基因,蛋白,免疫 课程5.ppt

Genomics 5 Forensic Pathology/DNA profiling Some Uses of DNA Profiling Criminology Anthropology- Evolution. Migration of populations. Diseases present in ancient civilisations eg Chiribaya Indian History-Russian Royal Family Zoology- Monitoring of migration and breeding patterns of endangered species (captive breeding programs). Conservation: Poaching, ivory trade. Sample preparation Types of marker Determining sex Theoretical considerations Cases The HLA DQA1 Based on polymorphisms of Human Leucocyte Associated (HLA) antigens which are located within the Major Histocompatibility Complex (MHC) on the short arm of chromosome 6. First system to become available for forensic analysis based on PCR Region is polymorphic Original probe set detected six common DQ? alleles. As for blood groups, excellent for excluding suspects but has limited power for proof of identity because only one locus with limited variability is analysed. * Collection of biological samples from the scene of the crime is of paramount importance to maximise the amount of the biological sample retrieved and minimise contamination with adventitious agents. Recovery of Biological Samples Types of biological samples Blood stains Saliva Semen Swabs Hair roots Hair Recovery of a blood stain Blood samples rovide a high proportion of samples in forensic studies. This analysis relies on DNA extracted from white blood cells as red blood cells are enucleate. Both mitochondrial and nuclear DNA can be analysed . Blood Samples Depressingly, a high proportion of forensic cases involve sexual assault. Forensically, sperm are not depressing because they can be easily purified from other cell types as a result of highly packed DNA. Spermatazoa Tandem repeats Sequence polymorphisms Types of Difference Between Individuals Analysed by Forensic DNA Typing Systems Amounts of DNA Fresh material eg blood stains yield more DNA and is likely to be less degraded. Less semen or saliva is required than blood RFLP