In this largest study to date (1), established schizophrenia risk variants accounted for 49% (17 of 35) of the copy number variants of definite clinical significance discovered in 3,822 karyotypically normal pregnancies. These included a 1q21.1 deletion, a 15q13.3 deletion, four 17q12 deletions, and 11 typical 22q11.2 deletions (6, 7). All but one were de novo mutations. Fourteen (23%) of 61 additional copy number variants reported to patients as having the potential for clinical significance are associated with schizophrenia: three 1q21.1 duplications, one 2q13 duplication, one 15q11-q13 duplication, four 16p13.11 duplications, and five atypical 22q11.2 deletions (5–7). Thus, at a minimum, one in every 124 prenatal samples (31/3,822) sent for clinical chromosomal microarray analysis would be reported as having a clinically significant finding that might also be considered a schizophrenia risk variant. Notably, a typical 22q11.2 deletion was found in one in every 347 prenatal samples (including one in every 1,022 samples with no anomaly on ultrasonography). The true incidence of 22q11.2 deletions in live births remains unknown (8). Analyses of data from other smaller studies of prenatal chromosomal microarray analysis yielded comparable results (data not shown).