Standard CYP2D6 genotyping procedures fail for the CYP2D6*5 and duplication alleles when hair roots are used as a source of DNA

BACKGROUND: Hair roots provide a useful alternative to blood as a source of DNA for genotyping. Besides simple and non-invasive collections, the DNA extraction step is also easy to perform and is fast. The aim of our study is to determine if hair roots can be used to genotype all of the common CYP2D6 alleles for routine screening purposes.

METHOD: The study complies with the Declaration of Helsinki. After obtaining informed consents, both blood and hair samples were collected from 92 patients for genotyping of the CYP2D6 gene. PCR was used to detect the following mutations: CYP2D6*1, *3, *4, *5, *9, *10, *17 and duplication gene. The results were compared where hair roots and blood were used as templates for DNA respectively.

RESULTS: When blood was used as a source of DNA for genotyping, all of the investigated CYP2D6 alleles were successfully amplified. However, with hair roots, the genes with the larger fragment sizes: CYP2D6*5 and the duplication gene could not be amplified and the bands of other alleles investigated were faint when visualized under UV light.

CONCLUSIONS: DNA extraction from hair roots and leucocytes yielded similar results but the DNA extracted from hair roots did not allow successful amplification of the longer genes such as the CYP2D6*5 and the duplication gene.