Further assessment of control samples for mutations in HDC entailed a review of available databases and an analysis of copy-number variation among DNA samples from 10,571 persons from diverse racial and ethnic backgrounds (Table S6 in the Supplementary Appendix) with the use of three types of gene chips (CNV370-Duo, HumanHap300-v1, and HumanHap550v3, all from Illumina). A stop codon, rs35490626, was identified in the dbSNP database of the National Center for Biotechnology Information. This reported allele, one missense variant identified in a patient, and two missense variants found in controls were further genotyped in 5427 persons who had not been evaluated for Tourette's syndrome or neurologic disorders and in 986 persons who had been screened for, and found not to have, neurologic disease.
