Myelodysplasia affects the development of healthy blood cells in bone marrow.

Last modified: August 14, 2019

What is myelodysplasia?What is myelodysplasia?

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.

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).

Risk factors for myelodysplasiaRisk factors

In the vast majority of cases it is not known why someone develops myelodysplasia, with the exact cause of the disorder not fully understood. 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:

  • 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

Diagnosis of myelodysplasiaDiagnosis

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

Sub-typing of myelodysplasiaSub-typing

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

  • 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

Types of myelodysplasiaTypes

The common types of myelodysplasia include:

Refractory Anaemia (RA)

This type of MDS affects red blood cells.

Refractory anaemia with ringed sideroblasts (RARS)

This type of MDS is similar to RA, except the red blood cells contain iron ring deposits around the nucleus of the cell.

Refractory cytopenia with multilineage dysphasia (RCMD)

This involves two or more affected types of blood cells, with less than 5% of blast cells found in the bone marrow.

Refractory cytopenia with multilineage dysphasia and ringed sideroblasts (RCMDRS)

This type of MDS is similar to RCMD, except the red blood cells contain iron ring deposits around the nucleus of the cell.

MDS with del(5q) chromosome

This type of MDS affects the red bloods cells causing anaemia, however it is associated with good outcomes.

MDS with excess blasts

This type of MDS involves one or more affected blood cells. It is known as MDS-EB and RAEB (i.e. refractory anaemia with excess blasts)

  • 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)

This is 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 marrow.

Signs and symptoms of myelodysplasiaSigns and symptoms

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. However, as the disease progresses people can experience the following symptoms depending on the type and severity of MDS.

Symptoms related to white blood cell abnormalities include:

  • Increased susceptibility to infections, particularly chest infections. Other common infections include sinus, urinary tract and skin infections

Symptoms related to red blood cell abnormalities include:

  • Chronic fatigue and a feeling of weakness

  • Shortness of breath without exertion

  • Pale skin

Symptoms related to platelet abnormalities include:

  • Increased frequency of bruising and bleeding, especially from the gums and nose

Treatment for myelodysplasiaTreatment

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 marrow
  • 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 MDS
  • Watch and wait – Often this is an option early on in the disease, where patients have few symptoms. Regular check-ups and monitoring is recommended
  • 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
  • Imunomodulatory drugs – Uses specific drugs to help improve marrow function. This is very effective in the 5q- sub type of MDS
  • Clinical trials – This can be a way to access novel therapies not yet licensed for routine use

Frequently asked questionsFAQs

How is MDS diagnosed?

The first step in diagnosing MDS involves having a full blood count (FBC), also called a complete blood count (CBC), where blood is taken from a vein in your arm and sent to the laboratory where your red blood cells, white blood cells and platelets are analysed.

For most people diagnosed with MDS, they often have low numbers of platelets as well as red blood cells (anaemia). White blood cells may also be abnormal, with the presence of leukemic blast cells.

If your blood test results indicate you may have MDS, then you will need to have a bone marrow biopsy, which involves having a sample of bone marrow removed (usually from your hip bone). Analysis of the stem cells in the bone marrow, as well as the results from your blood test will indicate the degree of your MDS.

How common is MDS?

MDS is not overly common, occurring in about 4 in every 100,000 people. However, the incidence does increase with age, with approximately 20-50 in every 100,000 people developing MDS over the age of 60.


For a full list of references, click here.
  1. What is MDS? (2019). Leukemia Foundation. Retrieved on 16th June 2019 from
  2. What is MDS? (n.d). MDS Foundation. Retrieved on 16th June 2019 from
  3. Tests for Myelodysplastic Syndromes. (2018). American Cancer Society. Retrieved on 18th June 2019 from
  4. How is MDS diagnosed? (2015). Leukemia Foundation. Retrieved on 18th June from
  5. Types of Myelodysplastic Syndromes. (2018).American Cancer Society. Retrieved on 18th June 2019 from
  6. MDS Treatment. (2015). Leukemia Foundation. Retrieved on 18th June 2019 from
  7. Supportive Therapy for Myelodysplastic Syndromes. (2018). American Cancer Society. Retrieved on 18th June 2019 from
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