Non-invasive harvesting of DNA
DNA can be harvested non-invasively from cells at the inside of a person´s cheek using buccal swabs – but these specimens resemble heterogeneous mixtures of buccal epithelial cells and leukocytes. The percentages of leukocytes vary between 5% - 60% in buccal swabs and 16% - 95% in mouthwash samples (saliva), the rest largely consists of buccal epithelial cells.
The cellular composition is relevant
The cellular composition needs to be considered for various applications – particularly for epigenetic analysis since the epigenetic makeup differs significantly between different cell types. For example, epigenetic age predictions based on buccal swabs become more precise with this additional information.
How does it work?
Using multiple genome-wide datasets we have identified two genomic regions that are specifically methylated either in buccal epithelial cells or in leukocytes (associated with the genes CD6 and SERPINB5). We developed a pyrosequencing assays for two CpG sites located in these regions. These measurements are combined in the “Buccal-Cell-Signature” to facilitate robust estimates of the cellular composition. The Buccal-Cell-Signature can be combined with the Epigenetic-Aging-Signature to improve the precision of age-predictions in buccal swabs.
Patent application: DE 10 2016 109 291.6