Rare Health Conditions You Probably Didn't Know Exist

Living with any health condition is no easy feat. Yet, to say there's a big difference between living with a more "common" or widely known condition versus a rare one is quite an understatement. According to the National Organization for Rare Disorders (NORD), a rare disease is defined as one present in less than 200,000 Americans. These diseases can be particularly devastating, with many being fatal in early childhood. However, despite their individual rarity, collectively, rare diseases are surprisingly common, with over 7,000 identified conditions affecting roughly 25 to 30 million Americans and 350 million people worldwide.

Unlike some of the most common health disorders (think diabetes, allergies, heart disease, or even cancer), which have been studied for years and have, for the most part, a wide array of treatment options, rare diseases are somewhat of an uncharted or overlooked territory in the medical world, often with complex symptoms that pose significant challenges for diagnosis and treatment. In fact, you could say that the latter is one of the biggest challenges for those affected by rare diseases, seeing that more than 90% of them do not have an FDA-approved treatment, leaving people with few options for managing their conditions. This highlights the need to raise awareness about these conditions in the hopes of spurring more research to find effective solutions. Here's a list of 12 rare health conditions you probably didn't even know existed.

Proteus syndrome is an extremely rare condition known to have affected less than 100 people worldwide. It is caused by a random mutation in a gene involved in growth regulation, leading to its characteristic physical traits, which include the overgrowth of bones, joints, skin, fatty tissue, organs, and blood vessels, among others (via NORD). These overgrowths usually occur between 6 and 18 months and are typically asymmetrical, meaning they may only affect one limb or side of the body. Common sites of bone overgrowth include the skull, spine, and bones in the arms, legs, feet, and hands. Other manifestations can include the development of cysts or tumors.

According to the National Human Genome Research Institute (NHGRI), since the syndrome's overgrowths can change the shape of the person's body, it was named after the ancient Greek god Proteus, who could also change his own shape. Since people with Proteus syndrome have different manifestations, treatment focuses on managing each symptom and its potential complications. Thus, it tends to require a team of multiple specialists, such as orthopedists, to fix bone problems or dermatologists to treat skin changes. In some cases, surgery might be needed.

Despite water being essential for life, some people may actually be allergic to it, a condition known as aquagenic urticaria. According to a case report published in the Annals of Dermatology, people with aquagenic urticaria develop small, red, itchy welts or hives on the skin areas that come into contact with water. This tends to be more common in women, and they typically appear on the neck, shoulders, trunk, arms, and back, lasting for 30 minutes and up to one hour before gradually fading away. Moreover, the reaction can occur with contact with any type of water, including tap water (think showers or baths) and rain, regardless of the temperature. However, the report noted that sweat did not trigger any response.

While the exact cause of aquagenic urticaria is still unknown, various theories propose different mechanisms. For instance, according to an article published in the Journal of Asthma and Allergy, one theory suggests that water reacts with oil-producing glands in the skin, triggering the release of histamine from allergy cells and causing hives. In contrast, another one states that some people may have allergy-causing substances in the skin that are water-soluble, causing the same histamine release when coming in contact with water. Treatment for water allergy focuses on symptom control with anti-allergy medications. In some cases, using oil- or petrolatum-based creams to create a barrier on the skin may help reduce or prevent a reaction.

As its name implies, cold allergy, or urticaria, is an allergic reaction that develops on the skin after exposure to cold temperatures from foods, drinks, objects, water, or even weather conditions. There are two types of cold urticaria: acquired or essential and familial or hereditary, depending on whether other family members have it. They also differ in the onset of the symptoms, with the first showing them within minutes and lasting just a couple of hours and the latter appearing up to 48 hours later and lasting for a couple of days (via the Cleveland Clinic).

Per NORD, the causes of cold allergy can be either unknown, due to an autoimmune disorder in which the body mistakenly attacks its own healthy tissues, or due to a genetic inheritance where one copy of a mutated gene inherited from one parent causes the condition. Symptoms of cold allergy typically include red, itchy welts on areas of skin that have been exposed to the cold. Yet, they may also include headache, anxiety, fever, tiredness, and, in more severe cases, fainting, palpitations, and wheezing or shortness of breath. Living with cold urticaria requires careful management, such as wearing warm clothes and avoiding bathing or swimming in cold water. Its treatment tends to rely on antihistamines to prevent or control allergic reactions.

Can you really get drunk without drinking alcohol? As unbelievable as it may sound, this might be a reality for people with auto-brewery syndrome. This condition, also known as gut fermentation syndrome or drunkenness disease, is characterized by the fermentation of carbs in the gut due to the overgrowth of certain types of yeast, resulting in the internal production of ethanol. As a result, people can become intoxicated without consuming any alcoholic beverages, causing significant impacts on their daily lives (via Healthline). According to the National Library of Medicine (NLM), the underlying cause of the syndrome has been identified as a disruption of the gut microbiome due to antibiotic abuse or high-carb diets, which provide the substrate for fermentation. However, the fermentation may also occur in the oral cavity or urinary system.

