Gene Expression And Protein Profiling -- Can They Prove Causation In Toxic Tort Cases?
July, 2008
Introduction
An exciting new development in toxic tort litigation is the use of gene expression and protein profiling to prove or disprove whether a toxic agent, such as benzene, has caused the claimant’s injury.Cells are the fundamental unit of the human organism. The chemical DNA within the cell’s nucleus contains the instructions to direct the cell’s functions. DNA is packaged into 46 chromosomes. Each chromosome contains many genes. The genes encode instructions on how to make proteins. Proteins are large complex molecules made up of amino acids. The proteins make up cellular structures and define particular functions. Cytokines are a category of signaling proteins used extensively in cellular communication. They are often secreted by immune cells that have encountered a pathogen, and activate and recruit more immune cells.
Discussion
Recent developments in technology allow scientists to monitor the expression of thousands of genes and to profile the production of certain proteins. Genes are up regulated or down regulated to “express” their intended function. Proteins may or may not exist in a serum sample. Proponents state that they can compare samples from a claimant to samples created in the lab that have been exposed to benzene metabolites. If the claimant’s sample matches the lab’s sample, then they conclude that benzene affected the claimant’s samples. If no match resulted, then they conclude that benzene did not cause the claimant’s condition. Thus, they posit that their tests can confirm or refute causation.The study of gene expression has been available and used for other medical reasons for several years. For example, doctors use this information to choose among various treatment regimens for certain diseases. The use of gene expression as a possible tool in injury claims and litigation; however, is a recent development.
Researchers have exposed, in vitro, treated serum samples from eight individuals to benzene metabolites, and believe that they see a resulting gene pattern in the cell’s DNA that is unique to these chemical agents. Certain genes express themselves by turning on or off after exposure to the metabolites. Protein profiling is based upon the belief that extracellular cytokines will be produced by certain blood cells exposed to the benzene metabolites. The results of both the gene expression and the protein profiling differ from the standard human gene expression and protein profiling. Researchers propose that this difference represents the unique signature of benzene acting on the human cell.
Bruce Gillis, M.D. and founder of the Cytokine Institute, claims that the benefits of this evidence are that early identification of a benzene response in the cell will lead to early settlements of claims and avoid protracted and expensive litigation. Gillis similarly suggests that a negative finding will provide the defense with powerful medical evidence that benzene did not cause the injury.
Opponents of gene expression and protein profiling evidence proffer several arguments to support their conclusion that it is junk science. First, they argue that the initial methodology was flawed. The sample size of only eight subjects, the blending of their serum samples, and the in vitro mode of testing are criticized. Second, critics also question whether patterns can only be unique to benzene when it is the only agent tested. Stated another way, would not thousands of agents have to be tested before one could conclude that a pattern is unique to only one agent - benzene. Finally, opponents state that gene patterns change, and that conclusions based upon a sample taken and compared at a single point in time can lead to erroneous conclusions in both directions.
Learning Point
To date, no court is known to have considered the admissibility of gene expression and protein profiling evidence. The procedure will have to pass Frye or Daubert challenges in future litigation. Arbitrators in workers’ compensation hearings are reported to have considered the evidence in three instances; but this obviously is not precedent in any state court’s common law tort action. Toxic tort claim handlers are advised to consult the evolving scientific literature and competent legal counsel in order to keep abreast of the developments in this important area and its ability to help or to hinder their claim handling efforts.Back to CM Report of Recent Decisions (2008v2) 2008 Volume 2 Table of Contents
