HLA-A and CTGB33 polymorphisms and variation in IQ scores

This study attempted to replicate findings of Plomin et al. (Plomin et al. (1991). DNA markers associated with high vs low IQ: The IQ quantitative tra it loci (QTL) project, Behav, Genet., 24, 107-118) in which significant dif ferences in allelic frequency at a locus in the HLA class I region and the triplet repeat, CTGB33 were found between low and high IQ subjects. The two IQ groups for our study were taken from a sample of elderly people whose I Q was assessed using a measure of intelligence that is highly resistant to the effects of ageing and dementia. The high IQ group had an average IQ of 125 while the lower group's;average IQ was 95. No difference was found in t he allelic frequencies for any of the CTGB33 alleles or the HLA-A alleles. As there were a number of differences between this study and that of Plomin 's group, this can only be viewed as a limited attempt at replication. (C) 1999 Elsevier Science Ltd. All rights reserved.