Thu. Jun 30th, 2022
Rare diseases in children: eleven questions about them that you should

The last day of February marks World Rare Disease Day, a day to raise awareness of rare pathologies and awareness of situations of inequity and injustice experienced by affected families, many of whom make themselves heard this day.

Today we will talk about them and answer eleven questions to get to know rare diseases better .

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What are rare diseases?

A disease is considered rare when it affects a limited number of the total population, defined in Europe as less than 5 per 10,000 inhabitants . Patients and the associations that support them show that it is crucial to realize that “it can happen to anyone, at any stage of life. Moreover, it is not unusual to suffer from a rare disease.”

For a disease to be considered rare, the same criteria are not followed throughout the world. For example, in Europe a disease that affects one in 2,000 people is considered rare. In the United States, this is defined as a disorder or disease suffered by fewer than 200,000 people.

To date, between 6,000 and 7,000 rare diseases have been discovered and new diseases are regularly described.

How many rare diseases are there?

It is estimated that there are more than 6,000 different rare diseases , which affect patients in their physical capacities, mental abilities and in their sensory and behavioral qualities.

How many people are affected?

Between 3.5 and 5.9% of the world population , more or less, would be affected by these diseases, that is, more than 3 million Spaniards, 30 million Europeans, 25 million North Americans and 42 million in Latin America.

From what age can an RD be detected?

Symptoms may be present from birth, even in fetal life. But they can appear at any age, especially in the first two years of life (2 out of 3 rare diseases manifest before the age of two).

When you think about these diseases and look for them, they can be diagnosed, even in fetal life, although it is more difficult because the studies to be carried out in these periods are much more complex. On the other hand, it is true that, sometimes, the doctor knows that he is seeing a patient with RD (because there are similar undiagnosed family cases, or because there is a test that suggests it).

What is the origin and characteristics of rare diseases?

While almost all genetic diseases are rare diseases, not all rare diseases are genetic diseases . For example, there are very rare infectious diseases, as well as autoimmune diseases and rare cancers. To date, the cause of many of these diseases remains unknown.

Rare diseases are serious and usually chronic and progressive diseases. In most rare diseases, signs can be observed from birth or childhood, as is the case with spinal muscular atrophy , neurofibromatosis, osteogenesis imperfecta, chondrodysplasia or Rett syndrome. However, more than 50% of rare diseases appear during adulthood, such as Huntington’s disease, Crohn’s disease, Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, Kaposi’s sarcoma or cancer of thyroid.

Why is your diagnosis so delayed?

A patient with a rare disease waits an average of 4 years to obtain a diagnosis, in 20% of cases it takes 10 or more years to achieve the proper diagnosis.

Only about 250 rare diseases have been assigned a code in the International Classification of Diseases (ICD) of the World Health Organization, which makes it even more difficult to address them. Sometimes, they are little-known diseases, but other times they are known, but due to their infrequency, in clinical practice they are not taken into account as the first diagnosis. As a consequence, if the disease is severe and rapidly evolving without treatment, it can cause the death of a newborn, or the appearance of important sequelae.

Thanks to the neonatal screening test , cases are being diagnosed that could go undiagnosed for years or even throughout the patient’s life.

What symptoms can make parents suspect that their child has an RD?

In general, they should be considered when the symptoms or an association of symptoms are not typical of any other disease or there is an unexplained association of symptoms. In childhood, it should be noted that many inborn errors of metabolism present with digestive and neurological symptoms, either chronically or in acute phases, for which a doctor is consulted.

Two out of three rare diseases manifest before two years of life.

What are the main problems faced by families of children with a rare disease?

Frustration, anguish, loneliness and a feeling of isolation are very frequent. But socioeconomic problems are also added, and given the chronicity of the disease and the unmet needs, such as: rehabilitation, physiotherapy, special orthopedic measures, special education, speech therapy, etc…

If medical procedures are diversified and a large number of consultations are needed, the repercussions on work are very serious. They require not only medical attention, but also psychological and social support, and often nutritional measures. The latter are absolutely essential in many inborn errors of metabolism.

Who should parents of children with Rare Diseases turn to?

They should consult with their pediatricians and they will refer suspected children to specialized centers, depending on the symptoms they have. Generally, researchers and reference centers with experts in RD are used, but an etiological diagnosis may still not be reached.

What are the Rare Diseases that most affect children?

In childhood, the most frequent genetic pathologies are thalassemias , which are the most frequent hereditary diseases in the world with around 250 million people affected. In Spain, they affect between 0.2 and 2% of the population, but there are only around a hundred diagnosed cases of thalassemia major.

Cystic fibrosis is also considered frequent, for which a prevalence between 1/8,000 and 1 in 10,000 individuals had been estimated in Europe. However, neonatal screening studies in Spain have shown a prevalence of 1 per 3449 newborns, a figure higher than those reported for RD.

Within the family of congenital myopathies, the more severe Duchenne disease affects 1 in 3300 male births and the rarer Becker disease affects 1 in 18,000 to 31,000 male births.

What are the main novelties in RD research?

In recent years, many advances are being made, emphasis is being placed on these diseases, seeking means to address them. Work is being done in many fields simultaneously: medical, social, research and the development of new treatments. Thanks to improvements in laboratory techniques and better knowledge of each disease, the number of diagnoses has increased and the development of new techniques, including mass spectrometry and high-throughput platforms for mutation analysis, has made it possible that more than 50 different genetic diseases can be detected in a single paper blood sample from the newborn.

With scientific advances, progress is being made in the knowledge of diseases, with the aim of finding more effective treatments, which although they are not curative for certain diseases, they do improve the quality of life of those affected.