You must have heard about the occurrence of some genetic mutations that may cause diseases such as cancer, but have you ever heard about rare hereditary diseases caused by the presence of genes that are passed down from parents to children and from generation to generation?
In the United States, a rare disease is defined as a condition that affects less than 200,000 people in the United States. The definition of a rare disease varies from one country to another. In European Union countries, a rare disease is defined as a disease that affects less than one person for every 2,000 people.
Here are some examples of rare genetic diseases
Rare genetic diseases: definition
There may be approximately 7,000 rare diseases around the world. There are many causes of rare diseases, but it is believed that the majority of these diseases have genetic causes as a result of a change or defect in genes or chromosomes. Here are some examples of rare hereditary diseases:
1. Congenital hypertrichosis lanuginosa
It is a rare genetic condition that causes excessive hair growth anywhere on the affected person''s body, and is also known as werewolf syndrome.
This syndrome may be confused with hirsutism, which causes excessive hair growth in women in areas where hair is abundant in men, such as the chin.
2. Xeroderma pigmentosum
It is known as a rare skin disorder in which the affected person''s skin is very sensitive to sunlight and suffers from premature skin aging, and the skin is also susceptible to skin cancer.
The disorder results from cellular hypersensitivity to ultraviolet radiation as a result of a defect in the DNA repair system.
Also called DeSanctis-Cacchione syndrome.
3. Porphyria
Porphyria refers to a group of disorders resulting from the accumulation of natural chemicals that produce porphyrin in the body, a substance necessary for the function of hemoglobin.
There are two types of it: acute porphyria, which mainly affects the nervous system, and cutaneous porphyria, which mainly affects the skin.
4. Epidermodysplasia verruciformis
It is a hereditary skin disorder characterized by a chronic skin rash in the form of brown plaques, and is caused by a viral infection with a type of human papillomavirus (HPV).
5. Fibrodysplasia ossificans progressiva
It is a disorder in which the skeleton and connective tissue such as tendons are gradually replaced by bone. This can be called ossification, as this leads to the formation of bones outside the skeleton, which restricts the movement of the affected person.
6. Proteus syndrome
It is a condition characterized by excessive growth of bones, skin, and other tissues that is disproportionate to the rest of the body.
7. Progeria syndrome
It is a very rare genetic disorder that causes rapid aging in children (presbyopia). This begins during the first two years of a child’s life. A child with the syndrome is born normal, but symptoms begin to appear during the first year of life.
Rare genetic diseases: causes
The majority of rare genetic diseases are believed to be directly caused by genetic or chromosomal changes.
In some cases, these disease-causing changes are passed from generation to generation, and in other cases, these changes occur randomly in the first person in the family to be diagnosed.
There are many rare diseases that have multiple causes and are not limited to genetic causes.
Rare hereditary diseases: symptoms
Symptoms of genetic diseases may vary depending on the severity and type of infection, and may also differ from one person to another. Below are some of the symptoms that may appear in people with one of the previously mentioned diseases:
Presence of ear deformities.
Unusually shaped eyes, or eyes colored in different colours.
Unusual or different facial features from family members.
Brittle or sparse hair, or thick hair on the body.
A large or small tongue.
Deformed teeth, or the presence of extra or missing teeth.
Unusual length, either unusually short or tall.
Excessive excess skin.
Excessive sweating or decreased sweating.
It should be noted that some of the previously mentioned symptoms may appear commonly in people who do not suffer from any disorder. At least two characteristics must be present in order to be diagnosed with any genetic disease, and this is done by a specialist doctor.
