Chiu Yen-Feng, Liang Kung-Yee
Division of Biostatistics and Bioinformatics, National Health Research Institutes, Taiwan, R.O.C.
Genet Epidemiol. 2004 Feb;26(2):108-15. doi: 10.1002/gepi.10305.
Recently, Liang et al. ([2001b] Genet. Epidemiol. 21:105-122) proposed a conditional approach to assess linkage evidence on the target region by incorporating linkage information from an unlinked (reference) region using allele shared IBD (identity-by-decent) from affected sib pairs. This is carried out by conditioning on the IBD sharing value at the estimated trait locus of the reference region. Since markers considered are typically non-fully informative, the IBD sharing at each marker needs to be estimated (or imputed). In this report, we propose an alternative approach to deal with the IBD sharing in the reference region. This new approach makes full use of the observed data without having to categorize the imputed IBD sharing as needed in Liang et al. ([2001b] Genet. Epidemiol. 21:105-122). We compare these two approaches by simulating data from a variety of two-locus models including heterogeneity, additive and multiplicative with either fully informative markers or non-fully informative markers. The performance of both approaches is quite comparable showing consistent estimates of the trait locus and key genetic parameters.
最近，梁等人（[2001b]《遗传流行病学》21:105 - 122）提出了一种条件方法，通过使用患病同胞对的等位基因共享同源性（IBD），纳入来自非连锁（参考）区域的连锁信息，来评估目标区域的连锁证据。这是通过对参考区域估计性状位点处的IBD共享值进行条件设定来实现的。由于所考虑的标记通常并非完全信息性的，因此需要估计（或推断）每个标记处的IBD共享情况。在本报告中，我们提出了一种处理参考区域中IBD共享的替代方法。这种新方法充分利用了观测数据，而无需像梁等人（[2001b]《遗传流行病学》21:105 - 122）那样根据需要对推断的IBD共享进行分类。我们通过模拟来自各种两位点模型的数据来比较这两种方法，这些模型包括异质性、加性和乘性模型，使用的标记既有完全信息性的，也有非完全信息性的。两种方法的性能相当，对性状位点和关键遗传参数的估计一致。
