Varona L, Gómez-Raya L, Rauw W M, Ovilo C, Clop A, Noguera J L
Area de Producció Animal, Centre UdL-IRTA, Lleida, Spain.
J Anim Breed Genet. 2005 Feb;122(1):37-48. doi: 10.1111/j.1439-0388.2004.00477.x.
A Bayesian procedure is presented for detecting quantitative trait loci (QTL) affecting longitudinal traits. The statistical model assumes a QTL affecting the prior distribution of the parameters of a given production function, under a hierarchical Bayesian scheme. Marginal posterior distributions for the effects associated with the QTL are calculated using Markov chain Monte Carlo methods. Furthermore, the Bayesian analysis allows the use of some available relevant information that can improve the detection of the QTL substantially. To illustrate the procedure, an example of QTL detection using the Von Bertalanffy growth function is presented with a F2 pig population bred from Iberian boars and Landrace sows. Animals of the F2 population were genotyped for seven markers in chromosome 2 (SSC2). Two prior distributions for the mean effect of the parameters related with birth and adult weight were compared. On the one hand, vague prior distributions were used, and, on the other, there were assumed univariate Gaussian distributions that ensure biologically meaningful adult and birth weights on the posterior growth curves. Results from the second prior distribution supported the presence of QTL, by showing that individuals with both alleles of Iberian origin had lower rates of maturation. On the contrary, when vague priors were used, the procedure was not able to detect QTL.
提出了一种用于检测影响纵向性状的数量性状基因座（QTL）的贝叶斯方法。该统计模型假设在分层贝叶斯框架下，一个QTL影响给定生产函数参数的先验分布。使用马尔可夫链蒙特卡罗方法计算与QTL相关效应的边际后验分布。此外，贝叶斯分析允许使用一些可用的相关信息，这可以显著提高QTL的检测能力。为了说明该方法，给出了一个使用冯·贝塔朗菲生长函数进行QTL检测的例子，该例子基于从伊比利亚公猪和长白母猪培育的F2猪群体。对F2群体的动物进行了2号染色体（SSC2）上7个标记的基因分型。比较了与出生体重和成年体重相关参数的均值效应的两种先验分布。一方面，使用了模糊的先验分布；另一方面，则假设了单变量高斯分布，以确保后验生长曲线上成年体重和出生体重具有生物学意义。第二种先验分布的结果支持了QTL的存在，表明具有两个伊比利亚起源等位基因的个体成熟率较低。相反，当使用模糊先验时，该方法无法检测到QTL。
