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M A Spence

Publications and source records attributed to M A Spence.

149 records · Page 9Linked to original sources
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Estimating recombination fraction separately for males and females: a counterintuitive result.

In the course of performing a linkage analysis on rats bred from inbred doubly heterozygous parents, we observed the following counterintuitive finding: the lod scores more strongly supported the hypothesis that all the recombinations occurred in one sex (without specifying which sex), rather than that some recombinations occurred in each sex. In this brief paper we explain how this apparent anomaly can arise. We point out that very different values of the recombination fraction vector theta = (theta Male, theta Female) can give rise to likelihoods that do not differ by much. We suggest that caution be exercised when investigators interpret results of linkage analyses in which estimates of theta Male and theta Female differ widely.

Animals↗
PubMedDate not supplied

Methodological issues in linkage analyses for psychiatric disorders: secular trends, assortative mating, bilineal pedigrees. Report of the MacArthur Foundation Network I Task Force on Methodological Issues.

A Task Force was assembled to address three data problems in genetic linkage analyses: (1) a secular trend, e.g. cohort effect; (2) positive assortative mating, and (3) bilineal pedigrees. All are cited as reasons for failure to replicate genetic linkage reports. However, we knew of no work demonstrating that these factors could invalidate or bias linkage analyses, nor that they were complications (e.g., variable age of onset). The Task Force concluded that these factors can reduce the power of linkage analyses and result in bias in the estimate of the recombination frequency due to the fact that they represent 'noise' in the system. There was little evidence that the three factors would invalidate a linkage analysis or be directly responsible for negating a linkage finding.

Cohort Effect↗