Criminology Research Council grant ; (19/89)
The results of this research are given in a summary report and a number of journal articles which have been bound in one volume. The objectives of the research were to (1) develop methods of detecting genetic variation at HLA Class II genes for the purpose of individual identification in the context of forensic investigations, with particular emphasis on the HLA DPB1 gene; (2) determine the frequencies of these genetic variants in an Australian Caucasian sample; and (3) identify and characterise any new genetic variants that might be detected in the above sample or in the course of other work and develop routine methods for detecting these.
The initial objectives of the project have all been achieved. When the project began there were 19 HLA DPB1 alleles officially recognised by the World Health Organization. A simple and accurate method of detecting these alleles was developed. The method is based on amplification of the variable portion of the DPB1 gene by the polymerase chain reaction (PCR) followed by restriction enzyme digestion of the PCR product at sequence-specific restriction sites. The method, now commonly referred to as PCR-restriction fragment polymorphism (RFLP) analysis, has a number of advantages over alternative typing methods in terms of accuracy, reliability, efficiency and sensitivity that are particularly relevant in the context of forensic investigations. The reliability of the method has been tested by applying it to the typing of cell lines prepared for the Tenth International Histocompatibility Workshop, that had previously been typed by other methods.
There are now 44 recognised HLS-DPB1 alleles and the typing method has been modified and updated to enable all the new alleles to be detected. The principles on which the typing method is based are explained. The HLA-DPB1 typing method has been applied to samples of unrelated individuals from ten populations from the Asia-Pacific region and the frequencies of the different alleles have been determined. In the process, a number of new alleles were discovered.
HLA-DPB1 is one of the most polymorphic genes in the human genome and therefore of great potential use in forensic DNA typing. With 44 known alleles it is, for example, much more polymorphic than HLA-DQA1 at which only six alleles are routinely detected in forensic typing. A reliable and efficient method of detecting variation at this locus has now been developed. The method is based on simple routine procedures and requires very little in the way of specialist equipment or reagents. It is already proving useful in clinical applications and should be equally useful in a forensic context.