Per Healthline, symptoms of auto-brewery syndrome resemble being drunk or hungover and can vary in severity. Common symptoms include dizziness, confusion, nausea, vomiting, headaches, loss of coordination, mood changes, memory problems, and extreme fatigue. Treating auto-brewery syndrome starts by stabilizing the person's high blood alcohol levels and prescribing antifungal drugs to eliminate the yeast imbalance. Additionally, dietary modifications are essential. These involve following a low-carb, low-sugar diet. Lastly, supplementing with probiotics can help restore a healthy balance of gut microbiota (via NLM).

Porphyria cutanea tarda (PCT), often referred to as vampire syndrome, is a rare blood disorder that affects the skin and, sometimes, the liver. It happens because certain enzymes that convert chemicals called porphyrins into heme are not working properly, resulting in a porphyrin overload. Heme is the component in red blood cells that carries oxygen (via NORD). The accumulation of porphyrins in the skin causes them to absorb sunlight, damaging the skin and leading to the syndrome's common symptoms, which include painful blistering, peeling, swelling, and redness of the skin. Thus, the vampire reference comes from PCT's effect on the skin when exposed to sunlight (photosensitivity).

According to the Genetic and Rare Diseases Information Center (GARD), PCT is a multifactorial disorder that might be caused by a mix of a genetic mutation and lifestyle and environmental factors that disrupt a person's porphyrin metabolism, such as smoking, consuming alcohol, and having an iron overload. Per NORD, treatment for PCT focuses on reducing porphyrin levels, with therapeutic phlebotomies or regular blood removals to reduce iron levels (which in turn lowers porphyrin production) being the preferred method. In addition, people with PCT are advised to avoid environmental triggers and protect their hands and face from sunlight by donning long-sleeved shirts, gloves, wide-brimmed hats, and sunglasses.

Fatal familial insomnia (FFI) is an extremely rare and degenerative disorder caused by a genetic mutation that primarily affects the brain, namely the part that controls the sleep-wake cycle (via GARD). Per the site, it has been diagnosed in less than 1,000 people in the U.S. As its name suggests, FFI is both fatal and runs in families, meaning that it can be passed from parents to their children. According to NORD, FFI can lead to severe sleep disturbances and a range of physical and mental symptoms. What starts with a progressively worsening insomnia may ultimately result in coma and death. Other symptoms include hallucinations, confusion, memory problems, loss of coordination, excessive sweating, high blood pressure, and tachycardia.

Unfortunately, there is currently no cure for FFI. Thus, the main focus of its treatment is to tend to the person's specific symptoms, as well as providing supportive care, often through an interdisciplinary approach between brain doctors, psychiatrists, and psychologists (via NORD). Per the NLM, since treatment does not stop the disease's progression, palliative care is often necessary to provide comfort and support to patients and their families.

Stone man syndrome, medically known as fibrodysplasia ossificans progressiva (FOP), is an extremely rare and disabling genetic disorder that affects about 800 people worldwide. Soft tissues such as muscles, tendons, and ligaments progressively turn into bone, hence the name (via GARD). The onset of symptoms typically begins in childhood, and a trait that might help diagnose the condition is when babies are born with abnormal big toes.

With FOP, abnormal bone development happens due to a mutation in a gene that regulates bone growth. It may occur after a viral illness or a minor injury that leads to painful swelling and inflammation (also known as a flare-up), which can happen anywhere in the body, although more commonly in the neck, shoulders, or back. During a flare-up, the affected tissue slowly hardens to bone. Over time, this process can lead to a "second skeleton" forming, which can immobilize joints and, thus, severely limit mobility (per NORD). Given the rarity of the disease, there is still no available cure, and treatment usually centers around pain management and preventing flare-ups by avoiding activities that might cause injuries. Unfortunately, since the ossification process starts at such an early age, people with FOP usually become bedridden during their last years of life (via Ada).

According to a study published in Neurology, walking corpse syndrome, or Cotard delusion (named after the French neurologist Jules Cotard, who first described the condition in the 1880s), is a rare mental disorder in which people believe that they are dead, do not exist, or have lost their internal organs or blood. Per the study, the syndrome is often seen in the context of psychiatric conditions, such as bipolar disorder and schizophrenia, as well as after a head injury or migraine.

Symptoms of Cotard delusion can range from mild to extreme. Some people may believe that they are dead, decomposing, or have lost vital body parts, while others might insist that they do not need to eat or take care of themselves because they are "already dead," leading to complications such as malnutrition, hopelessness, isolation, and detachment from reality, increasing the risk of self-harm or suicidal behavior (per Healthline). 

