Messenger Rna Profiling: Body Identification Using Multiplex Real-time Pcr

Conventional methods of body fluid identification use labor-intensive, technologically diverse techniques that are performed in a series, not parallel, manner and are costly in terms of time and sample. Furthermore, for some frequently encountered body fluids no confirmatory technique exists. There is no definitive test, for example, for the presence of saliva or vaginal secretions. In seeking to develop novel multiplex (i.e. parallel) analysis procedures for body fluid identification that are compatible with current DNA analysis procedures, we have chosen assays based upon messenger RNA (mRNA) since it is expressed in a tissue type specific manner. Terminally differentiated cells, such as blood lymphocytes, ejaculated spermatozoa, or epithelial cells lining the oral cavity, have a unique pattern of gene expression, which is evinced by the presence and relative abundance of specific mRNA species. If the type and abundance of mRNAs can be determined in a stain or tissue sample recovered at the crime scene, it would be possible to definitively identify the tissue or body fluid in question. Advantages of an mRNA-based approach, compared to conventional biochemical analysis, include greater specificity, simultaneous and semi-automated analysis though a common assay format, improved timeliness, decreased sample consumption and compatibility with DNA extraction methodologies.