Millington-Ward A M, Pearson P L
Department of Human Genetics, University of Leiden, The Netherlands.
Hum Genet. 1988 Dec;80(4):362-70. doi: 10.1007/BF00273652.
Restriction fragment length polymorphic probes are being used more frequently in the molecular analysis of Down's syndrome and in the origin of nondisjunction in the syndrome. The type of information gained from RFLPs overlaps but differs from the information from cytogenetic heteromorphisms. From the allele frequencies of commonly available probes we have derived the expected frequencies of all matings in the population. Each mating has been defined and partitioned to show the genotypes and phenotypes expected, with numerical values based on studies with heteromorphisms. From this we show how the various phenotypes can be used to calculate the origin of nondisjunctions and their expected frequencies. Further, an alternative method is outlined for mapping the distance between a probe and its centromere based on the distortion, caused by crossing-over, of the expected 1st to 2nd division nondisjunction ratio. Finally, we discuss prospects for various uses of probes in the analysis of Down's syndrome.
限制性片段长度多态性探针在唐氏综合征的分子分析以及该综合征中不分离的起源研究中使用得越来越频繁。从限制性片段长度多态性（RFLP）获得的信息类型与细胞遗传学异态性的信息有重叠但也有所不同。根据常用探针的等位基因频率，我们推导出了人群中所有交配的预期频率。每种交配都已被定义和划分，以显示预期的基因型和表型，并根据异态性研究给出了数值。由此我们展示了如何利用各种表型来计算不分离的起源及其预期频率。此外，还概述了一种基于预期的第一次到第二次分裂不分离比率因交叉而产生的畸变来绘制探针与其着丝粒之间距离的替代方法。最后，我们讨论了探针在唐氏综合征分析中的各种应用前景。
