q The Rarest Diseases in the World and How to Identify Their Symptoms - Harcourt Health

The Rarest Diseases in the World and How to Identify Their Symptoms

Being diagnosed with a rare disease comes with plenty of stress. Not only is their the life-threatening concern the disease itself poses, but being diagnosed with a rare disease means costly visits with specialized physicians and other medical expenses. Knowing you have the symptoms for a rare disease and being able to catch them before it grows worse can be ultimately beneficial for you.

With any illness, catching it early on means that you’re catching it at its weakest state and that you’re giving doctors more time to eradicate it from your body. So knowing about these diseases and their symptoms will best equip you in the event of a diagnosis. Here are some of the world’s rarest diseases and how to identify their symptoms.


Known most commonly as the blue skin disorder, methemoglobinemia is a blood disorder where an unusual amount of methemoglobin is produced. Methemoglobin is a type of hemoglobin—the protein in red blood cells— that allows for the absorption of oxygen. However, with methemoglobin, the hemoglobin carries oxygen but does not release it to other tissues and cells in the body. This disease can be hereditary and acquired (mostly from exposure to certain chemicals, medicines or foods). A normal person may contain around one percent of methemoglobin in their blood; someone with this disease would have about 10 to 20 percent.

Hutchinson-Gilford Progeria

Progeria is a rare disease characterised by rapid aging starting in childhood. It can stunt growth of a newborn and give young children the appearance of baldness and aged skin. Progeria can also give young individuals similar ailments to their older counterparts, like hip dislocation and joint pain. Life expectancy with this disease is 13-14 years, with many dying from heart attacks or strokes. This disease stems from a mutation of the LMNA gene, which isn’t inherited from the parent.


A rare disease that affects less than 200,000 people in the U.S. per year, myocarditis is caused by inflammation of the middle layer of the heart wall, more specifically the heart muscle called the myocardium. Myocarditis can reduce the amount of blood your heart is able to pump and cause rapid or abnormal heart beats known as arrhythmias. A viral infection is the most common cause of this disease, but it can also be in reaction to specific drugs. Having myocarditis awareness and knowing what effects this illness has can help you in being diagnosed with it early on.

Buerger’s Disease

A rare disease that most often affects young and middle-aged male smokers, Buerger’s Disease is characterized by a blockage of the veins and arteries of the extremities. This reduces blood flow to these areas and can lead to amputations. This disease occurs in short, quick attacks on the body. Its onset and full course may occur over one to four weeks. One way to recognize it early on is if you experience extreme pain in your lower arms and legs while at rest. If you’re someone impacted by this disease and who has had amputations, there are products like prosthetic socks that cater to your needs.

RPI Deficiency

Currently one of the rarest diseases in the world, RPI Deficiency, also known as Ribose-5-phosphate isomerase deficiency, is a human disorder caused by mutations to the pentose phosphate pathway enzyme ribose-5-phosphate isomerase. Little is known about the what exactly causes the mutation, though, connections have been drawn between patients with the disease and certain allelic combinations. Some symptoms of this disease include optic atrophy, involuntary eye movement, cerebellar ataxia, and seizures.