Rare diseases are those that affect few people, that is, a very limited number of the population. In fact, a specific disease is considered rare when its prevalence is less than five people per 10,000 inhabitants. There are approximately seven thousand rare diseases cataloged as such.
In Spain, it is estimated that some three million people suffer from one of these diseases, and two out of three manifest themselves before they are two years old . Of every 100 children who die in Spain in their first year of life, it is estimated that 35 do so due to a rare disease.
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More than half are diagnosed in children
Unfortunately, the little ones also suffer from this type of disease, causing confusion and anguish in parents . As many of them are unknown, the diagnosis is very complex and can be delayed for years, and for some there is no treatment.
In 50 percent of cases, rare diseases appear in the pediatric age , given the high frequency of diseases of genetic origin and congenital anomalies that are included within the denomination ‘rare disease’.
80 percent of rare diseases are genetic , while the remaining 20 percent are due to environmental factors, infectious agents or causes that are still unknown.
However, the prevalence is higher in adults than in children, due to the excessive mortality of some serious childhood diseases. Rare diseases are responsible for 35% of deaths before one year of life, 10% between 1 and 5 years and 12% between 5 and 15 years.
“In many cases they do not have a specific and/or effective treatment, and in addition they tend to be diseases that generate serious and disabling consequences for patients, with high rates of morbidity and mortality. Likewise, they usually have a genetic origin and the most frequent are those that affect the nervous system”, explains Dr. Jorge Matias-Guiu Guía, Coordinator of the Neurogenetics and Rare Diseases Study Group of the Spanish Society of Neurology (SEN).
21 rare diseases that affect children
We list some of the most common rare diseases that children can present and have a genetic component:
1. Cystic Fibrosis
Cystic Fibrosis is the most common genetic disorder among Caucasian children . It is a disease characterized by the production of sweat with a high salt content and mucous secretions with an abnormal viscosity. It usually appears during early childhood or, more rarely, at birth.
Any internal organ can be affected, although the main manifestations affect the respiratory system (chronic bronchitis), the pancreas (pancreatic insufficiency, adolescent diabetes and occasionally pancreatitis) and, more rarely, the intestine (stercoral obstruction) or the liver (cirrhosis). , harmed by the buildup of sticky mucus, which tends to stick to these areas.
2. Rett Syndrome
Rett Syndrome is the consequence of mutations in the X chromosome and for this reason it always manifests itself in girls , although in atypical cases it can occur in boys. It is not so obvious at birth, but tends to manifest itself during the second year of life.
It is characterized by a significant global delay in development that affects the nervous system, the symptoms of which are a delay in motor coordination and language. Apraxia (inability to perform motor functions) interferes with all body movements, including gaze and speech.
As the syndrome progresses, involuntary movements of the hands, characteristic of people with this syndrome, are observed.
3. Spinal muscular atrophy (SMA)
Spinal muscular atrophy (SMA) is one of the most common rare diseases, whose early detection in the first months of life is key to starting treatment as soon as possible, slowing down the disease and improving the child’s quality of life. Buying time is essential in a disease that progresses very quickly, so it is very important to pay attention to its early symptoms.
It affects approximately 1 in 10,000 live births and is caused by the absence or abnormality of a gene, specifically SMN1. This defect causes the rapid and irreversible loss of a type of neuron (motoneurons) in children who suffer from it, which affects such relevant functions as breathing, swallowing and movement . Depending above all on its severity, we can talk about various types of AME.
4. Moebius syndrome
This disease, also known as Moebius Sequence, occurs when two cranial nerves do not fully develop. These nerves are responsible for blinking, lateral movement of the eyes and facial expressions thus causing paralysis of the face. This causes drooling, speech difficulties and pronunciation problems.
People with Moebius syndrome cannot smile or frown , and cannot often move their eyes from side to side. Some children go undetected for months and sometimes even years after birth.
5. Prader Willi Syndrome
Prader Willi syndrome is a genetic disease characterized by obesity with hypotonia (decreased muscle tone) and hypogenitalism (insufficient development of sexual characteristics), acromicria (atrophy or excessive smallness of the extremities) and mental retardation.
Hypotonia is severe in the neonatal period , it leads to respiratory infections and feeding problems, while obesity begins between 6 months and 6 years.
6. Phelan-McDermid syndrome
It is a genetic disorder that involves a mutation of chromosome 22 due to an alteration of the SHANK3 gene. 80 percent of people with this disease have an autism spectrum disorder. In Spain, there are 160 diagnosed cases but it is estimated that there are about 4,000 cases.
Affected individuals suffer from delayed neurocognitive development in multiple areas, especially in their ability to speak and communicate . To this is added the autism suffered by the majority, in addition to hypotonia, renal and cardiovascular problems, and lack of motor skills.
7. Aase Syndrome
Aase syndrome or Aase-Smith syndrome is a rare, sometimes inherited disease caused by insufficient bone marrow development .
