12 Rarest Medical Conditions The World Has Ever Seen

It's mind-boggling how much luck goes into creating a healthy human being. 

With only a slight mutation of a very small strand of genetic information, your body can work in a totally different way. Sometimes you can judge how your body and mind will end up based on what you observe from the rest of your family, but it's also possible for a condition to quietly pass through your family genes before some slight change in your DNA brought it to the forefront.

Most people won't have even heard of some of the conditions on this list, but the rare few who have them live with their extreme effects every day.

It can definitely be said that these 12 rare medical realities will make life interesting — but not in a way that most of us would want.

1. Cotard's Syndrome

In the most extreme cases, this sad mental disorder leads its sufferers to believe that they are dead.

Those afflicted with this variation of the disease will often feel compelled to visit cemeteries and morgues for the purpose of joining their "fellow" dead people. 

Cotard's syndrome is often linked with intense feelings of depression and paranoia, as being alive will feel unnatural to those afflicted with it.

A man named Per "Dead" Ohlin of the black metal band Mayhem was suspected to suffer from Cotard's syndrome, as he often expressed his belief that he was already dead and was reported to keep a dead crow around so he could sing with "death in his nostrils."

2. Nystagmus

Sometimes called, "dancing eyes," this brain disorder impairs the functions of the labyrinth, a part of the inner ear that helps control eye movements. As a result, those afflicted with nystagmus will experience rapid, uncontrollable eye movements. 

Nystagmus is often congenital, or present at birth, but it can also develop from the use of an anti-seizure medication called Phenytoin, as well as from severe head injuries, strokes, and inner ear disorders.

3. Oligodactyly

Those afflicted with this condition are born with less than five fingers on each hand. The remaining fingers can be perfectly functional, but vary in number depending on the severity of the condition. 

It's usually heredity, but can also be associated with other diseases like Roberts syndrome in cases where there's no family history of oligodactyly.

4. Polydactyly

As opposed to oligodactyly, this condition finds its sufferers born with extra fingers or toes. 1 in 1,000 babies are born with some degree of polydactyly, but it's rarer for the extra digits to be fully formed and functional.

Like oligodactyly, it's an inherited condition, but it usually only manifests in one member of a family.

5. Alien Hand Syndrome

Those who suffer from alien hand syndrome will find one of their arms moving independently of their commands, usually through involuntary grabbing.

This movement can be more complex, however, creating the impression that the arm has a mind of its own.

Alien hand syndrome usually develops following damage to the corpus collosum, or the bundle of fibers that connects the right and left hemisphere of the brain.

The culprit is often a brain tumor, but alien hand syndrome can also emerge in the wake of some surgical procedures used to treat epilepsy, as they may involve creating divisions in the corpus collosum.

6. Albinism

Albinism is characterized by a lack of activity from an enzyme called tyrosinase, which is responsible for the early production of melanin.

Without any melanin pigment, an afflicted person not only finds themselves with white hair and pale skin, but very light colored eyes.

Unfortunately, these light colored eyes will seriously impair the sufferer's vision because melanin is needed to streamline the conversion of light energy into nerve signals that allow people to see.

7. Cold Urticaria

This "allergy" to cold involves the development of a rash as a reaction to direct exposure to cold objects, particularly ice or cold water.

In extreme cases, immersing a sufferer in cold water results in a whole-body reaction that can induce low blood pressure, shock or even death.

Cold urticaria is heredity in some rare cases, but can also develop as a side effect of diseases like mononucleosis, chickenpox and viral hepatitis. 

8. Foreign Accent Syndrome

As a byproduct of a stroke or a traumatic brain injury, sometimes people will involuntarily speak in a foreign accent.They don't become any less intelligible, but the timing and intonation of their speech will become more characteristic of a foreign accent than their native one.

9. Epidermodysplasia Verruciformis

This heritable disease leaves the sufferer extremely susceptible to HPV, resulting in the rapid growth of skin tumors that resemble tree bark.

To make matters worse, the "bark" puts an afflicted person at an extremely high risk of skin cancer when they're exposed to direct sunlight. 

10. Hailey-Hailey Disease

This hereditary skin disease is the result of a mutation of the gene that regulates the integrity of outer skin cells.

When the skin meets with friction, these cells separate, causing red, scaly patches or blisters to appear.

After a few days, the afflicted skin will clear up entirely and leave no evidence that the outbreak occurred in the first place. 

11. Hypertrichosis

Commonly called "the werewolf syndrome," this condition is characterized by excessive hair growth. It's unknown what causes the disorder, but it seems to be genetic in origin.

Aside from potential embarrassment and emotional burdens, the excessive hair growth seems to be the sole symptom of the condition. 

12. Argyria

Argyria is most known for irreversibly turning the sufferer's skin blue, or blue-gray. Argyria comes as a direct result of silver poisoning, usually through the ingestion of colloidal silver.

Argyria doesn't seem to exhibit any other symptoms, but sufferers have reported adverse reactions to their discoloration from others.

Main image via flickr / Paul Zollo

Collage images via 1. tumblr / mermaidmagpie 2. tumblr / archiveoftheunknown