Laser scanning microdissection - Advantages and pitfalls in forensic diagnosis.

• Type: Chapter or Part of a Book
• Date: 2017

Authors

Laura Cainé (Collaborator) FMUP

Book

Title: Microscopy and imaging science: practical approaches to applied research and education

Electronic ISBN: 8494213490, 9788494213496

Other information

Authenticus ID: P-017-DSV

Abstract (EN): Laser microdissection (LMD) is a technology that has been around for more than 40 years. It combines the amplification power of a microscope with the precision cut of objects allowed by the laser technology. The main use of a Laser Microdissection System (LMS) is for clinical purposes, in order to isolate cells or its components of interest. Only in the last decade has LMD been used for forensic purposes, mainly in sexual assault casework for isolating sperm cells from vaginal swabs. Sexual assault cases are among the most difficult scenarios that forensic laboratories have to deal with. Several factors impact the achievement of a result that either implicates or exonerates a suspect. Among these factors, the most important are the quality of the sample, the amounts of DNA present or even their relative proportions in a mixture. Sometimes the interpretation of the mixture is complex, mainly without reference samples from the victim and the suspect. The LMD technology allows the selection of individual cells based on morphology (e.g. sperm cells opposed to epithelial) or on labeling with specific fluorescent dyes for posterior analysis. Mixture analysis with an azoospermic or oligospermic contributor is even more challenging. In the absence of sperm cells, male and female cells are indistinguishable, requiring the use of specific fluorescent dyes. The use of these techniques can also pave the way for detection of enough cells for analysis. Here we try to gather the main options to undertake laser microdissection analysis in forensic casework, highlighting in particular the pros and cons of combining LMD with fluorescence identification of interest specimens to increase accuracy and to speed-up isolation.

Language: English

Type (Professor's evaluation): Scientific