Forensic Services
Low Copy Number (LCN) DNA analysis
Low Copy Number (LCN) is a much more sensitive form of the conventional DNA analysis used routinely in forensic casework. Conventional forensic DNA analysis targets specific areas of chromosomes within the cell nucleus that show great variation between different individuals. These specific areas contain a short, repeating pattern of DNA and are called Short Tandem Repeats (STRs).
Low Copy Number (LCN) can be an extremely useful technique to analyse extremely small traces of DNA. The increased sensitivity afforded by LCN can result in a DNA profile being generated when the routine form of DNA analysis has either failed to generate a DNA profile or has generated an incomplete DNA profile.
LCN is such a sensitive technique that it is only used when all other techniques have been attempted. Interpretation of LCN DNA profiles can be more complex than that following routine DNA analysis techniques and this form of analysis is only used in exceptional cases. Improvements in routine DNA analysis techniques have resulted in the ability to generate DNA profiles even when DNA is present in very small amounts (e.g. from handled items such as weapons and discarded tools). These improvements have reduced the requirement to use this even more sensitive form of DNA analysis but it is still a very useful technique to be able to turn to when all else has been attempted.
A typical casework example where LCN analysis might be considered is in cold case reviews where there may be very limited material available and considerable thought must be given to how best to proceed with what material is left. Cold case reviews are unsolved cases which may date back many years and any DNA remaining may, as a result, be in poor condition. After all efforts have been made to obtain DNA profiles by conventional methods, the LCN technique might be considered if these initial efforts have failed or incomplete profiles generated.
Very careful consideration needs to be given to the use of the LCN DNA analysis technique so that it is used appropriately. Cellmark has developed other techniques that can be used to increase the sensitivity of DNA analysis as an alternative to LCN but recognises that in exceptional circumstances and used appropriately, LCN can be an extremely valuable technique.
