In our world, disease and illness are becoming increasingly common. However, there are some conditions that are so rare, they are almost unheard of. These rare diseases and disorders affect a small number of people, and can often be difficult to diagnose.

Here are ten of the rarest diseases and disorders in the world.

Fibrodysplasia Ossificans Progressiva (FOP)

Fibrodysplasia Ossificans Progressiva (FOP) is an incredibly rare genetic disorder that affects just 1 in 2 million people worldwide. It causes the body’s muscles, tendons, and ligaments to slowly turn to bone over time.

This can cause severe mobility issues and can also lead to breathing difficulties as the ribcage becomes restricted. Unfortunately, there is currently no cure for FOP and treatment remains limited.

Kuru

Kuru is a rare and fatal brain disease that is caused by eating the brains of infected humans. It was first discovered in Papua New Guinea in the 1950s and was commonly associated with ritual cannibalism.

Symptoms of Kuru include muscle twitching and loss of coordination, and the disease can be fatal if left untreated. Thankfully, Kuru is now incredibly rare and was largely eradicated in the 1960s.

Harlequin Ichthyosis

Harlequin Ichthyosis is a severe genetic disorder that results in the skin becoming extremely thick and scaly. Infants born with this condition are covered in plates of thick, cracked skin that can make it difficult for them to move or breathe properly.

Unfortunately, Harlequin Ichthyosis has a very high mortality rate and most infants born with it do not survive more than a few weeks.

Alien Limb Syndrome

Alien Limb Syndrome is a neurological disorder that causes one or more limbs to move involuntarily. People with this condition often feel like their limbs are moving on their own and can’t be controlled.

This can be incredibly frustrating and can lead to difficulties with basic tasks such as eating or dressing. While there is no cure for Alien Limb Syndrome, medications can be used to help control the symptoms.

Porphyria

Porphyria is a group of rare genetic disorders that are caused by abnormalities in the enzymes that make heme, a crucial component of hemoglobin. Symptoms of Porphyria can include abdominal pain, skin sensitivity, and muscle weakness.

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In some severe cases, Porphyria can lead to nerve damage or even paralysis. Although there is no cure for Porphyria, certain medications can be used to manage the symptoms.

Microcephaly

Microcephaly is a condition where a baby’s head is smaller than expected, often due to abnormal brain development. This can lead to a variety of issues, including developmental delays and learning disabilities.

In some cases, Microcephaly can also be a sign of other underlying health conditions. While there is no cure for Microcephaly, early intervention and therapy can help improve outcomes for affected children.

Polio

Polio is an infectious disease that primarily affects young children. It is caused by a virus that attacks the nervous system, leading to muscle weakness or paralysis.

While most people who contract Polio do not experience any symptoms, some may develop paralysis in the legs or arms. Thankfully, Polio can now be effectively prevented through vaccination.

Narcolepsy

Narcolepsy is a chronic neurological disorder that affects a person’s ability to regulate their sleep-wake cycle.

People with Narcolepsy often experience sudden and uncontrollable bouts of sleepiness during the day, as well as sudden muscle weakness or paralysis. While there is no cure for Narcolepsy, medications and lifestyle changes can help manage the symptoms and improve quality of life.

Cystic Fibrosis

Cystic Fibrosis is a genetic disorder that affects the lungs, digestive system, and other organs. People with cystic fibrosis often experience chronic lung infections and have difficulty digesting food properly.

While there is no cure for Cystic Fibrosis, certain medications and therapies can help manage the symptoms and improve outcomes.

Batten Disease

Batten Disease is a rare and fatal neurological disorder that primarily affects children. It causes the brain to gradually lose function, leading to vision loss, seizures, and loss of coordination.

Unfortunately, there is currently no cure for Batten Disease and life expectancy for affected children is typically only into their teens or early twenties.