Myelodysplasia, also known as Myelodysplastic Syndrome (MDS), includes a collection of diseases (sometimes referred to as a group of cancers) which affect the growth and development of healthy blood cells in your bone marrow.¹

In the past myelodysplasia was called “pre-leukaemia” as in some cases the disease transforms to Acute Myeloid Leukamia (AML), although this does not always occur.

The malignant cell in myelodysplasia is a myeloid stem cell. Such bone marrow stem cells are cells that can develop into any type of blood cell (i.e. they are responsible for making red blood cells, white blood cells and platelets). ²

In the vast majority of cases it is not known why someone develops myelodysplasia, with the exact cause of the disorder not fully understood.^1,2 However, gene mutations (abnormal change in the DNA sequence) that occur during a person’s lifespan play a role in the development of the disease.

Other factors that are thought to increase the risk of MDS developing include: ^1,2

• exposure to certain chemicals such as benzenes and petroleum-based products
• having had chemotherapy or radiation treatment
• people with certain congenital conditions such as Down’s Syndrome or Fanconi anaemia have an increased risk.

Myelodysplasia is generally suspected based on abnormal blood tests and confirmed by a bone marrow examination.

The World Health Organisation defines certain sub-types of MDS based on the following information from blood tests and bone marrow examination ⁵

• Percentage of blast cells in the bone marrow. Blast cells are immature cells which are usually only found in the bone marrow but can be found in the blood with diseases such as MDS or leukaemia
• Chromosomal changes (Cytogenetics). A test performed on bone marrow cells collected at a bone marrow examination
• Ring sideroblasts. Cells seen on a bone marrow examination
• Dysplasia. Blood cells that show abnormalities under the microscope
• Number of cytopenias (low blood cell counts). This information is gained from blood tests

The common sub-types of myelodysplasia include:

• Refractory Anaemia (RA) – This type of MDS affects red blood cells¹
• Refractory anaemia with ringed sideroblasts (RARS) – similar to RA, except the red blood cells contain iron ring deposits around the nucleus of the cell¹
• Refractory cytopenia with multilineage dysphasia (RCMD) – two or more affected types of blood cells, with less than 5% of blast cells found in the bone marrow¹
• Refractory cytopenia with multilineage dysphasia and ringed sideroblasts (RCMDRS) – Similar to RCMD, except the red blood cells contain iron ring deposits around the nucleus of the cell¹
• MDS with del(5q) chromosome – affects the red bloods cells, causing anaemia, however it is associated with good outcomes¹
• MDS with excess blasts (MDS-EB, also called RAEB ie. Refractory anaemia with excess blasts) – there are one or more affected blood cells
  • Type 1 = Bone marrow consists of up to 9% of blast cells, with less than 5% found in the blood
  • Type 2 = Bone marrow and circulating blood consists of up to 19% blast cells
• Mixed Myelodysplastic/myeloproliferative neoplasms (MDS/MPN)– a group of blood diseases that aren’t specific to any of the above MDS types. MDS/MPN have both too few and too many blood cells produced in the bone marrow¹

In the early stages of the disease there are often few, if any symptoms and the diagnosis is suspected due to abnormal blood tests alone.¹   However, as the disease progresses people can experience the following symptoms depending on the type and severity of MDS. ¹

Symptoms related to white blood cell abnormalities include: ²

Symptoms related to red blood cell abnormalities include:

Symptoms related to platelet abnormalities include: ^1,2

Treatment depends on the sub-type of MDS you have, age as well as your medical history and preferences for treatment. Some treatment options for MDS can include:

• Chemotherapy – uses specific drugs to target and destroy the blast cells found in your bone marrow⁶
• Stem cell transplant – involves transplanting stem cells from a healthy donor, however this option is usually only suitable for a small number of younger patients with MDS⁶
• Watch and wait – often this is an option early on in the disease, where patients have few symptoms. Regular check-ups and monitoring is recommended⁶
• Supportive therapy – these involve a series of treatment options (including transfusions) to help reduce symptoms such as treatments for low red and white blood cells and platelets ⁷
• Imunomodulatory drugs – uses specific drugs to help improve marrow function. Very effective in the 5q- sub type of MDS
• Clinical trials – can be a way to access novel therapies not yet licenced for routine use