Among the 14 novel ID/DD CNV-loci, we identified a 660 kbp deletion mapping to chromosome 15q25.2 flanked by SDs (69.8 kbp, 98.6% identity) (Figure 3A). The deletion is absent in the controls analyzed here and the Database of Genomic Variants (http://projects.tcag.ca/variation/), but present in five affected individuals (including two siblings) among the ID/DD sample set. Clinical aspects of the probands were variable consisting of neurologic features and DD (Supplementary Table 9); one female had only mild motor delay associated with a congenital myopathy but was otherwise cognitively normal. The two brothers with the deletion both had autism spectrum disorders but additional family members were not tested (Supplementary Note). A previous meta-analysis of patients found this deletion in 4 of 6,860 cases16 with schizophrenia and autism compared to 0 of 5,674 controls (combined with this study, p = 0.037 after excluding one sibling). Thus, while statistical significance remains modest and population stratification cannot be definitively ruled out (see Supplementary Note), these data suggest a potentially new genomic disorder that will be observed at a frequency of 1/3,000 referred cases.
