DNA extraction and HLA genotyping using mailed mouth brushes from children

The need for blood samples in genetic epidemiologic studies often leads to low response rate among non-diseased individuals, and the collection of blood samples is costly and labor-intensive. We tested the feasibility of extracting DNA for human leukocyte antigen (HLA) typing from buccal cells collected with mailed, self-administered mouth brushes. A random sample of 1474 Norwegian children aged 0-17 yr was contacted by mail and received information about the study and mouth brushes for buccal cell samples. Brushes were returned by mail, DNA was extracted and the HLA-DQA1 and -DQB1 allelic polymorphisms were determined using polymerase chain reaction (PCR) and sequence-specific oligonucleotide probes. Mouth swabs were returned from 1068 (72.5%). Of these, DNA was extracted and HLA typing successfully completed for 1056 individuals (98.9%). In conclusion, we have described an efficient and safe set of methods for application in genetic epidemiologic studies of type 1 diabetes and other HLA-related diseases. A large proportion of randomly selected children returned self-administered mouth swabs with DNA of sufficient quality and quantity for HLA genotyping.