Tissue was provided by the Birth Defects Research Laboratory (BDRL) at the University of Washington and Advanced Bioscience Resources Incorporated (ABR; Alameda, CA). All work was performed according to guidelines for the research use of human brain tissue (ABR) or the UAGA and NOTA guidelines for the acquisition and distribution of human tissue for bio-medical research purposes (BDRL) and with approval by the Human Investigation Committees and Institutional Ethics Committees of each institute from which samples were obtained. Appropriate written informed consent was obtained and all available non-identifying information was recorded for each sample. Specimens for microarray profiling consisted of two 21 pcw females, one 15 pcw male and one 16 pcw female (Suppl. Table 1).