Rapid direct PCR for ABO blood typing

Many different molecular typing methods have been reported to complement routine serological ABO blood typing in forensics. However, these ABO genotyping methods are often time-consuming and call for an initial DNA isolation step that requires the use of expensive kits or reagents. We report here a rapid direct ABO genotyping method that eliminates the need for DNA extraction from fresh blood, hair, and body fluid stains before PCR. Using a fast PCR instrument and an optimized polymerase, the genotyping method-which employs a multiplex allele-specific primer set for the simultaneous detection of three single-nucleotide polymorphism (SNP) sites (nucleotides 261, 526, and 803)-identifies A, B, O01/O02, O03, and cis-AB01 alleles in around 70 min from sample collection to electropherogram. Not only will this ABO genotyping method be efficiently used in forensic practice for rapid screening of samples before full-blown multilocus short tandem repeat profiling, but it will also demonstrate an example of rapid direct genotyping of SNPs that offers the advantages of time- and cost-efficiency, convenience, and reduced contamination during DNA analysis.