touchDERMATOLOGY coverage from EADV 2025:
Epidermal differentiation disorders (EDDs) are a group of inherited skin conditions caused by disruptions in epidermal development.
In recent years, the field has seen major progress, with significant updates to nomenclature, classification and their management. To gain deeper insight into these developments, we spoke with Dr Antoni Gostyński (Maastricht, Netherlands), who co-chaired the EADV 2025 session (held in Paris, France on 17-20 September 2025) ‘Epidermal Differentiation Disorders (EDDs) Group: From Genes to Clinics – The Truth About EDDs in 90 Minutes’.
Q. Could you tell about the new EDD nomenclature and the most impactful changes in the updated classification system?
The earlier classification of EDDs was developed many years ago and, although valuable at the time, it was primarily grounded in clinical presentation and historical nomenclature. The names were often derived either from the clinicians who first described the condition or from analogies to animals, for example, “ichthyoses”, referring to fish.
Since then, our understanding of EEDs and their pathogenesis has advanced considerably, making it clear that an updated approach was needed. A group of experts, including myself, came together to develop a new classification system, moving beyond clinical features to focus primarily on the underlying molecular mechanisms of the disease.
The gene names are particularly important, as these are genetic diseases. We believe that classification based on pathophysiology, molecular mechanisms and genetic profiles not only encourages wider adoption of genetic testing but also facilitates the selection of appropriate therapies, especially as more treatment options become available.
Within the new classification system, diseases are grouped according to different types of molecules. For example, structural molecules such as keratins, or desmosomal molecules such as desmoplakin. Identifying the gene involved allows the disease to be placed into the appropriate group, which in turn provides a framework for selecting therapies that target the relevant pathway. This approach has the potential to support more precise treatment choices in the future.
The congenital ichthyoses guidelines were revised just a few months before the release of the new EDD classification. Whilst these conditions may still be referred to as ichthyoses, they should now be considered within the broader category of EDDs.
The original ichthyoses guidelines were published 5 years ago, and the latest update has expanded their scope with additional chapters. For example, we included new sections on the use of biologics in EDDs, future perspectives and emerging therapies, as well as guidance on vaccinations for individuals with EDDs. Importantly, we also added a chapter on prenatal testing and preimplantation diagnostics, both are topics not addressed in the initial guidelines but now receiving increasing attention.
In the session on ATP2A2-nEDD (Darier disease) and ATP2C1-nEDD (Hailey–Hailey disease), an important update was that these conditions are now included within the EDD classification, which was not the case previously. This is a positive step, as shared pathways can be recognised, facilitating collaboration between research groups working on different diseases such as ichthyoses, and enabling the exchange of knowledge and experience within one group.
A key takeaway from the session was the recognition that Darier disease should not be regarded as a skin only condition; it is a systemic disease with neurological features also involved.
For palmoplantar EDDs, research remains limited. While some studies are ongoing, there are currently no effective therapies available; however, investigational approaches, such as epidermal growth factor inhibitors, are showing potential.
From a clinical and genetic perspective, if a genetic condition is suspected, genetic testing should be performed, even in cases with very mild clinical presentation. This is important, as the findings may have implications on family planning or on the clinical picture of the child. So it’s important to do genetic testing even in mild cases.
This presentation was delivered by my colleague, and PhD student, Dr Fauve van Veen.
In dermatology, reproduction and family planning are rarely a primary focus. From our research on quality-of-life in older patients, we learned that they are real dilemmas surrounding reproduction. With that in mind, our current research is aimed at interviewing patients, dermatologists and geneticists to explore which topics are addressed, which are overlooked, and what the unmet needs are. In addition, we are also examining different methods of family planning for people with inherited diseases. The ultimate goal is to develop guidelines that will support dermatologists and clinical geneticists in addressing these issues more effectively in clinical settings.
The day before EADV 2025, we held the first Symposium on Epidermal Differentiation Disorders (EDD) in Versailles, France. During the meeting, participants worked in groups to discuss and identify the priorities for the next 5 years. A comprehensive list of priorities was generated, which will be refined through voting to around 10–15 key points. These will cover areas such as diagnostics, quality of life, education, therapies and advancing the understanding of disease mechanisms and biology. Discussions also centred on collaboration, data sharing, and the potential for working together within a consortium. It was a highly productive day, and in the coming weeks or months a meeting report outlining the roadmap will be submitted for publication.
Disclosures: Antoni Gostyński: TBC
This content has been developed independently by Touch Medical Media for touchDERMATOLOGY. It is not affiliated with the European Academy of Dermatology and Venereology (EADV). Views expressed are the speaker’s own and do not necessarily reflect the views of Touch Medical Media.
Cite: What’s new in epidermal differentiation disorders (EDDs)? touchDERMATOLOGY. September XX, 2025
Editors: Gina Furnival & Victoria Jones
About Dr Antoni Gostyński
Dr Antoni Gostyński is advancing the field of dermatology through his work on innovative diagnostic tools and therapeutic strategies. Based at Maastricht University Medical Centre, Dr Gostyński co-leads the hereditary skin diseases clinic and also practises at the Catharina Hospital in Eindhoven. His clinical and research interests centre on genodermatoses, particularly ichthyoses and palmoplantar keratodermas (epidermal differentiation disorders), and he actively collaborates with national patient advocacy groups to support those living with these rare genetic conditions.
