High-throughput genotyping on archived dried blood spot samples

The aim of this study was to investigate if dried blood spot (DBS) samples stored in the Danish Neonatal Screening Biobank (DNSB) and the Danish National Birth Cohort (DNBC) repository are useful for Illumina single-nucleotide polymorphism (SNP) genotyping. Genomic DNA (gDNA) was extracted from just one 3.2 mm DBS punch. The extract was subsequently whole-genome amplified to meet the required amounts of DNA for genotyping. For evaluation of the biobank samples, we included variable factors: time of storage, gDNA, and whole-genome amplified DNA (wgaDNA) concentrations and the Illumina quality metric (GenCall score). The custom 1152 SNP genotyping assay had a 68.5% locus success rate, which was close to the expected 70%. An effect of storage condition was seen in the DNSB samples stored from 1982 to 1987, whereas none was seen in the samples stored from 1988 to 1990. The genotyping quality of the DNBC samples was affected by type of filter paper. We here demonstrate that high-throughput Illumina genotyping can be performed successfully on wgaDNA made of gDNA extracted from only one 3.2 mm DBS disk. This validates the vast potential of existing biobanks in the study of the role of gene interactions in complex diseases.