By Deborah Condon
The gene that causes dry, scaly skin and
predisposes people to eczema has been discovered by Irish researchers.
Furthermore this gene is also linked to
a form of asthma that occurs in association with eczema.
The research was led by Dr Alan Irivine,
a consultant paediatric dermatologist at Our Lady's Hospital for Sick Children
in Crumlin, along with Professor Irwin McLean ad Dr Frances Smith at the
University of Dundee. Professor McLean is originally from Enniskillen.
Eczema is a group of skin complaints that
can affect of all age groups and can occur anywhere on the body. An estimated
one in 10 people are affected at some point in their lives and symptoms
can include an itchy, scaly red rash.
Currently, only symptomatic treatment
of eczema is possible using emollients and ointments, which try to prevent
the skin drying out, and anti-inflammatory drugs.
However now that the underlying gene defect
behind this disorder is known, it is hoped that it will now be possible
to design more effective therapies to tackle the root cause of the problem,
rather than just the symptoms.
The gene in question produces a protein
called filaggrin, which is normally found in large quantities in the outermost
layers of the skin. This protein is essential for skin barrier function.
It helps to form a protective layer at the surface of the skin that keeps
water in and keeps foreign organisms out.
A reduction or complete absence of this
protein leads to impaired formation of the skin barrier. As a result, the
skin dries out too easily and the outer layers of the skin are poorly formed,
constantly flaking off.
In people with filaggrin mutations, foreign
substances can easily enter the skin and be seen by the immune system.
This explains the development of inflamed skin (eczema). In some people,
this 'leaky' skin appears to lead to asthma, when foreign substances later
enter the lungs.
Dr Irvine in Crumlin, along with his colleagues
in Dundee, discovered that about 10% of European people carry a type of
genetic mutation that switches off the filaggrin gene. This causes a very
common dry, scaly skin condition known as ichthyosis vulgaris.
In a second study, it was found that many
people with ichthyosis vulgaris also have eczema. Further research then
showed the link between those two conditions and asthma.
Working with colleagues in Copenhagen,
the researchers showed, in four different experiments, that these common
filaggrin mutations are a major predisposing factor in the development
of eczema and the type of asthma associated with eczema.
In fact, about two-thirds of Irish children
with eczema who were examined as part of the research, were found to carry
one or more filaggrin mutations.
The team at Dundee is already working
on developing methods to treat and even prevent these conditions.
Details of this research are published
in the journal, Nature Genetics.
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