量分离和纯化，且不受基因组中其周围序列的影响。这些序列在人与人之间并不相同，甚至同一个人的一对染色体中的每条染色体上的序列也不相同，而是包含许多变异。这些变异包括编码区和非编码区的单碱基变化、缺失、插入和重排。利用这些变化作为标记，分子遗传学家可以比较正常和突变的人类基因序列的结构和表达，并追踪它们在家族中的遗传情况。
