What is aplastic anemia and why are telomeres important?

Aplastic Anemia Awareness Day - exploring relation to telomeres

March 4 is Aplastic Anemia Awareness Day, and to mark the occasion we want to shed some light on this condition and how it can be related to telomeres.

What is aplastic anemia?

Aplastic anemia is a rare, and potentially serious blood disorder, that occurs when the bone marrow fails to produce enough healthy blood cells.

Aplastic anemia can be classed as hereditary or acquired. The hereditary form is often more severe, and commonly diagnosed in childhood. This can be caused by an inherited genetic abnormality. Acquired aplastic anemia can be caused by an autoimmune condition or by toxicity, and is often diagnosed later in life. There are an estimated 600-900 new cases of aplastic anemia diagnosed in the US each year.

First line and supportive treatment options for aplastic anemia include blood (product) transfusions and immunosuppressive therapy.

Stem cell transplants are also an available treatment for aplastic anemia. A donor provides healthy stem cells that can travel to the recipient’s bone marrow and produce fully-functioning blood cells. For children with severe aplastic anemia, a transplant from an HLA matched sibling donor can be considered the first-choice treatment.

Telomeres and aplastic anemia

Telomeres act as a protective cap on the end of our chromosomes. They shorten as we age, however, in some individuals they are prematurely very short. Critically short telomeres can be a factor to be considered in diagnosis and treatment planning for those with hereditary aplastic anemia.

Studies have shown that telomere lengths in patients with aplastic anemia can vary. Nevertheless, when compared to healthy individuals a higher percentage of people with aplastic anemia have shorter telomeres.

It is known that patients with dyskeratosis congenita, an inherited bone marrow failure syndrome, have critically short telomeres. Some people with aplastic anemia will have an inherited mutation in a telomere biology gene, affecting telomere length. These individuals would be considered as having aplastic anemia as part of the telomere biology disorder spectrum, although would not necessarily be diagnosed with dyskeratosis congenita (this would depend on their other symptoms and family history).

Learn more about dyskeratosis congenita in this dedicated blog.

How telomere length results can impact clinical care for aplastic anemia

Telomere length can provide information for those undergoing immunosuppressive therapy, a common first line treatment. One clinical study found that lymphocyte telomere length measured at diagnosis could be useful in predicting the response to immunosuppressive therapy in children with aplastic anemia.

One of the key treatments for aplastic anemia is a stem cell transplant. It is important that the cells being donated are those most likely to be successful and telomere length can be an important factor in determining this. In the case of a related donor, it is essential to confirm that they are healthy and not similarly affected by a potentially heritable disease. In the case of an unrelated donor, studies have shown an age-independent association between longer donor telomere length and improved survival after stem cell transplant in severe aplastic anemia.

For a more in-depth exploration of stem cell transplants and telomere length have a read of this blog.

If you want to find out more about the conditions that telomere length testing can be useful for, take a look at this section of our website.

For more information or support, take a look at the Aplastic Anemia and MDS International Foundation website.

Sources
Sakaguchi, H. et al. Peripheral blood lymphocyte telomere length as a predictor of response to immunosuppressive therapy in childhood aplastic anemia. Haematologica. Aug 2014. 99 (8) 1312-1316. DOI: 10.3324/haematol.2013.091165.
Shahinaz, G,M. et al. Association between donor leukocyte telomere length and survival after unrelated allogeneic hematopoietic cell transplantation for severe aplastic anemia. JAMA. vol. 313,6 (2015): 594-602. doi:10.1001/jama.2015.7.
Townsley, D, M. et al. Danazol Treatment for Telomere Diseases. N Engl J Med. 2016; 374:1922-1931. doi: 10.1056/NEJMoa1515319.