Whole genome amplification of DNA extracted from hair samples: potential for use in molecular epidemiologic studies

Because of concerns regarding the quality and quantity of DNA isolated from human hair, such samples are often overlooked as a source of DNA for molecular epidemiological studies. Nevertheless, there are many potential benefits to using hair: it is easily self-collected; it does not require costly collection kits; it can be mailed for a nominal fee; and the hair specimens can be stored at room temperature. However, the amount of DNA that can be extracted from hair samples is somewhat limited. Therefore, we assessed the feasibility of using whole genome amplification (WGA) on genomic DNA extracted from archived human hairs (stored for 7 to 11 years) to increase the quantity of DNA available for genotyping analysis.

We evaluated two methods of WGA, multiple displacement amplification and the Genomeplex method. Both WGA methods were performed on each of 44 DNA samples isolated from archived human hair specimens. The resulting WGA products where then screened for the presence of three single nucleotide polymorphisms. The genotyping results were compared to genotyping data obtained from DNA isolated from mouthwash samples collected from the same individuals.

When we focused on DNA extracted from the hair root, we observed excellent agreement between the genotypes determined from both the hair (pre-WGA) samples and Genomeplex WGA when compared to their corresponding mouthwash DNA samples (kappa=0.83-0.91 and 0.79-0.92, respectively); whereas the agreement between the MDA samples and mouthwash DNA samples was poor (kappa=0.27-0.51).

Our data suggest that, when combined with Genomeplex WGA, hair specimens containing the root portion can serve as a reliable and renewable source of DNA.