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Abstract
Choosing the appropriate neuroimaging phenotype is critical to successfully identify
genes that influence brain structure or function. While neuroimaging methods provide
numerous potential phenotypes, their role for imaging genetics studies is unclear.
Here we examine the relationship between brain volume, grey matter volume, cortical
thickness and surface area, from a genetic standpoint. Four hundred and eighty-six
individuals from randomly ascertained extended pedigrees with high-quality T1-weighted
neuroanatomic MRI images participated in the study. Surface-based and voxel-based
representations of brain structure were derived, using automated methods, and these
measurements were analysed using a variance-components method to identify the heritability
of these traits and their genetic correlations. All neuroanatomic traits were significantly
influenced by genetic factors. Cortical thickness and surface area measurements were
found to be genetically and phenotypically independent. While both thickness and area
influenced volume measurements of cortical grey matter, volume was more closely related
to surface area than cortical thickness. This trend was observed for both the volume-based
and surface-based techniques. The results suggest that surface area and cortical thickness
measurements should be considered separately and preferred over gray matter volumes
for imaging genetic studies.
Copyright 2009 Elsevier Inc. All rights reserved.