The most common of these conditions are the myeloproliferative neoplasms (MPN), a group of blood disorders, related to leukaemia, that affect around 3,300 people in the UK every year.
When people have MPN, blood cell production becomes over-active causing the blood to become thick.
The myelodysplastic syndromes (MDS) are another group of blood disorders that affect around 2,000 people in the UK. Usually people with MDS make far too many blood cells, but these are mostly defective and not able to do their jobs properly. In fact most of these cells are destroyed before even entering the blood stream meaning that people with MDS have far too few cells in their blood.
Aplastic anaemia is another rare blood disorder that results in not enough blood cells being produced. However, unlike MDS and MPN, this disorder does not result in the production of cancerous or abnormal blood cells, rather a lack of healthy blood cells.
Find out about the research we're funding to beat rare blood cancers.