Common variants at 6q22 and 17q21 are associated with intracranial volume.
Ikram MA., Fornage M., Smith AV., Seshadri S., Schmidt R., Debette S., Vrooman HA., Sigurdsson S., Ropele S., Taal HR., Mook-Kanamori DO., Coker LH., Longstreth WT., Niessen WJ., DeStefano AL., Beiser A., Zijdenbos AP., Struchalin M., Jack CR., Rivadeneira F., Uitterlinden AG., Knopman DS., Hartikainen A-L., Pennell CE., Thiering E., Steegers EAP., Hakonarson H., Heinrich J., Palmer LJ., Jarvelin M-R., McCarthy MI., Grant SFA., St Pourcain B., Timpson NJ., Smith GD., Sovio U., Nalls MA., Au R., Hofman A., Gudnason H., van der Lugt A., Harris TB., Meeks WM., Vernooij MW., van Buchem MA., Catellier D., Jaddoe VWV., Gudnason V., Windham BG., Wolf PA., van Duijn CM., Mosley TH., Schmidt H., Launer LJ., Breteler MMB., DeCarli C.
During aging, intracranial volume remains unchanged and represents maximally attained brain size, while various interacting biological phenomena lead to brain volume loss. Consequently, intracranial volume and brain volume in late life reflect different genetic influences. Our genome-wide association study (GWAS) in 8,175 community-dwelling elderly persons did not reveal any associations at genome-wide significance (P < 5 × 10(-8)) for brain volume. In contrast, intracranial volume was significantly associated with two loci: rs4273712 (P = 3.4 × 10(-11)), a known height-associated locus on chromosome 6q22, and rs9915547 (P = 1.5 × 10(-12)), localized to the inversion on chromosome 17q21. We replicated the associations of these loci with intracranial volume in a separate sample of 1,752 elderly persons (P = 1.1 × 10(-3) for 6q22 and 1.2 × 10(-3) for 17q21). Furthermore, we also found suggestive associations of the 17q21 locus with head circumference in 10,768 children (mean age of 14.5 months). Our data identify two loci associated with head size, with the inversion at 17q21 also likely to be involved in attaining maximal brain size.