Acquired haemophilia is a rare but potentially life-threatening bleeding disorder that can appear suddenly in people who have never had bleeding problems before. Unlike the inherited form of haemophilia, this condition develops when the body’s immune system mistakenly attacks its own clotting factors.

Activated PI3 kinase delta syndrome is a rare inherited immune disorder that leaves people vulnerable to repeated infections and other serious health problems. First identified in 2013, this condition affects the immune system’s ability to fight bacteria and viruses, often leading to a complex pattern of symptoms that can vary widely from one person to another.

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury that causes fluid to build up in the tiny air sacs of your lungs, leading to dangerously low oxygen levels in your blood. This serious condition usually develops within hours to days after a major illness or injury, and requires immediate intensive care treatment.

Adrenocortical carcinoma is a rare but aggressive cancer that develops in the outer layer of the adrenal glands, small organs that sit on top of your kidneys and produce vital hormones. Though it affects only about 1 or 2 people per million each year, this cancer can cause serious health problems by releasing excessive amounts of hormones or growing large enough to press on nearby organs.

Adrenogenital syndrome, also known as congenital adrenal hyperplasia, is a group of genetic disorders that affects the adrenal glands and their ability to produce vital hormones your body needs to function properly.

Advanced systemic mastocytosis is a rare and serious blood disorder where abnormal mast cells build up uncontrollably in various organs, potentially causing organ damage and life-threatening complications.

Aicardi-Goutières syndrome is a rare inherited disease that primarily attacks the brain’s white matter, triggering an immune system response that mistakenly turns against the body itself, leading to serious neurological problems that can appear at birth or develop within the first months of life.

Alagille syndrome is a genetic condition affecting multiple organs, most notably causing malformed or too few bile ducts in the liver, leading to bile buildup that damages liver tissue. This rare disorder can also affect the heart, eyes, bones, kidneys, and blood vessels, with symptoms ranging from mild to life-threatening.

Alexander disease is a rare genetic disorder that progressively damages the nervous system, causing the protective coating around nerve fibers in the brain to deteriorate over time and leading to serious neurological problems.

Alport’s syndrome is a rare genetic condition that affects the kidneys, ears, and eyes. It occurs when the body cannot produce normal proteins needed for healthy kidney function, which can lead to kidney failure over time.

Alternating hemiplegia of childhood is a rare brain disorder that causes sudden, temporary paralysis in young children, along with developmental challenges and other symptoms that can significantly impact their quality of life.

Amyotrophic lateral sclerosis is a progressive nervous system disease that affects nerve cells in the brain and spinal cord, leading to loss of muscle control. While there is currently no cure, treatments and supportive care can help manage symptoms and improve quality of life.

Anaplastic thyroid cancer is one of the most aggressive forms of cancer affecting the thyroid gland, growing rapidly and often spreading to other parts of the body before diagnosis, yet recent advances in targeted treatments offer new hope for some patients.

Andersen-Tawil syndrome is a rare genetic disorder that affects the muscles, heart, and physical development, causing episodes of muscle weakness, abnormal heart rhythms, and distinctive physical features in those affected.

Angelman syndrome is a rare genetic disorder that primarily affects the nervous system, causing severe developmental delays, intellectual disability, and problems with movement and speech. Despite these challenges, people with this condition often have a remarkably happy demeanor, with frequent smiling and laughter.

Angiosarcoma is a rare and aggressive cancer that starts in the lining of blood vessels or lymph vessels, most often appearing on the skin of the head and neck but capable of developing almost anywhere in the body.

Metastatic angiosarcoma is an advanced and extremely aggressive form of a rare cancer that originates from blood or lymph vessel cells and has spread to other parts of the body, with survival measured in months rather than years.

Angiosarcoma is a rare and aggressive cancer that begins in the cells lining blood vessels or lymph vessels. When detected before it spreads to other parts of the body, it is called non-metastatic angiosarcoma. Understanding this condition, its symptoms, and treatment options can help patients make informed decisions about their care.

Recurrent angiosarcoma is a highly aggressive cancer that returns after initial treatment, presenting one of the most challenging situations in cancer care. Understanding the nature of recurrence and available treatment options can help patients and their families navigate this difficult diagnosis.

Antisynthetase syndrome is a rare condition where your immune system mistakenly attacks your own body, causing inflammation in muscles, joints, lungs, skin, and blood vessels.

