In terms of general cognitive functioning, 9/11 individuals with 15q11.2 BP1-BP2 microdeletions performed in the average to superior range; whereas, one affected child (Subject 3) scored just below the normal range for full-scale IQ, and one affected child (Subject 11) was unable to complete cognitive testing due to limited receptive and expressive language understanding and severe developmental delay. The gene discussed is IGFBP2; the disease is Global developmental delay.