In 1930, it was discovered that children with Down’s syndrome are at a greater risk of developing certain types of leukaemia. Today, it is known that children and adolescents with Down’s syndrome are between 10 to 30 times more likely to develop leukaemia than children without the condition. It is therefore particularly important that parents or carers of children with Down’s syndrome are aware of the signs and symptoms of leukaemia.
What is Down’s syndrome?
Down’s syndrome is a very common genetic disorder that occurs in approximately one in every 700 births. It arises during the very first stages of development when abnormal cell division produces an extra copy of chromosome 21. This extra genetic material is responsible for certain developmental changes such as the distinctive physical characteristics and learning disabilities typically associated with Down’s syndrome.
Unfortunately, the genetic abnormalities that cause Down’s syndrome also increase the risk for a wide range of medical problems, such as congenital heart defects, gastrointestinal problems, hearing problems, and leukaemia.
Prevalence of leukaemia in Down’s syndrome
Children with Down’s syndrome are at an increased risk of developing any type of acute leukaemia. In particular, they are 150 times more likely to develop acute myeloid leukaemia (AML) and are at a 33 times greater risk of developing acute lymphoblastic leukaemia (ALL).
Around 10% of all newborns with Down’s syndrome are born with a unique “pre-leukaemia” condition known as transient leukaemia (TL). In most cases, TL will not result in symptoms and it will resolve spontaneously without any treatment. However, 1 out of 5 patients with TL will go on to develop AML, also known as myeloid leukaemia of Down’s syndrome (ML-DS).
Treatment of leukaemia in children with Down’s syndrome
Interestingly, the cure rates for leukaemia patients with Down’s syndrome are exceptionally high when compared to the general population.
The cure rate for childhood AML in general is already very high (around 75%), but Down’s syndrome children with a specific subtype of AML called acute megakaryocytic leukaemia (AMKL) have an overall survival rate of around 80%-100%, compared to only 35% in non-Down’s syndrome children. It is thought that the same genetic mutation that leads to leukaemia in these children with Down’s syndrome also helps them respond better to a certain type of chemotherapy.
On the other hand, it has been found that the cure rate of ALL in children with Down’s syndrome is slightly lower than what is expected in the general population (60-70% compared to 75-85%). This is perhaps partly down to the fact that children with Down’s syndrome are more prone to infections and are more likely to suffer from toxic side effects of chemotherapy.
Screening for leukaemia in children with Down’s syndrome
In June last year, new guidelines for doctors were published by The British Society of Haematology (BSH) stating that all children with Down’s syndrome should receive a full blood test within three days of being born to establish their risk of developing AML.
If the blood test displays high levels of abnormal cells in the blood stream, or if the child is presenting with physical symptoms of leukaemia (such as rashes, enlarged spleen or liver problems), the child should be given a new genetic test that looks for mutations in a gene called “GATA1”. Mutations in GATA1 are nearly always found in babies with transient leukaemia (TL).
This genetic test enables doctors to quickly establish which children with Down’s syndrome are at risk of developing ML-DS so that they can be closely monitored and quickly treated if needed. Although transient leukaemia is normally harmless, occasionally these patients will require low-dose chemotherapy to prevent them from developing potentially fatal liver failure.
The idea with this new screening test is that children found to have TL who do not present with serious symptoms should be carefully monitored for at least four years to make sure that the condition does not progress into leukaemia.
Can you spot the signs and symptoms of leukaemia?
This new screening test marks a huge advancement in the early diagnosis of leukaemia in patients with Down’s syndrome. However, even if the screening test comes back as negative, this doesn’t mean your child can’t develop leukaemia. The test only detects one form of acute leukaemia called AML and, since children with Down’s syndrome are at an increased risk of developing all forms of acute leukaemia, it is still hugely important for parents to keep an eye out for the physical signs and symptoms of leukaemia, so that they can spot leukaemia early.
You should contact your child’s doctor if you notice clusters of the following symptoms:
- Extreme tiredness
- Leg pain/limping
- Loss of appetite
- Feeling full or discomfort in the tummy (abdomen)
- Shortness of breath
- Unexplained bruising and bleeding
- A rash of purple spots (petechiae)
- Bleeding gums
Find out more about spotting leukaemia here.