Antithrombin III deficiency is a rare blood disorder that disrupts the body’s natural ability to control blood clotting, putting people at risk for dangerous blood clots that can affect the legs, lungs, and other vital organs.

Arterial tortuosity syndrome is a rare genetic disorder that causes blood vessels to become twisted, elongated, and prone to serious complications that can affect the heart, brain, and other vital organs.

Atypical haemolytic uraemic syndrome is a rare, potentially life-threatening condition where the immune system mistakenly attacks blood vessel cells, forming dangerous clots that can damage kidneys and other vital organs.

Basal cell naevus syndrome is a rare inherited condition that causes multiple skin cancers to develop from a young age, along with cysts in the jaw and other abnormalities throughout the body.

Behcet’s syndrome is a rare condition that causes inflammation of blood vessels throughout the body, leading to painful mouth sores, genital ulcers, eye problems, and many other symptoms that can come and go unpredictably.

Biotinidase deficiency is a treatable inherited disorder where the body cannot recycle biotin, a vital vitamin needed for breaking down food into energy. Early diagnosis and simple daily treatment with biotin supplements can prevent serious health problems and allow children to develop normally.

Brain stem glioma is a type of tumor that develops in the brainstem, the critical area connecting your brain to your spinal cord. While these tumors most commonly affect children, they can also occur in adults, and their behavior and outlook vary greatly depending on their location and how fast they grow.

Breast angiosarcoma is a very rare and aggressive cancer that starts in the cells lining blood or lymph vessels in the breast. While it accounts for less than 1% of all breast cancers, people who have received radiation therapy for breast cancer face a higher risk of developing this disease years after treatment.

Breast angiosarcoma that has spread to other parts of the body is a rare and aggressive form of cancer that presents unique challenges for patients and doctors. Understanding this disease and available treatment options can help patients navigate their journey with greater confidence.

Bronchiolitis obliterans syndrome is a serious lung condition that causes the smallest airways in the lungs to become inflamed, damaged, and scarred, making it difficult to breathe. It most commonly occurs after organ transplants, but can also develop from breathing in harmful chemicals or after severe infections.

Bronchopulmonary dysplasia is a serious lung condition that primarily affects babies born too early, when their lungs are not yet fully developed. While these tiny infants often need life-saving oxygen therapy and breathing support, this same treatment can damage their delicate lungs over time, leading to long-term breathing difficulties.

Burkitt’s lymphoma is a rare but fast-growing cancer that develops in the body’s infection-fighting system. Though it can be life-threatening because of how quickly it spreads, most people respond well to treatment and can go into long-term remission when diagnosed and treated right away.

CADASIL is a rare inherited disorder that affects the blood vessels in the brain, causing symptoms that can include migraine headaches, strokes, and changes in memory and thinking. Understanding this condition can help patients and families navigate the challenges it presents.

Carcinoid syndrome is a rare condition that occurs when certain tumors release large amounts of hormones and other chemicals into your bloodstream, causing a range of uncomfortable and sometimes serious symptoms that can significantly affect your daily life.

Castleman’s disease is a rare group of disorders where the immune system becomes overactive, leading to enlarged lymph nodes and, in some forms, widespread inflammation that can damage vital organs throughout the body.

Primary sclerosing cholangitis is a rare liver disease where inflammation causes scarring and narrowing of the bile ducts, eventually leading to serious liver damage. While many people show no symptoms at first, the disease progresses slowly over 10 to 15 years and can result in liver failure and increased cancer risk.

Chondrosarcoma is a rare type of bone cancer that begins in cartilage, the connective tissue protecting joints and bones. It grows slowly in most cases, but certain types can be aggressive and difficult to treat. Understanding the symptoms, causes, and treatment options is essential for anyone affected by this condition.

Chondrosarcoma with metastatic disease represents a serious form of bone cancer where the tumor has spread beyond its original location to other parts of the body, most commonly the lungs and other bones, presenting significant challenges for treatment and survival.

Chordoma is a rare type of bone cancer that grows slowly but can be very difficult to treat because it develops in delicate areas near the spine and skull, close to critical structures like the brain, spinal cord, and major blood vessels.

Choroid melanoma is the most common cancer that develops inside the adult eye, yet it remains a rare condition that often goes unnoticed until detected during a routine eye examination.

