Chakravarti A, Lasher L K, Reefer J E
Department of Human Genetics, University of Pittsburgh, Pennsylvania 15261.
Genetics. 1991 May;128(1):175-82. doi: 10.1093/genetics/128.1.175.
The genetic length of a genome, in units of Morgans or centimorgans, is a fundamental characteristic of an organism. We propose a maximum likelihood method for estimating this quantity from counts of recombinants and nonrecombinants between marker locus pairs studied from a backcross linkage experiment, assuming no interference and equal chromosome lengths. This method allows the calculation of the standard deviation of the estimate and a confidence interval containing the estimate. Computer simulations have been performed to evaluate and compare the accuracy of the maximum likelihood method and a previously suggested method-of-moments estimator. Specifically, we have investigated the effects of the number of meioses, the number of marker loci, and variation in the genetic lengths of individual chromosomes on the estimate. The effect of missing data, obtained when the results of two separate linkage studies with a fraction of marker loci in common are pooled, is also investigated. The maximum likelihood estimator, in contrast to the method-of-moments estimator, is relatively insensitive to violation of the assumptions made during analysis and is the method of choice. The various methods are compared by application to partial linkage data from Xiphophorus.
以摩根或厘摩为单位的基因组遗传长度是生物体的一个基本特征。我们提出了一种最大似然法，用于根据回交连锁实验中研究的标记位点对之间的重组体和非重组体计数来估计这个量，假设无干涉且染色体长度相等。该方法允许计算估计值的标准差以及包含该估计值的置信区间。已进行计算机模拟以评估和比较最大似然法与先前提出的矩估计法的准确性。具体而言，我们研究了减数分裂次数、标记位点数以及单个染色体遗传长度的变化对估计值的影响。还研究了将两个有部分共同标记位点的独立连锁研究结果合并时出现的缺失数据的影响。与矩估计法相比，最大似然估计法对分析过程中所作假设的违反相对不敏感，是首选方法。通过将各种方法应用于剑尾鱼属的部分连锁数据进行比较。
