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Crossover interference and sex-specific genetic maps shape identical by descent sharing in close relatives.
PLOS Genetics ( IF 4.0 ) Pub Date : 2019-12-20 , DOI: 10.1371/journal.pgen.1007979
Madison Caballero 1 , Daniel N Seidman 2 , Ying Qiao 2 , Jens Sannerud 2 , Thomas D Dyer 3 , Donna M Lehman 4 , Joanne E Curran 3 , Ravindranath Duggirala 3 , John Blangero 3 , Shai Carmi 5 , Amy L Williams 2
Affiliation  

Simulations of close relatives and identical by descent (IBD) segments are common in genetic studies, yet most past efforts have utilized sex averaged genetic maps and ignored crossover interference, thus omitting features known to affect the breakpoints of IBD segments. We developed Ped-sim, a method for simulating relatives that can utilize either sex-specific or sex averaged genetic maps and also either a model of crossover interference or the traditional Poisson model for inter-crossover distances. To characterize the impact of previously ignored mechanisms, we simulated data for all four combinations of these factors. We found that modeling crossover interference decreases the standard deviation of pairwise IBD proportions by 10.4% on average in full siblings through second cousins. By contrast, sex-specific maps increase this standard deviation by 4.2% on average, and also impact the number of segments relatives share. Most notably, using sex-specific maps, the number of segments half-siblings share is bimodal; and when combined with interference modeling, the probability that sixth cousins have non-zero IBD sharing ranges from 9.0 to 13.1%, depending on the sexes of the individuals through which they are related. We present new analytical results for the distributions of IBD segments under these models and show they match results from simulations. Finally, we compared IBD sharing rates between simulated and real relatives and find that the combination of sex-specific maps and interference modeling most accurately captures IBD rates in real data. Ped-sim is open source and available from https://github.com/williamslab/ped-sim.

中文翻译:


交叉干扰和性别特异性遗传图谱通过近亲共享血统而形状相同。



近亲和同源 (IBD) 片段的模拟在遗传学研究中很常见,但过去的大多数努力都利用了性别平均遗传图谱并忽略了交叉干扰,从而忽略了已知影响 IBD 片段断点的特征。我们开发了 Ped-sim,这是一种模拟亲属的方法,可以利用特定性别或性别平均遗传图谱,也可以使用交叉干扰模型或传统的交叉距离泊松模型。为了描述以前被忽视的机制的影响,我们模拟了这些因素的所有四种组合的数据。我们发现,对交叉干扰进行建模后,在堂兄弟姐妹中,成对 IBD 比例的标准偏差平均降低了 10.4%。相比之下,特定性别的地图平均使标准差增加 4.2%,并且还会影响亲属共享的细分数量。最值得注意的是,使用特定性别的地图,同父异母的兄弟姐妹共享的片段数量是双峰的;与干扰模型相结合,第六代堂兄弟姐妹拥有非零 IBD 共享的概率范围为 9.0% 到 13.1%,具体取决于与他们相关的个体的性别。我们提出了这些模型下 IBD 细分分布的新分析结果,并表明它们与模拟结果相匹配。最后,我们比较了模拟亲属和真实亲属之间的 IBD 共享率,发现性别特异性地图和干扰模型的结合最准确地捕获了真实数据中的 IBD 率。 Ped-sim 是开源的,可从 https://github.com/williamslab/ped-sim 获取。
更新日期:2019-12-21
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