Osteopoikilosis is a rare, mostly harmless bone condition where many tiny “bone islands” grow inside different bones. Doctors see these as small, round or oval ...

Disseminated Dermatofibrosis with Osteopoikilosis is a rare, inherited disorder that affects the skin and the bones. On the skin, people develop small, firm ...

Buschke–Ollendorff syndrome is a rare, inherited condition that affects the skin and the bones. In the skin, people develop small, firm bumps called connective ...

Giant acuminate warts are very large, cauliflower-like growths that form on the genital or anal skin. They are caused by certain types of the human ...

Buschke-Löwenstein giant condyloma is a very large, wart-like growth that forms in the anogenital area. It grows slowly but can become huge and look like a ...

Anogenital verrucous carcinoma of Buschke–Löwenstein is a large, cauliflower-like, slow-growing tumor in the genital or anal area. It develops from ...

Buschke–Löwenstein tumor is a very large, slow-growing, warty tumor in the genital or anal area. Doctors also call it giant condyloma acuminatum. It is caused ...

Searle’s ulcer is an infection of the skin and the tissue under the skin caused by a bacterium called Mycobacterium ulcerans. It starts as a firm, painless ...

Mossman ulcer is a slow-growing bacterial infection that starts as a painless lump, patch, or swelling under the skin. Over weeks, the skin thins and breaks ...

Daintree ulcer is a skin infection that makes a painless lump or swelling that slowly turns into a deep ulcer (open sore). It is caused by a germ called ...

Cutaneous Mycobacterium ulcerans infection, also called Buruli ulcer, is a skin disease caused by a slow-growing bacterium named Mycobacterium ulcerans. The ...

Bairnsdale ulcer is a skin and soft-tissue infection caused by a bacterium named Mycobacterium ulcerans. The germ makes a toxin called mycolactone that damages ...

Buruli ulcer is a long-lasting skin infection caused by a bacterium called Mycobacterium ulcerans. The germ makes a toxin (mycolactone) that quietly destroys ...

Stomatopyrosis means a constant or frequent burning, scalding, or tingling feeling in your mouth even though the lining of the mouth looks normal. The burning ...

Stomatodynia means a long-lasting burning, scalding, or tingling pain inside the mouth even though the mouth looks normal when a dentist or doctor examines it. ...

Orodynia means an ongoing burning, scalding, stinging, or tingling pain inside the mouth, usually with a normal-looking mouth on exam. Many people feel it on ...

Burning mouth syndrome is long-lasting mouth pain that feels like burning, scalding, tingling, or rawness even though the mouth looks normal. It often affects ...

Burkitt lymphoma is a very fast-growing cancer of mature B lymphocytes. The tumor cells divide extremely quickly, so the disease can double in size in hours to ...

Burkitt's type malignant lymphoma - small non-cleaved (historically called “small non-cleaved” lymphoma; now classified as Burkitt lymphoma) is a very ...

The hemoglobin A1c test—also known as glycated hemoglobin, glycosylated hemoglobin, HbA1c, or simply A1c—is used to measure an individual's glucose control ...

Burkitt’s tumor is a very fast-growing cancer of B lymphocytes (B cells), which are white blood cells that normally help your body fight infection. The cancer ...

Burkitt’s lymphoma is a very fast-growing cancer of the immune system. It starts in B lymphocytes, which are white blood cells that help your body make ...

Burkitt leukemia is the leukemic (blood and bone-marrow) form of Burkitt lymphoma, a very fast-growing cancer of B-lymphocytes. In older systems it was called ...

Burkitt lymphoma is a very fast-growing cancer of mature B-lymphocytes. The cancer cells usually carry a change in their DNA called an IG::MYC ...

Burkitt lymphoma is a very fast-growing cancer of B lymphocytes, a type of white blood cell that normally helps your body fight infections. In this disease, a ...

Bullous pemphigoid is an autoimmune skin disease. “Autoimmune” means the body’s defense system makes antibodies that attack its own skin. In bullous ...

Bullous impetigo is a fast-spreading bacterial skin infection that makes large, fragile blisters filled with clear or yellow fluid. These blisters break easily ...

Hereditary Bullous Dystrophy, Macular Type is a rare eye disease that you are born with. It mainly affects the clear front window of the eye called the cornea. ...

Macular corneal dystrophy (MCD) is an inherited eye disease where cloudy deposits develop in the clear front window of the eye (the cornea). These gray-white ...

