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WGS for diagnosis of rare diseases in the health system

Rare diseases are a heterogeneous group of disorders that affect 65 people for every 100,000 individuals. Even with the low prevalence in the general population, they are important for public health. Together, worldwide there are about 6,000 to 8,000 different types of rare diseases, affecting 3.2 to 13.2 million people in Brazil. Generally these diseases are chronic, degenerative and can lead to death; about 30% of affected patients die before 5 years of age. However, when there is an adequate treatment, it is able to prevent the worsening and evolution of rare diseases.

Due to the complexity, the care of patients with rare diseases is considered a global challenge. The treatments and scientific information are scarce, with great demand for specialized professionals. Currently, the diagnosis of these diseases, even those with known etiology, is restricted, and may require more than 20 medical appointments over several years to determine the cause of the disease.

The development of the Whole Genome Sequencing or WGS and the integration in health systems carried out in some countries allowed the advance in the diagnosis of many of the diseases. Although rare variants in 1,500 genes have already been discovered, many genetic variants that cause disease are still unknown.

In the article by Turro et. al. (2020), published by the journal Nature, the WGS technique was performed on 13,037 patients, in 57 hospitals in England’s national health service and 26 hospitals in other countries. Of these patients, 9,802 had some of the rare diseases. 95 Mendelian associations between genes and rare diseases have been identified, 11 of which have been discovered since 2015 and 4 new non-coding variants that cause disease. Therefore, this study demonstrated the relevance of using WGS for the diagnosis and etiological discoveries of rare diseases in health centers, and the importance of including this service in the health system.

In Brazil, the Ministry of Health has 17 qualified and specialized health establishments for the care of patients with rare diseases, but the WGS technique is not established for diagnosis. Therefore, there are still many barriers to be overcome when it comes to rare diseases, since early diagnosis to appropriate treatment and counseling for rare disease. These are the ones that establish the patient’s quality life and everyone around him, especially family members.

References:

[1] FERREIRA, Carlos R. The burden of rare diseases. American Journal of Medical Genetics Part A, v. 179, n. 6, p. 885-892, 2019.

[2] MINISTRY OF HEALTH. Rare diseases: what they are, causes, treatment, diagnosis and prevention. Available at: <http://www.saude.gov.br/saude-de-a-z/doencas-raras>. Accessed on: July 3, 2020.

[3] TURRO, Ernest et al. Whole-genome sequencing of patients with rare diseases in a national health system. Nature, v. 583, n. 7814, p. 96-102, 2020.

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