These rare diseases have some of the most unusual signs and symptoms in medicine. In fact, these strange illnesses are so uncommon that in many cases the symptoms may be misdiagnosed, and the causes are still unknown.
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10. Congenital Insensitivity to Pain
Frequency: 100 documented cases in the United States.
Description: An inability to feel pain. People with this illness may die young from injuries because they lack pain perception, and must be constantly supervised so they don’t injure themselves.
Cause: A mutation in a gene located in the neurons associated with the reception and transmission of pain stimulus. |
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9. Moebius Syndrome
Frequency: About 80 documented cases in Spain, 200 in the U.K., and about 300 each year in Europe.
Description: People born with Moebius Syndrome have undeveloped facial nerves that make them unable to make facial expressions. Along with being unable to smile, frown or control their blinking, they have difficulty swallowing, speaking and doing any activity that involves facial muscles.
Cause: Unknown. |
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8. True Hermaphroditism
Frequency: Around 500 documented cases in the world.
Description: Hermaphrodites have components of both sexes, including both testicular and ovarian tissue. They may have a feminine or masculine appearance, and their external genitals may have characteristics of both sexes.
Cause: When two zygotes that were going to be twins of different sexes become fused, it results in one individual that is, genetically, both a man and a woman. It is not know why the fusion of zygotes occurs. |
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7. Fibrodysplasia Ossificans Progressiva
Frequency: Between 200 and 300 documented cases around the world, although it’s thought that this condition is often undiagnosed. It is estimated that one case appears in every 2 million births.
Description: Injuries to connective tissues (muscles, ligaments, tendons) result in the formation of bone around the damaged site. Injuries may cause joints to become frozen in place, and eventually a second skeleton begins to form that restricts mobility. Surgery is not an option to remove the bone growth because the body would try to repair the area with more bone.
Cause: Unknown. |
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6. Ondine’s curse (Congenital Central Hypoventilation Syndrome)
Frequency: Between 200 and 300 cases exist around the world, but it’s estimated that one baby out of every 200,000 could have this disease.
Description: The mechanisms of involuntary breathing do not work properly. In the most serious cases, this means a person cannot sleep without assisted ventilation. In more mild forms, patients can sleep through the night, but the lack of oxygen makes sleep difficult.
Cause: The main cause is one or several mutations of PHOX2B gene with autosomal dominant inheritance. |
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5. Proteus Syndrome
Frequency: About 200 documented cases in the world.
Description: This is the syndrome that afflicted Joseph Merrick, the “Elephant Man.” It causes malformations, irregular growth of bones, hyperpigmentation and partial gigantism of your limbs.
Cause: Unknown. |
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4. Progeria (Hutchinson-Gilford Syndrome)
Frequency: Around 100 documented cases, although it often is not diagnosed.
Description: People with progeria age very quickly. They appear normal at birth, but then quickly acquire wrinkles, lose their hair and suffer damage to their arteries that results in death during adolescence.
Cause: Most of the cases of progeria are caused by mutations of autosomal dominant inheritance in the LMNA gene. This gene participates in the maintenance of nuclear stability and the organization of chromatin. It may also help to regulate genetic expression, synthesis and DNA repair. |
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3. True Human Tail (Vestigial Tail)
Frequency: Around 100 documented cases in the world.
Description: The presence of a vestigial tail in the final zone of the sacral bone. This tail is made of connective tissue, muscles, blood vessels, nerves, skin, vertebrae and cartilage.
Cause: Unknown, possibly caused by a genetic mutation. |
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2. Parasite Twin (Fetus in Fetus)
Frequency: Around 100 documented cases in the world.
Description: Two twins do not separate fully, and while one twin may be healthy, the other degenerates and remains inside the other. If the host twin survives, he or she may show extra organs or swelling in the area where the parasitic fetus resides (this is typically in the abdominal region, but may also occur in the skull, *** or sacral region).
Cause: This is an exaggerated case of Siamese twins, but the cause remains unknown. |
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1. Human Werewolf Syndrome (Congenital Hypertrichosis Lanuginosa)
Frequency: About 40-50 documented cases in the world.
Description: People who suffer from it are completely covered in lanugo hair except on the palms of their feet and hands. Lanugo is a thin, off-white hair that appears on newborns but typically disappears during the first few weeks of life. The maximum hair length that has been documented is about 25 centimeters.
Cause: Unknown. |