Laboratory diagnosis is essential to determine the (sub)type of EB and the precise cause for it at the genetic and protein levels. There are two main methods used in EB laboratory diagnosis: genetic testing and skin sample analysis.
To perform genetic testing, blood samples are taken from the person with EB and their parents. The samples are used for the extraction of genomic DNA, which contains all the information on our individual genetic make-up. Each gene carries a unique sequence code that has a specific function as a protein. A disease-causing variant in EB-associated genes can be detected by Sanger sequencing (SS) of a specific gene or by next generation sequencing (NGS), which can analyse ALL the EB genes at once.
SKIN SAMPLE ANALYSIS
This analysis looks at changes in protein expression, localisation, and ultrastructural modifications (changes in skin components that can only be seen by electron microscopy). Immunofluorescence Mapping (IFM) examines the proteins in the skin. EB-associated proteins can be recognised by specific (antibodies) reagents. When compared to a normal skin sample, this technique can show an absent or reduced protein amount. Transmission Electron Microscopy (TEM) is used to directly examine the structural components of the skin, which cannot be seen with a conventional microscope. TEM allows samples to be magnified by as much as 10 million times. It is rarely used in standard EB diagnosis but it can be useful in solving difficult cases.