It is characterized by pronounced anemia, congenital craniofacial malformations and limb deformities.
Babies with this disease have problems with breastfeeding, speech delay, motor delay, scoliosis, hydrocephalus, cleft palate, strabismus, and cardiac malformations.
8. Hutchinson-Gilford Progeria Syndrome
It is a genetic disease that causes premature aging in children. The little ones who suffer from it are usually born totally healthy and the disease manifests itself after a few months.
It is also known as “Benjamin Button disease” , for the film ‘The Curious Case of Benjamin Button’ , starring Brad Pitt and Cate Blanchet in which the protagonist is born in the body of an old man and rejuvenates over the years until become a baby.
9. Tourette Syndrome
It is traditionally known as “Tics disorder” and affects one in every hundred people. Almost 90 percent of people with tics have other associated disorders, such as: Attention Deficit Disorder, Obsessive Compulsive Disorder, Phobias, social hypersensitivity, depression or Anxiety.
Generally, the first symptoms usually consist of tics in the face (normally blinking) with time, other motor tics appear (such as movements of the head, neck, kicks, etc.) and to this is added at least some phonic tic (throat clearing , strange sounds, words, etc.)
The variety of tics or tic-like symptoms is enormous . The complexity of some symptoms often confuses family members, friends, teachers, and employers, who may find it hard to believe that the actions or words spoken are involuntary.
10. Butterfly Skin
It is also known as hereditary epidermolysis bullosa (EA), epidermolysis bullosa (EB) and they are a group of genetic diseases that have in common the existence of extreme fragility of the skin and mucous membranes, causing blisters in the vast majority.
In Spain almost 500 people live with this rare genetic disease that is detected as soon as they are born. Its diagnosis is frequently devastating not only for those affected, but also for their families, since it is a degenerative disease that has no cure today , and people who suffer from it must always be bandaged.
Fortunately, its prevalence is low, being included in the group of “rare diseases” (those with a frequency of less than 1 case per 2,000 people). According to the latest data from DEBRA International, it is estimated that the incidence of the disease in all its types is 15-19 births
Hemophilia, a rare disease that affects children characterized by an alteration in blood coagulation caused by a genetic defect, which causes the absence or decrease of some of the coagulation factors. Depending on its degree, it has more or less serious consequences.
There are three types of Hemophilia: A and B (characterized by spontaneous or prolonged bleeding) and C (with moderate bleeding symptoms). They are all hereditary disorders and, in general, affect more men than women. Likewise, its diagnosis often occurs when affected children learn to walk, as explained by the Spanish Federation of Rare Diseases, although if one of the parents already has it, tests can be done even before the baby is born.
12. Duchenne disease
Duchenne muscular dystrophy (DMD) mainly affects males. It is a rare and fatal genetic disorder that causes progressive muscle weakness from early childhood and leads to premature death around the age of 20 due to heart and respiratory failure.
It is a progressive muscle disorder caused by a lack of the functional protein dystrophin. Dystrophin is critical to the structural stability of all muscles, including skeletal muscles, the diaphragm, and the heart. It affects 1 in 3,500 children in the world (around 20,000 new cases each year)
A preschooler with DMD may appear clumsy and may fall frequently . Before long, he has trouble climbing stairs, getting off the ground, or running. By school age, the child may walk on their toes or toes, exhibiting a somewhat rolling gait. His gait is unsteady and he waddles and can fall over easily. To try to keep his balance, he sticks out his belly and pushes his shoulders back.
He also has difficulty raising his arms. Almost all boys with DMD stop walking between the ages of 7 and 12. In the teenage years, activities that involve the arms, legs, or trunk require help or mechanical support.
13. Sanfilippo syndrome
It is a rare and devastating disease , known as childhood Alzheimer’s, which affects one in 50,000 births. The disease is usually diagnosed between two and six years of age .
It is an inherited disease caused by the absence or malfunction of one of the cell enzymes needed to break down and recycle complex materials that the body does not need.
Due to this genetic fault, the material that it should break down (heparan sulfate) accumulates in the cells with devastating consequences for the organism, causing mental deterioration, hyperactivity and self-destructive tendencies , leading to premature death during adolescence.
The disconcerting thing about Sanfilippo Syndrome is that its symptoms are not easily identifiable, therefore they can be confused with other disorders such as attention deficit disorder (ADD), due to hyperactivity and learning difficulties.
In general, in the first years the growth of the child is normal. There may be some signs such as slight hepatomegaly (pathological enlargement of the liver), caries, chronic rhinitis, repeated upper airway infections and chronic diarrhoea, but nothing too noticeable.
14. Dermatomiositis juvenil
We talked about this disease when we echoed the emotional letter from the father of a recently diagnosed three-year-old boy. It is a rare, serious and chronic disease of autoimmune nature and onset before the age of 16 . Its cause is unknown, although there is a tendency to think that the trigger could be a viral infection.
