Opposites attract: how DNA determines who suffers from eczema and who develops psoriasis

Published On Mon 12 Jan 2015 by Grant Hill

New research led by experts from the University of Dundee, working with colleagues from England, Ireland, Germany and the USA, has shown for the first time why some people develop eczema and skin allergies whilst others are prone to psoriasis.

Eczema and psoriasis are among the most common skin conditions. Eczema affects up to one quarter of school-aged children in the UK and 1 in 50 people may suffer from psoriasis. These skin conditions may appear to be similar – they both produce red, itchy, scaly patches on the skin – but specialists know that patients very rarely have both the conditions together at the same time.

The new study, published in the American Journal of Human Genetics, involved over 19,000 people who had given DNA for research into the genetic causes of eczema and psoriasis. Researchers used computer statistical analysis to test across the whole genome for differences in the DNA of patients with eczema compared with psoriasis patients, to look for what causes these diseases to occur separately.

Dr Sara Brown, Clinical Senior Lecturer and Consultant Dermatologist at Dundee’s School of Medicine, said, “We know that eczema and psoriasis are diseases which both cause inflammation of the skin, but we wanted to find out why the people who suffer from eczema appear to be protected against psoriasis, and vice versa.

“This is the first study to compare the two skin diseases. Large numbers of patient samples were needed because of the complexity of DNA sequence across the whole genome, so my team in Dundee needed to work with international researcher groups to gather a sufficient number of samples.”

This careful comparison of the DNA of eczema and psoriasis patients has shown important differences between the two diseases, particularly in regions of the DNA which control the structure of skin, making it an effective barrier against the outside world.

There were also differences in the DNA controlling immunity to infection and inflammation, which may explain why eczema patients are prone to develop skin infections, as well as asthma and hay fever, whilst skin with psoriasis is protected against infection.

Dr Brown added, “The results of this study have given us new information to explain why the skin inflammation in eczema patients is fundamentally different from those with psoriasis. This may be the key to developing new and more targeted treatments for these skin conditions which can each have a devastating impact on life.”

Dr Brown’s research was funded by the Manknell Charitable Trust, The Tayside Dermatological Research Charity and the Wellcome Trust.

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