Noninvasive Genotyping of Dopamine Receptor D4 (DRD4) UsingNanograms of DNA From Substance-Dependent Patients

A noninvasive DNA sampling method has been implemented collecting buccalmucosa cells by cotton wool swabs. An amount of 0.2-2 μg DNA per patient wasobtained after the phenol-extraction procedure and 0.2-2 ng DNA template wassufficient for PCR amplification of the polymorphic 48 basepair repeat region of dopaminereceptor D4 (DRD4) gene. PCR products were visualized during microfabricated electrophoretic separationby laser-induced fluorescent detection and automatic data registration. Initial data of genotyping drugdependentsubjects shows a relatively high ratio of heterozygotes, possessing either longer or shorter variantsbeside the common 4-repeat DRD4 allele.