Pediatric Diabetes 2002: 3: 89–94 Copyright C Blackwell M unksgaard 2002 Printed in Denmark. All rights reserved Pediatric Diabetes ISSN 1399-543X Original Article DNA extraction and HLA genotyping using mailed mouth brushes from children Witsø E, Stene LC, Paltiel L, Joner G, Rønningen KS. DNA extraction Elisabet Witsø a , and HLA genotyping using mailed mouth brushes from children. Lars C. Stene a,b , Liv Paltiel a , Pediatric Diabetes 2002: 3: 89–94. C Blackwell Munksgaard, 2002 Geir Joner b and Kjersti S. Rønningen a Abstract: The need for blood samples in genetic epidemiologic studies a Division of Epidemiology, Norwegian often leads to low response rate among non-diseased individuals, and the Institute of Public Health, and b Diabetes collection of blood samples is costly and labor-intensive. We tested the Research Center – Aker and Ullevål feasibility of extracting DNA for human leukocyte antigen (HLA) typing University Hospitals, Department of from buccal cells collected with mailed, self-administered mouth brushes. Pediatrics, Ullevål Hospital, Oslo, Norway A random sample of 1474 Norwegian children aged 0–17yr was contacted by mail and received information about the study and mouth brushes for Key words: buccal cells – children – buccal cell samples. Brushes were returned by mail, DNA was extracted and genetic epidemiology – human leukocyte the HLA-DQA1 and -DQB1 allelic polymorphisms were determined using antigen – laboratory methods – population polymerase chain reaction (PCR) and sequence-specific oligonucleotide studies probes. Mouth swabs were returned from 1068 (72.5%). Of these, DNA Corresponding author: Lars C. Stene, was extracted and HLA typing successfully completed for 1056 individuals Division of Epidemiology, Norwegian (98.9%). In conclusion, we have described an efficient and safe set of Institute of Public Health, PO Box 4404 methods for application in genetic epidemiologic studies of type 1 Nydalen, N-0403 Oslo, Norway. Tel: π47 23 40 81 76; fax: π47 22 35 36 05; diabetes and other HLA-related diseases. A large proportion of randomly e-mail: lars.christian.stene/folkehelsa.no selected children returned self-administered mouth swabs with DNA of sufficient quality and quantity for HLA genotyping. Submitted 16 November 2001. Accepted for publication 15 March 2002 Studies of genetic susceptibility or gene–environment interactions in the etiology of complex diseases need to take epidemiologic principles into consideration (1). The traditional case–control study is a commonly used design in genetic epidemiology (2). An import- ant contribution to genetic susceptibility for autoim- mune diseases such as type 1 diabetes comes from the highly polymorphic human leukocyte antigen (HLA) complex located at the short arm of chromosome 6 (6p21.3), and type 1 diabetes is believed to result from a combination of genetic and non-genetic factors (3). Previous case–control studies of genetic susceptibility for autoimmune diseases have mostly used blood do- nors as control subjects (4). Some authors have ar- gued that use of blood donors instead of controls se- lected from the population may lead to bias (5). En- vironmental risk factors are likely to be more sensitive to valid selection of population control sub- jects. Population-based controls are therefore import- ant in studies of gene–environment interactions (6). The motivation for participation among randomly 89 selected individuals may be low if they have to pro- vide a blood sample, particularly among children. The resources necessary for collection of a large num- ber of blood samples from dispersed populations may be prohibitive. Non-invasive, self-administered methods for collection of DNA may circumvent some of these problems. Several studies have shown that DNA isolated from buccal cell samples is adequate for a wide range of polymerase chain reaction (PCR)- based assays (7–12). For instance, Richards et al. (7) have analyzed the CFTR gene, Gillespie et al. (8) have anayzed polymorphisms in the HLA class II re- gion, and several authors have analyzed polymorph- isms relevant for metabolic detoxification (13, 14). Those studies comparing results from buccal cells and blood have generally found a very high concord- ance. Although the validity and feasibility of geno- typing based on DNA extracted from buccal cells has been demonstrated before (7–12), we are not aware of any previous study of the feasibility of using mailed, self-administered mouth brushes for DNA