It is known as “the invisible disease” and is characterized by inflammation of the muscles (myositis), the skin, the blood vessels and sometimes some other organ of the body. It is a very rare disease that affects four children per million.
Symptoms can range from mild muscle weakness, such as difficulty getting out of chairs or turning in bed, to severe symptoms such as severe weakness or difficulty swallowing. Lesions, rashes or skin changes, from mild redness to severe ulcer formation, may also appear, mainly on the face and hands.
15. Leigh Syndrome
Leigh syndrome or subacute necrotizing encephalomyelopathy is a progressive neurological disease defined by the specific neuropathological characteristics associated with lesions of the brainstem and basal ganglia.
Its prevalence at birth is estimated at one in 36,000 babies . The onset of symptoms typically occurs before 12 months of age but, in rare cases, can occur during adolescence or even early adulthood.
The usual initial symptoms are the lack of acquisition of the stages of motor development, hypotonia with loss of head control, recurrent vomiting and movement disorders.
16. Ictiosis laminar
It is a rare dermatological disease known as “fish skin” that affects one in 250,000 births. In addition to severe pain and growth retardation, it endangers the child’s life.
The newborn is usually born wrapped in a collodion membrane that comes off between 10-14 days later. Its name comes from the Greek Ichtys (meaning fish) due to the resemblance between the skin of people suffering from the disease and the scales of a fish.
In Spain there are 300 people affected by lamellar ichthyosis , according to data from the Spanish Ichthyosis Association (ASIC). Despite its low prevalence, this disease is important to give it visibility and dissemination, since the families and children who suffer from it need everyone’s support and understanding.
17. Angelman Syndrome
There is a case between 15,000 and 20,000. It is also known as Happy Puppets disorder (happy puppet) due to some symptoms such as excessive laughter and happiness, rigid speech and spastic movements.
Before the age of three, it is very difficult to identify the syndrome. They are usually very active babies, with abnormal sleep cycles. But it is only after three years when it is possible to detect the problem. The lack of coordination of movements, hyperactivity, problems walking, speaking, difficulty communicating and differentiated facial features.
They may have an abnormally small head, an enlarged mouth and jaw, a protruding tongue, and facial muscle abnormalities. This causes trouble swallowing, speaking, and ongoing drooling.
Some may also have strabismus, hypopigmentation of the skin and eyes, and mental retardation.
Galactosemia (etymologically means ” galactose in the blood”) is a hereditary disease caused by an enzyme deficiency, which affects the metabolism of galactose. A baby with galactosemia could accumulate galactose derivatives in her body, which could damage her liver, brain, kidneys, and eyes.
In Western countries it affects approximately one in 50,000 newborns. It occurs when babies do not have enough of the enzyme called galactose-1-phosphate-uridyltransferase (GALT).
People with galactosemia are unable to completely break down the simple sugar galactose. Therefore people with galactosemia cannot tolerate any form of milk (human or animal) and babies must be given an alternative.
19. Fragile X Syndrome
Fragile X Syndrome (FXS) is the most common form of hereditary mental retardation and is one of the most frequent rare diseases.
The syndrome affects 1 in 4,000 men and 1 in 6,000 women. Facial features appear around three years of age and these vary depending on the sex of the baby. Males present, to a greater or lesser extent, a long face, large ears, prominent jaw and macroorchidism from puberty. Connective tissue abnormalities, recurrent otitis in childhood, and mitral valve prolapse in puberty may also occur. Neurological manifestations are equally multiple, such as mental retardation, autism and epileptic seizures.
In women, the prevalent clinic is not mental retardation, but they have language disorders, reading and writing disorders, attention deficit and emotional disorders.
20. Treacher Collins Syndrome
Treacher Collins -Franceschetti syndrome, also known as mandibulofacial dysostosis, affects two out of every hundred thousand births and is characterized by craniofacial malformations.
It is caused by the genetic mutation of chromosome 5 (Treacle) that affects the way in which the bones of the baby’s face develop in the womb. It affects men and women alike.
Children who suffer from it present a craniofacial malformation that involves facial anatomical alterations that affect hearing (deafness), sight (eye problems such as dryness and corneal ulcers), breathing (apnea) and food intake.
Most people with Treacher Collins Syndrome have normal development and intelligence.
21. Turner syndrome
Turner Syndrome is a genetic disease that only women have . It affects one in every 2,500 or 3,000 births and girls are the carriers of this anomaly, which consists of the total or partial loss of one of the X chromosomes.
One-third of girls with Turner syndrome are identified shortly after birth. Approximately another third will be identified in school age due to conspicuous short stature and the remaining third will be identified in adolescence or adulthood due to lack of pubertal development , lack of ovulation or infertility.
Among the most common symptoms we find short stature, lack of development of sexual characteristics, in babies lymphatic edema in the hands and feet is one of the alerts that should always be consulted with the pediatrician if they appear. They present other bodily manifestations such as a wide thorax, a deformed elbow (cubitus valgus), a short and wide neck, and very low hairline growth.