Cotard's delusion treatment typically involves a combination of drugs and psychotherapy. For instance, antidepressants, antipsychotics, and mood stabilizers may be prescribed to manage potential complications and symptoms related to any underlying psychiatric conditions. Additionally, cognitive-behavioral therapy (CBT) can also be beneficial in helping patients challenge their delusional beliefs and reconnect with reality. In severe cases, electroconvulsive therapy (ECT) has been reported to be effective, especially when these other treatments have failed.

Picture this: you wake up one day after hitting your head only to discover that your American accent has been "replaced" with a British one. While it may sound like something out of a movie, this condition is known as foreign accent syndrome (FAS). FAS is a rare brain disorder reported in just over 100 people worldwide in which people suddenly and involuntarily begin speaking with a perceived foreign accent (per the Cleveland Clinic). Despite the name, the affected person doesn't actually acquire a foreign accent but instead experiences changes in speech patterns, such as pitch, rhythm, and pronunciation, that resemble an accent from another language or region. This condition can be puzzling and distressing for both the affected individuals and those around them.

According to the University of Texas at Dallas, FAS often develops following central nervous system damage, such as stroke, brain injury, multiple sclerosis, or other conditions that affect the brain areas responsible for speech, and symptoms may worsen when the person is under emotional stress. Treating foreign accent syndrome starts by addressing the underlying cause of injury. Yet, speech therapy can be helpful in addressing changes in speech patterns and working towards more typical pronunciation and rhythm. In cases where FAS is associated with psychological factors, a combination of psychotherapy and medications may be beneficial (via the Cleveland Clinic).

Just as in Alice in Wonderland (the movie), in which Alice experiences a series of weird changes in her perception, such as growing very large or shrinking very small after consuming magical substances, a case review published in the Journal of Pediatric Neurosciences explains that Alice in Wonderland Syndrome (AWS) is characterized by an altered body image perception, with the illusion that the head and hands have grown disproportionately. Other symptoms include migraines, micropsia (where objects appear smaller than they are), macropsia (where objects appear larger), and feeling like time passes by either at a glacier pace or in the blink of an eye.

According to Healthline, AWS is a brain disorder in which the brain wrongly interprets sensory information. Yet, it is believed that migraines might be the leading cause. Other potential triggers include epilepsy, infections (such as Epstein-Barr virus), brain tumors, or the use of hallucinogenic drugs. Per the case review, chronic cases of AWS often resolve on their own. However, treatment should focus on managing the underlying conditions, such as migraines, infections, or epilepsy, to help reduce the frequency and severity of episodes. Eventually, if or once the underlying conditions are resolved, the syndrome may completely disappear (via Healthline).

Werewolves are mythical creatures described as humans who transform into wolves or wolf-like beings with an appearance featuring excessive hair or fur. For that reason, Hypertrichosis lanuginosa congenita, an extremely rare genetic condition characterized by excessive hair growth in areas that are not typically hairy in humans, is commonly referred to as "werewolf syndrome." According to the NLM, the hair can grow up to 10 centimeters long and can cover all over the body, including the face, with hands and feet being the only spared areas. Per GARD, this condition affects less than 1,000 people in the U.S.

Hypertrichosis lanuginosa congenita is caused by a mutation in the gene responsible for the development of hair follicles (via NLM). Other symptoms include delayed dental development, abnormal teeth and skin color, hearing impairment, and thick or bushy eyebrows (via GARD). Currently, werewolf syndrome has no cure, and treatment focuses on cosmetic approaches to manage symptoms and improve the quality of life. For example, hair removal techniques such as shaving or laser hair removal can help reduce the appearance of excessive hair. However, it is important to note that these are temporary solutions, as hair often regrows (via NLM).

As its name suggests, trimethylaminuria, colloquially known as fish odor syndrome, is a condition in which people emit a fish-like smell. According to a review published in the Journal of Clinical and Aesthetic Dermatology, the syndrome is caused by a metabolic malfunction that prevents the body from breaking down trimethylamine, a compound with a strong fishy scent. As a result, the compound accumulates in the body and generates the characteristic stinky smell when released through the breath, sweat, urine, and other bodily fluids. Per the review, the odor may become more intense in conditions that cause excessive sweating, such as exercise, fever, and stress.

The review explains that there is no cure for trimethylaminuria, but the condition can be managed through dietary and lifestyle modifications. On the one hand, people are advised to avoid foods high in trimethylamine and its precursors, such as seafood, eggs, chicken, mustard seeds, beef liver, and raw soybeans. On the other hand, NORD states that taking supplements like activated charcoal or copper chlorophyllin may help by reducing the absorption of trimethylamine in the gut. Also, using acidic soaps or body lotions can help minimize the smell. Lastly, severe cases may need antibiotics to reduce the amount of trimethylamine-producing bacteria in the gut.