title: A twin study of genetic contributions to hippocampal morphology in schizophrenia.
abstract: Our goal was to establish whether altered hippocampal morphology represents a trait marker for genetic vulnerability in schizophrenia. We outlined the hippocampi on high-resolution MR images obtained from matched samples of control and discordant monozygotic and dizygotic co-twins (N = 40 pairs). Hippocampal measures were used in statistical tests specifically designed to identify disease-associated genetic and nongenetic influences on morphology. 3D surface average maps of the hippocampus were additionally compared in biological risk groups. Smaller hippocampal volumes were confirmed in schizophrenia. Dizygotic affected co-twins showed smaller left hippocampi compared to their healthy siblings. Disease-associated effects were not present between monozygotic discordant co-twins. Monozygotic, but not dizygotic, unaffected co-twins exhibited smaller left hippocampi compared to control twins, supporting genetic influences. Surface areas and posterior volumes similarly revealed schizophrenia and genetic liability effects. Results suggest that hippocampal volume reduction may be a trait marker for identifying individuals possessing a genetic predisposition for schizophrenia.
authors.affiliation: Laboratory of Neuro-Imaging, Brain Mapping Center, Department of Neurology, UCLA Brain Mapping Center, UCLA School of Medicine, Los Angeles, California 90095, USA.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Narr
authors.forename: Theo G M
authors.initials: TG
authors.lastname: van Erp
authors.forename: Tyrone D
authors.initials: TD
authors.lastname: Cannon
authors.forename: Roger P
authors.initials: RP
authors.lastname: Woods
authors.forename: Paul M
authors.initials: PM
authors.lastname: Thompson
authors.forename: Seonah
authors.initials: S
authors.lastname: Jang
authors.forename: Rebecca
authors.initials: R
authors.lastname: Blanton
authors.forename: Veli-Pekka
authors.initials: VP
authors.lastname: Poutanen
authors.forename: Matti
authors.initials: M
authors.lastname: Huttunen
authors.forename: Jouko
authors.initials: J
authors.lastname: Lönnqvist
authors.forename: Carl-Gustav
authors.initials: CG
authors.lastname: Standerksjöld-Nordenstam
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: John C
authors.initials: JC
authors.lastname: Mazziotta
authors.forename: Arthur W
authors.initials: AW
authors.lastname: Toga
mesh_terms: D000328:Adult; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000235:genetics* / Q000473:pathology*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic