example depression and schizophrenia) from their control groups.16,22 Li and colleagues excluded such patients, but these authors relied on subject’s self-reported medical history, rather than formal psychiatric evaluation, which may have failed to exclude control subjects who in fact had psychiatric illness(es).18 All studies genotyped their subjects by means of the PCR or one of its variants (such as restriction fragment length polymorphism, denaturing high performance liquid chromatography, or allele-specific PCR), except that of Hoehe and colleagues, who used a novel multiplex sequence comparison technique.17