Chronic granulomatous disease is a rare genetic condition that weakens the immune system’s ability to fight certain infections, leaving people vulnerable to serious bacterial and fungal infections throughout their lives.

Combined immunodeficiencies are a group of rare genetic disorders that affect both major types of infection-fighting white blood cells, making it difficult for the body to defend itself against infections.

Congenital generalised lipodystrophy is a rare inherited condition where a child is born with almost no body fat. This severe lack of fat tissue causes the body to store fat in places it shouldn’t, leading to serious health problems including diabetes, liver disease, and heart complications.

Congenital hypotransferrinaemia is an extremely rare blood disorder that creates a puzzling medical paradox: patients suffer from severe anemia while simultaneously accumulating dangerous amounts of iron in their organs.

Congenital nephrogenic diabetes insipidus is a rare inherited disorder where the kidneys cannot respond properly to a natural hormone, causing the body to produce large amounts of dilute urine and leading to excessive thirst and the risk of severe dehydration.

Crigler-Najjar syndrome is a rare inherited condition where the liver cannot properly break down bilirubin, a substance produced when red blood cells are broken down. This leads to a dangerous buildup in the body that can cause serious brain damage if not treated promptly.

Cystic fibrosis is a genetic condition that causes thick, sticky mucus to build up in the body, affecting the lungs, digestive system, and other organs. While there is no cure yet, advances in treatment have dramatically improved life expectancy, with many people now living into their 50s, 60s, and beyond.

Cystic fibrosis is a genetic disease that causes thick, sticky mucus to build up in the lungs and other organs, leading to breathing difficulties and frequent infections that require lifelong management and care.

Cytokine release syndrome is a serious inflammatory response that happens when your immune system releases too many signaling proteins into your bloodstream, causing widespread inflammation that can damage organs and tissues throughout the body.

Ehlers-Danlos syndrome is a group of inherited disorders that affect the connective tissue throughout your body, causing symptoms like overly flexible joints, stretchy skin, and easy bruising that can significantly impact daily life.

Autoimmune encephalitis is a group of conditions where the body’s immune system mistakenly attacks healthy brain cells, causing inflammation that can lead to memory loss, seizures, psychiatric symptoms, and other serious neurological problems.

Epidermolysis bullosa is a rare inherited condition that causes the skin to become extremely fragile, blistering and tearing from even the slightest touch or friction.

Erdheim-Chester disease is a rare blood cancer that occurs when the body produces too many immune cells called histiocytes, which then accumulate in organs and tissues throughout the body. This condition can range from causing no symptoms at all to life-threatening complications, depending on which organs are affected.

Ewing’s sarcoma is a rare and aggressive cancer that most often affects children and teenagers, beginning as abnormal cell growth in bones or nearby soft tissues and requiring prompt treatment with chemotherapy, surgery, or radiation therapy.

Metastatic Ewing’s sarcoma is a challenging condition in which cancer that began in bone or soft tissue has spread to distant parts of the body, most commonly the lungs, presenting unique treatment challenges and requiring aggressive therapy approaches.

When Ewing’s sarcoma returns after treatment or does not respond to initial therapy, patients face a challenging situation with limited standard treatment options. Understanding what recurrence means and what approaches are available can help patients and families navigate this difficult journey.

Fabry disease is a rare inherited condition where a specific type of fat builds up in your body’s cells because you lack a crucial enzyme to break it down. This buildup can affect many organs including your heart, kidneys, and nervous system, causing pain, organ damage, and potentially life-threatening complications.

Factor IX deficiency, also known as Hemophilia B or Christmas disease, is a rare inherited bleeding disorder where the blood cannot clot properly due to missing or insufficient clotting factor IX protein, affecting mainly males and requiring lifelong management.

Factor VIII deficiency, also known as hemophilia A, is an inherited bleeding disorder that prevents blood from clotting properly. This condition causes prolonged and excessive bleeding either spontaneously or after injuries, making everyday activities and medical procedures potentially dangerous without proper treatment.

Familial amyotrophic lateral sclerosis (fALS) is an inherited form of ALS that runs in families, accounting for about 5-10% of all ALS cases. Unlike the more common sporadic form, fALS is caused by genetic mutations passed down from parents to children, often striking at a younger age and offering new hope for targeted gene therapies.