Thursday, April 17, 2008

MCPH1 & cranial volume in Chinese   posted by Razib @ 4/17/2008 01:41:00 PM

A common SNP of MCPH1 is associated with cranial volume variation in Chinese population:
Microcephaly (MCPH) genes are informative in understanding the genetics and evolution of human brain volume. MCPH1 and abnormal spindle-like MCPH associated (ASPM) are the two known MCPH causing genes that were suggested undergone recent positive selection in human populations. However, previous studies focusing only on the two tag single nucleotide polymorphisms(SNPs) of MCPH1 and ASPM failed to detect any correlation between gene polymorphisms and variations of brain volume and cognitive abilities. We conducted an association study on eight common SNPs of MCPH1 and ASPM in a Chinese population of 867 unrelated individuals. We demonstrate that a non-synonymous SNP (rs1057090, V761A in BRCA1 C-terminus (BRCT) domain) of MCPH1 other than the two known tag SNPs is significantly associated with cranial volume in Chinese males. The haplotype analysis confirmed the association of rs1057090 with cranial volume, and the homozygote males containing the derived alleles of rs1057090 have larger cranial volumes compared with those containing the ancestral alleles. No recent selection signal can be detected on this SNP, suggesting that the brain volume variation in human populations is likely neutral or under very weak selection in recent human history.

They used EHH & iHS. Also, they suggest that the derived form of rs1057090 is very ancient (the SNP has a very small window of linkage disequilibrium around it).

This is Bruce Lahn's brain on ASPM and MCPH1, Did Modern Humans Get a Brain Gene from Neandertals?, Microcephalin & ASPM and Selection "controversy".