Inherited epidermolysis bullosa

Inherited epidermolysis bullosa (EB) encompasses a number of disorders characterized by recurrent blister formation as the result of structural fragility within the skin and selected other tissues. All types and subtypes of EB are rare; the overall incidence and prevalence of the disease within the United States is approximately 19 per one million live births and 8 per one million population, respectively. Clinical manifestations range widely, from localized blistering of the hands and feet to generalized blistering of the skin and oral cavity, and injury to many internal organs. Each EB subtype is known to arise from mutations within the genes encoding for several different proteins, each of which is intimately involved in the maintenance of keratinocyte structural stability or adhesion of the keratinocyte to the underlying dermis. EB is best diagnosed and subclassified by the collective findings obtained via detailed personal and family history, in concert with the results of immunofluorescence antigenic mapping, transmission electron microscopy, and in some cases, by DNA analysis. Optimal patient management requires a multidisciplinary approach, and revolves around the protection of susceptible tissues against trauma, use of sophisticated wound care dressings, aggressive nutritional support, and early medical or surgical interventions to correct whenever possible the extracutaneous complications. Prognosis varies considerably and is based on both EB subtype and the overall health of the patient

Forensic DNA methylation analysis First technical collaborative exercise by the working group on molecular age estimation of the German Society of Legal Medicine

Quantitative analysis of relative DNA methylation is currently one of the most promising methods of molecular age estimation. In recent years numerous studies identified potential DNA methylation markers showing age-dependent changes in their relative methylation state. For routine application of this method validation is an important prerequisite. One aspect of validation is the degree of comparability of analytical data between laboratories. The working group on molecular age estimation of the German Society for Legal Medicine (DGRM) conducted a first technical proficiency test comprising four age estimation markers within the genes PDE4C, EDARADD, SST and KLF14. These positions were previously characterized as age-dependent biomarkers. A total of 12 laboratories participated using pyrosequencing and/or minisequencing techniques for quantitative analysis of DNA methylation. Each laboratory received blood and buccal swab samples from three individuals of different ages. Laboratories were free in their choice of reagents and material for sequencing. Minisequencing results showed systematic deviations between laboratories, which are believed to originate from differing reagents and sequencing platforms. The results of pyrosequencing did not show clear signs of systematic deviation but did show differences in the comparability between markers. Different levels of technical problems were reported, which correlated with the amount of experience with the sequencing technology. Both systematic and specific differences between analytical data produced in different laboratory settings lead to the conclusion that while it is generally possible to transfer an age estimation method to another laboratory, a mathematical model for age estimation might need to be adjusted accordingly

Forensic DNA methylation analysis Second technical collaborative exercise by the working group on molecular age estimation of the German Society of Legal Medicine

With the discovery of age-related epigenetic changes DNA methylation (DNAm) has shown new possibilities for the estimation of the age of an individual. The method has been intensively researched and its application in forensic casework is regulated by an amendment of 81e of the German Code of Criminal Procedures (StPO). To investigate the degree of DNAm new techniques must be established and validated. This necessitates investigation of the comparability of measurement results from different forensic laboratories. In winter 2019/2020 the molecular age estimation working group of the German Society of Legal Medicine (DGRM) conducted a second proficiency test to investigate this comparability using minisequencing and pyrosequencing for quantitative analysis of DNAm. This was based on the experience from the first proficiency test in 2018/2019, the results of which are presented in this edition of the journal. The current study includes the results of DNAm analysis from 12 laboratories (in total 14 participating laboratories), some of which have used both methods. In addition, four laboratories performed an age estimation using their own marker combinations and models. As these are based on different reference data and marker combinations, no qualitative comparison of the models was done but the fundamental potential of the methodology was clarified. The aim of the interlaboratory comparison was to evaluate the comparability of the DNAm measurements and to assess possible influencing factors, such as the extraction method and the device used. The results showed that the measured DNAm values of the investigated markers can differ between minisequencing and pyrosequencing as well as within the respective method between laboratories, so that fluctuations are to be expected