Postmortem mRNA profiling II: Practical considerations.

Using human postmortem tissues for gene expression studies is particularly challenging. Besides the problem of impaired RNA one has to face a very high degree of biological variance within a sample set. Variations of individual parameters like age, body mass, health, but also the cause and circumstances of death and the postmortem interval lead to a rather inhomogeneous collection of samples. To meet these problems it is necessary to consider certain precautions before starting a gene expression project. These precautions include the sample collection and the determination of the RNA integrity, the number of replicates needed and the methods used for reverse transcription and quantitative polymerase chain reaction, but also the strategy for data normalisation and data interpretation. In this article practical issues are discussed to address some of the problems occurring in the work with postmortem human samples obtained during medico-legal autopsy.