AUTOIMMUNE DISEASE:
There are a large number of
autoimmune diseases which can
affect almost any organ in the
body, either singly or several
at a time. It is well documented
that two particular autoimmune
diseases are more common in
Down's Syndrome; autoimmune
thyroid disease and celiac
disease.
Autoimmune thyroid
disease:
The thyroid is a gland in the
neck, which produces hormones
controlling metabolism and thus
energy production. In autoimmune
thyroid diseases the gland is
gradually destroyed leading to
marked changes in behaviour
which is usually associated with
lack of energy (hypothyroidism)
but sometimes with over-activity
(hyperthyroidism). These
diseases usually affect
middle-aged women. It has been
recognized for many years that
even young people with Down's
Syndrome (male or female) can
suffer from thyroid dysfunction,
which can often be attributed,
particularly in those over
eight, to autoimmune thyroid
disease. Since the symptoms of
thyroid disease share some
similarity with those associated
with Down's Syndrome, it is
often missed. Simple laboratory
blood tests (Thyroid Stimulating
Hormone, free or total T4)
readily detect abnormal thyroid
function. In autoimmune
thyroiditis, the characteristic
autoantibodies, anti-TSH
receptor and anti-thyroid
peroxidase antibodies (formerly
anti-thyroid microsomal
antibodies) are also easy to
measure. Children and adults
with Down's Syndrome should be
screened regularly for thyroid
function. Thyroid dysfunction is
readily corrected by hormone (thyroxine)
replacement, taken orally
Cœliac disease
Cœliac disease is an
immunologically mediated
intolerance to a group of wheat
proteins called gluten (gliadin).
This generates an autoimmune
disease which damages the
absorptive surfaces of the
intestine causing the loss of
villi leading to malabsorption
of nutrients which can result in
weight loss, lethargy and
anaemia.
Other autoimmune diseases
and allergy:
There have been a number of
less definitive studies
concerning diabetes and less
common autoimmune diseases (
hypoparathyroidism, alopecia)
which might be more prevalent in
people with Down's Syndrome. A
gene associated with autoimmune
polyglandular syndrome which can
cause these diseases is located
on chromosome 21. There have
been surprisingly few studies of
the relative incidence of
allergy in Down's Syndrome. It
should be remembered that in
contrast to infectious disease,
the overall incidence of
autoimmune disease and allergy,
in particular, is increasing
dramatically in the developed
world.
Leukemia:
Leucocytes, are the essential
cells of the immune system.
There are many different types
of leucocytes each playing a
specific role in immunity.
Perhaps because they are so
active, leucocytes are
apparently more prone to
developing the cellular damage
which leads to cancer. Leukemias
are one group of malignancies of
white cells which, like most
cancers, are more common in the
elderly. There are many types of
leukaemia and at least two are
more common in Down's Syndrome.
These are acute lymphoblastic
leukaemia (ALL) and acute non-lymphoblastic
leukaemia (ANLL). The latter is
far more common in very young
children with Down's Syndrome.
The former, which is also more
common in Down's Syndrome
usually affects children. |