Is Myelofibrosis A Rare Disease?

The rare disease is that disease which affects a smaller number of people. The definition of rare disease is different in different countries and it qualifies on the basis of population. It is possible that the rare disease in one country may not be a rare disease in another country. Special grants are provided by the Government to companies who develop drugs for rare diseases.

Is Myelofibrosis A Rare Disease?

Myelofibrosis is the condition in which the spongy bone marrow tissue becomes fibrous resulting in the reduced production of various blood cells. Myelofibrosis is a rare disease as it conforms to the criteria of the rare disease in many countries. Both primary myelofibrosis and secondary myelofibrosis are considered to be a rare disease.

Secondary myelofibrosis is considered as rare because the reason for secondary myelofibrosis i.e. polycythemia vera and essential thrombocythemia are themselves are rare conditions. Almost 15% of the patients suffering from polycythemia Vera develops myelofibrosis while only a few patients having essential thrombocythemia progresses to myelofibrosis. Myelofibrosis in the US has the prevalence of fewer than 200,000 patients and the incidence of the disease is approximately 3 patients per 100,000 populations. ⁽¹⁾

Myelofibrosis Prognosis

The prognosis of this rare disease is difficult to evaluate due to the different rate of progression and different symptoms experienced by the patient. Some people suffering from myelofibrosis do not have any characteristic symptoms and the disease is diagnosed through the routine blood test. Some patients have severe symptoms that affect their quality of life. These patients experience fatigue, depression, anxiety, weakness and recurring infections. Further, some patients respond favorably to treatment while disease in some patients fails to treat with the drugs. The risk of fatality is high in those patients whose disease progresses into acute myeloid leukemia, which is a highly fatal condition. The prognosis of the patient depends upon various factors. Age is one of the primary factors as young people are able to recover more quickly with the side effects of therapy and stem cell transplantation is more successful in young people. More the type of chromosomal aberration more is the risk of progression of the disease and poor the prognosis. Other factors affecting prognosis include dependency on blood transfusions, frequency of developing infections and level of platelets.⁽²⁾

Rare Disease

The rare disease is the disease which affects a small population at a given point in time. Thus, not a very high number of people are affected by these diseases. The rare disease is also known as an orphan disease in some jurisdictions. Due to a smaller number of patients available for treatment, the government provides various subsidies for the companies doing research on drugs for these diseases. The drugs for the orphan disease are known as orphan drugs. Most of the rare diseases are genetic diseases with ribose 5-phosphate isomerase deficiency is the rarest disease with only 3 patients diagnosed in the last three decades. The legal definition to qualify for a rare disease differs in different countries. In the USA, the disease which is present in less than 200,000 people is termed as a rare disease while in Japan; the disease which affects less than 50,000 people is a rare disease. European Commission defines the rare disease in term of low prevalence disease. Low prevalence is defined as the disease which affects 1 in 2000 people. Prevalence is generally used over incidence when defining the rare disease. The disease may be rare or common depending upon the area which is affected by the disease. For instance, cystic fibrosis is a rare disease in India while it is a common disease in the European region. Almost 80% of a rare disease has genetics involved. ⁽³⁾

Conclusion

Both Primary and secondary myelofibrosis are chronic and rare blood disorders. The disease is less prevalent in the US and Europe. In the USA, the people affected by this disease are less than 200,000. Prevalence of a disease is the criteria used for qualifying a rare disease.

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Is Myelofibrosis A Rare Disease?