Rance K A, Heath S C, Keightley P D
Institute of Cell, Animal and Population Biology, University of Edinburgh, Scotland, UK.
Genet Res. 1997 Oct;70(2):125-33. doi: 10.1017/s0016672397002929.
In a QTL mapping study with an F2 population of mice, we have shown that one or more sex-linked factors account for a large part of the divergence between mouse lines selected for high and low body weight. Here, we describe a study undertaken to map the putative X-linked quantitative trait loci (QTLs) by backcrossing segments of chromosome from the high line onto an inbred line derived from the low line, thereby removing possible contributions from the autosomes and linked segments of the X chromosome. Sublines containing a regional at the proximal end of the X chromosome were found to be associated with large differences in body weight, and to account for almost all the difference between the lines. A Markov chain Monte Carlo based multipoint linkage analysis incorporating the available marker and phenotypic information from the backcross pedigree was used to map the QTL to a region of about 6 cM. There was no evidence for QTLs elsewhere on the chromosome. The estimated QTL effect is approximately 20% of mean body weight in males and females at 10 weeks. From results obtained from this study and the accompanying F2 analysis, we conclude the presence of a single factor for body weight localizing to about position (+/- SE) 26.4 +/- 1.2 cM on the X chromosome, which increases body weight by approximately 18% at 10 weeks. A strategy to positionally clone the QTL is discussed.
在一项对小鼠F2群体的QTL定位研究中，我们已经表明，一个或多个性连锁因子在很大程度上导致了选择用于高体重和低体重的小鼠品系之间的差异。在此，我们描述了一项研究，通过将来自高体重品系的染色体片段回交到来自低体重品系的近交系上，来定位假定的X连锁数量性状基因座（QTL），从而消除常染色体和X染色体连锁片段可能产生的影响。发现含有X染色体近端区域的亚系与体重的巨大差异相关，并几乎解释了品系间的所有差异。基于马尔可夫链蒙特卡罗的多点连锁分析结合了回交家系的可用标记和表型信息，用于将QTL定位到大约6厘摩的区域。没有证据表明染色体其他位置存在QTL。估计的QTL效应在10周龄时约为雄性和雌性平均体重的20%。根据本研究及附带的F2分析结果，我们得出结论，存在一个体重单因子，定位在X染色体上约（±标准误）26.4±1.2厘摩的位置，在10周龄时体重增加约18%。文中还讨论了对该QTL进行位置克隆的策略。
