Download Hereditary

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

RNA-Seq wikipedia, lookup

Vectors in gene therapy wikipedia, lookup

Gene therapy of the human retina wikipedia, lookup

Neuronal ceroid lipofuscinosis wikipedia, lookup

Genome (book) wikipedia, lookup

Site-specific recombinase technology wikipedia, lookup

Gene expression profiling wikipedia, lookup

Copy-number variation wikipedia, lookup

Gene expression programming wikipedia, lookup

Epigenetics of diabetes Type 2 wikipedia, lookup

Gene desert wikipedia, lookup

Saethre–Chotzen syndrome wikipedia, lookup

Therapeutic gene modulation wikipedia, lookup

Gene therapy wikipedia, lookup

Gene nomenclature wikipedia, lookup

Artificial gene synthesis wikipedia, lookup

Nutriepigenomics wikipedia, lookup

Designer baby wikipedia, lookup

Microevolution wikipedia, lookup

Transcript
Hereditary
Haemochromatosis (HH)
Information for Patients
Clinical Genetics
Southern General Hospital
Glasgow, G51 4TF
What is hereditary haemochromatosis?
Hereditary haemochromatosis (HH) is a treatable inherited condition where the body absorbs too much iron from
the diet. When too much iron builds up in the body this is known as iron overload. The excess iron is stored in
the liver and other organs of the body such as the pancreas, heart, endocrine (hormone producing) glands and
joints.
Why is the amount of iron in the body important?
We all need iron from our diet to make new red blood cells. This iron is stored in the liver. However, when we
have too much iron in the liver it can become enlarged and damaged. Excess iron may also be stored in the
organs mentioned above and joints, causing damage.
What are the symptoms of hereditary haemochromatosis when there is considerable iron overload?








Constant tiredness, weakness, lethargy
Abdominal pain
Joint pain (arthritis); this can affect any joint but
commonly affects the knuckle and first joint of the
first two fingers
Late onset diabetes
Cirrhosis of the liver (scarring of liver tissue that
damages liver function)
Bronzing of the skin, like a permanent tan
Loss of libido
Late onset diabetes
People with HH can have no symptoms for many years and some will never experience problems
What age do people develop hereditary haemochromatosis?
The build up of iron takes many years so the onset of HH is normally between 30 and 60 years. Women tend to
develop HH later in life than men. The reason for this is that before the menopause, having periods
(menstruation) regularly removes blood, and therefore iron, from the body. So before the menopause woman do
not accumulate so much iron in their bodies as men do, unless they use contraceptives that stop the periods or
have early removal of the womb.
Is it possible to cure or prevent hereditary haemochromatosis?
An early diagnosis means that treatment can begin before an individual develops serious symptoms. For
individuals diagnosed after symptoms present, it is not possible to undo tissue damage (such as cirrhosis of the
liver) if that damage has already occurred. For this reason it is important that immediate family members of an
individual with HH are offered genetic testing to find out if they are at risk.
Some symptoms may improve after treatment begins and individuals may feel more energetic and happier.
Some individuals who are at risk of iron overload but have iron levels within the normal range choose to donate
blood. This can help by removing iron and makes sure their blood is put to good use.
What causes hereditary haemochromatosis?
HH is caused by changes in a gene known as HFE. These changes make the gene not work the way it is
supposed to.
We all have about 25,000 pairs of genes inside every cell of our body. Genes are the instructions that tell our
body how to grow and develop. We inherit one copy of each gene from our mother and the other copy from our
father. When we have children we pass on one copy of each of our genes and our partner provides the other.
Someone that has one gene change and their other gene is working properly, is a carrier of HH. Carriers are
healthy as they still have one copy working properly, and they are not at increased risk of developing iron
overload.
When someone has a change in both copies of their HFE gene then they are at risk of developing iron overload.
There are two common gene changes, known as C282Y and H63D.
These changes are common in the Northern European population, probably due to an evolutionary advantage in
times when food was scarce. About 1 in 8 people in this population will carry a C282Y gene change, and about
1 in 5 people will carry an H63D gene change.
What is the difference between C282Y and H63D?
Having two copies of the C282Y gene change:
People with two copies of the C282Y gene change are at risk developing HH. However, many individuals with
two of these changes will never develop iron overload. Yearly blood tests are recommended to monitor iron
levels.
Having one copy of C282Y and one copy of H63D:
People with one copy of C282Y and one copy of H63D have a smaller risk of developing HH and the degree of
iron overload tends to be less than for individuals with two copies of C282Y. It is recommended that iron levels
are monitored every 3 years.
It is not clear if having two copies of H63D increases the risk of HH therefore occasional checking for iron
overload is suggested.
How do you test for hereditary haemochromatosis?
There are two types of tests used to help determine if someone has Hereditary Haemochromatosis.
The first is a gene test. This is a blood test that checks if an individual has any gene changes and is at risk of
developing iron overload.
The check if an individual has iron overload, two other blood tests (called serum ferritin and total iron binding
capacity) check the amount of iron in the blood.
Should someone with haemochromatosis have a low iron diet?
It is advisable for people with HH to avoid taking in too much iron. They can do this by:
 not taking multivitamins containing iron or iron tablets
 avoiding or reducing foods which are rich in iron such as red meat and red wine
 avoiding foods fortified with iron, such as some breakfast cereals
Who in the family is at risk of hereditary haemochromatosis?
An individual with HH inherited each of their gene changes from their parents. This means that parents of an
individual with HH will be carriers of HH. Occasionally the parents of someone with HH can have two altered
copies of the gene so they are at risk of developing HH themselves.
When both parents are carriers, each of their children has a 1 in 4 chance of having two altered copies of the
gene. This means that brothers and sisters of an individual with HH have a 1 in 4 (25%) chance of being at high
risk of HH themselves.
In fact every time two carriers have a child there will be a:
 1 in 4 (25%) chance neither parent will pass on altered gene so the child will not be a carrier of HH
 1 in 2 (50%) chance one parent will pass on the gene change and the other will pass the unaltered
gene so the child will be a carrier of HH
 1 in 4 (25%) chance both parents will pass on the gene change so the child will have a predisposition to
iron overload
Should my children be tested?
If you are a carrier or have two gene changes then there is a chance you could have passed down a changed
gene to your children. However, you children are at risk of being affected only if your partner also has a gene
change. Therefore, we recommend testing your partner first to know the risks to your children. If your partner
does not carry any gene changes then your children are unlikely to be affected. If your partner does carry one or
two gene changes then your children can have the test as adults. Testing is offered only when the child
becomes an adult as there is no medical reason to be tested in childhood.
If your partner or adult children would like to find out if they have any gene changes for HH then they should ask
their GP about being tested. They should ask for: a genetic test for HH and a blood test for ferritin and full iron
studies.
Where can I find more information?
The Haemochromatosis Society (www.haemochromatosis.org.uk)
If you have any questions you can contact your Community Genetics Team on 0141 354 9200
Text adapted with kind permission from Clinical Genetics Unit, Great Ormond St Hospital, Great Ormond St, London WC1N 3JH