The first sample (MRCA) contained 206 siblings of British descent (Dixon et al. 2007). Global gene expression in lymphoblastoid cell lines (LCLs) was measured using Affymetrix HG-U133 Plus 2.0 chips. All siblings were genotyped using the Illumina Sentrix HumanHap300 BeadChip (ILMN300K), the Illumina Sentrix Human-1 Genotyping BeadChip (ILMN100K), or both. The second sample (MRCE) of 950 individuals from 320 families of British descent was genotyped using the Illumina Sentrix HumanHap300 Genotyping BeadChip. Expression arrays using Illumina Human 6 BeadChips were available on 550 children. As Illumina probe and Affymetrix probesets annotated to the same gene may target different transcripts, we have first analyzed the data as individual transcripts identified by their respective Illumina or Affymetrix identification.
