Parent / Patient /GP Information sheet
X-linked Lymphoproliferative Disease
(Duncan’s syndrome)
How Common is XLP?
XLP is extremely rare, and only about 100 families with XLP
are known to exist worldwide.It is
likely, however, that there are many more individuals whose disease is as yet
unrecognised.
What are the features
of the condition?
XLP can have many different symptoms, and we do not yet know
what the full spectrum of the disease is.About a third of patients have a very severe episode of glandular
fever.Another third develop a cancer of
their blood cells (lymphoma) and another third have low levels of
immunoglobulin, the proteins in the blood that help fight infection.More rarely, individuals may have a severe
form of anaemia or inflammation of small blood vessels (vasculitis).It is common for one individual to have
several different symptoms over the course of their illness.
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What are the symptoms?
Severe glandular fever
Lymphoma: Patients may be tired, anaemic and develop swollen glands.
Hypogammaglobulinaemia: Patients may get frequent infections.
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What causes the condition?
The cause of the condition was only found in 1999, so there
is much that we do not understand about it.It is caused by a mutation, or mistake, in one of the genes on the X
chromosome.This means that the cell
does not get the right instructions it needs to work properly.In most families, the mistake is in a gene
called SH2D1A.This gene normally makes
a protein called SAP.Mistakes in the
gene cannot be found in a number of individuals with the disease, and we are
looking hard to find out which gene is responsible in these families.
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Pathogenesis
We think that the immune system in XLP is unable to cope
with some viral infections, in particular EBV.The immune system loses its normal tight regulation, and starts to
malfunction.
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How is the condition inherited?
The X chromosome is one of the sex chromosomes: females have
two X chromosomes and males have one X and one Y.Each X chromosome carries one copy of the
gene.If a male has a faulty gene on
their X chromosome, they will have the disease.However, because the female has two X chromosomes, the normal gene on
one X can compensate for the faulty one on the other.Thus, only males get the disease, and females
may carry the disease but be unaffected. This is an “X-linked disease” and
within a family tree you may be able to pick out other affected males.You can find more information about genetics
in other leaflets.
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Are all the children in the family affected?
No! If a mother carries the disease, each time she has a
female child, there is a 50% chance that they will be a carrier.Each time that she has a male child there is
a 50 % chance that they will be affected by the disease.
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How is the diagnosis made?
The diagnosis will be suggested by the pattern of illness in
the child and their family.In most
children we can confirm the diagnosis using a blood test.This will check if the protein (SAP) that makes
the cells work properly is present, and will also look for the “mistake” in the
gene.In some families there may not be
a mistake in this particular gene, and the diagnosis can be made on the
clinical story alone.
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What treatment can be given for the condition?
Initially treatment will be given for the symptoms that your
child presents with, this may include anti-viral medicines, immunoglobulin
therapy or steroids.Children may
receive a variety of supportive treatments, such as immunoglobulin and
antibiotics to keep them well in the short term.Bone marrow transplantation is the definitive
treatment of choice at the present time.This can be a difficult procedure, requiring a prolonged hospital stay.
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What is the outlook for people with the condition?
70% of individuals with XLP die by the age of 10 years
without any treatment.However, as we
are learning more about the disease we are identifying adults with milder forms
of the condition.
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Is there a support group?
The primary immunodeficiency association offers advice and
support for all families with immune deficiency in the UK.Their contact details are:
www.pia.org.uk.