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- J. Mohr, I. Puls, J. Wrase,
S. Vollstaedt-Klein, T. Leménager, C. Vollmert, M. Rapp, K. Obermayer,
A. Heinz, and M. Smolka. A model comparison of COMT effects on central
processing of affective stimuli.
.
Neuroimage, 2009.
in press.
The number of studies on imaging genetics has risen considerably
over the last few years, and haplotypes are being increasingly applied as a
model to increase the explained variance in functional brain activation.
Haplotypes, however, are not always the preferable approach. While such
highly complex models have a greater capacity for fitting data, they might
also lead to over-fitting. This study compares individual single nucleotide
polymorphisms (SNPs) with haplotypes by applying both models to effects of
catechol-O-methyltransferase (COMT), one of the most extensively studied
genes in psychiatric research and imaging genetics, on the central processing
of affective cues. To our knowledge, this is the first study to compare
haplotypes and SNPs of the COMT gene in a imaging genetics study. The model
comparison in this study is based on the Akaike Information Criterion (AIC)
and the Bayesian Information Criterion (BIC). Findings reveal the simplest
model, comprising only the well studied COMT Val158Met polymorphism, to be
the most informative one. These results do not necessarily mean that
haplotype models are in general inferior to individual SNP analysis. They do
underline, however, that techniques for model comparison such as the ones
used in this study need to be employed to establish whether the increase in
likelihood provided by a more complex haplotype-based model is large enough
to warrant the increase in model complexity.
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