Analysis of eight children with ADHD and three controls genotyped in duplicate established perfect concordance between CNVs larger than 200 kb called in the duplicate samples (n=9). Analysis of CNVs called in 45 HapMap CEU samples (Utah residents with ancestry from northern and western Europe) that had been genotyped and supplied by Illumina with both the Human660W-Quad and HumanHap550 BeadChips also showed 100% concordance between the 12 rare CNVs larger than 200 kb identified. We noted no significant differences in the frequency of large rare CNVs between samples extracted from blood and those extracted from saliva, or in the frequency with which CNVs were called in male compared with female participants in either the ADHD or control groups (all data available from NMW). Finally, as a highly conservative measure we accepted for analysis only CNVs larger than 500 kb. Large CNVs are called with greatest accuracy and show good concordance across different platforms.11,24 Large CNVs also show the most robust evidence for association with neurodevelopmental disorders such as schizophrenia.9–11,22