JAK2-related Budd–Chiari syndrome (BCS) means the blood cannot leave the liver properly because the hepatic veins (the veins that drain the liver) or the ...

Hepatic vein obstruction means the blood leaving the liver cannot flow out normally through the hepatic veins into the inferior vena cava (IVC) and then to the ...

F5-related Budd–Chiari syndrome means Budd–Chiari syndrome (BCS) that happens in a person who carries the Factor V Leiden (F5 G1691A) mutation. In BCS, blood ...

Budd–Chiari syndrome means the blood leaving your liver through the hepatic veins (and sometimes the nearby inferior vena cava) is blocked. The blockage is ...

Bubonic plague is a severe bacterial infection caused by Yersinia pestis. It usually spreads to people through the bite of infected fleas that live on wild ...

Bruton tyrosine kinase (BTK) deficiency is a rare, inherited immune disorder. It mainly affects boys. The body cannot make mature B lymphocytes (B cells), the ...

Bruton agammaglobulinemia tyrosine kinase deficiency is a genetic condition that mainly affects boys. A change (mutation) in a gene on the X chromosome called ...

X-Linked Recessive Agammaglobulinemia is a rare genetic condition that mainly affects boys and stops the body from making antibodies. Antibodies are proteins ...

Bruton-type agammaglobulinemia is a genetic immune system disease in which the body cannot make mature B-cells and, therefore, makes almost no antibodies ...

Monoamine oxidase A deficiency is a very rare genetic condition that mostly affects boys and men. People with this condition have lower activity of an enzyme ...

X-Linked Recessive Brunner Syndrome is a very rare genetic condition. It mostly affects boys and men. It happens when a gene on the X chromosome called MAOA ...

Antisocial behavior means a long-lasting pattern of actions that ignore the rights and feelings of other people and the rules of society. People who show ...

Brunner syndrome is a very rare, X-linked genetic condition in which the MAO-A enzyme does not work properly. MAO-A normally breaks down brain chemicals such ...

CACNB2-Related Brugada Syndrome Type 4 is a heart-rhythm disorder that can cause dangerous fast rhythms in the lower chambers of the heart (ventricular ...

Brugada syndrome caused by mutation in CACNB2 is a heart rhythm condition that makes the heart’s electrical system unstable. It can cause dangerous fast ...

Brugada syndrome 4 is a heart rhythm condition. It affects the tiny electrical signals that make your heart beat. In Brugada syndrome, those signals do not ...

CACNA1C-related Brugada syndrome is a heart rhythm problem. It makes the lower chambers of the heart (the ventricles) beat in a dangerous way. It can cause ...

Brugada syndrome (BrS) is a heart rhythm condition. It affects the heart’s electrical system and can cause dangerous fast rhythms from the lower chambers ...

Brugada syndrome 3 is a genetic heart-rhythm disorder caused by changes (variants) in a calcium-channel gene called CACNA1C. The gene change reduces the ...

Sudden unexplained nocturnal death syndrome (SUNDS) is a sudden death that happens during sleep in people who seemed healthy and whose autopsy shows no clear ...

Sudden unexplained death syndrome is also written as SUDS or SUDY (sudden unexplained death in the young). When the death happens during sleep it is often ...

Pokkuri Death Syndrome (PDS) is a traditional Japanese name for sudden, unexpected death during sleep in people with no obvious heart disease on autopsy. ...

Idiopathic ventricular fibrillation, Brugada type is a heart rhythm problem where the lower chambers of the heart (the ventricles) suddenly beat in a very fast ...

“Dream disease” is known as dream-related sleep disorders, especially nightmare disorder (also called dream anxiety disorder) and other parasomnias that center ...

Brugada-type idiopathic ventricular fibrillation means a person has very fast, chaotic heartbeats (ventricular fibrillation) even though the heart looks normal ...

Bangungut is a Filipino word that literally relates to a terrifying nightmare. In medicine, it is the local name for Sudden Unexplained Nocturnal Death ...

Brugada syndrome is an inherited heart rhythm problem. It affects the way tiny “ion channels” move electricity in the heart’s cells. This can create a special ...

PLOD2-Related Bruck Syndrome (Bruck Syndrome Type 2, BRKS2) is a very rare genetic bone disorder where two problems happen together: babies are born with stiff ...

Bruck syndrome caused by mutation in PLOD2 is a very rare inherited bone and joint condition. Babies are usually born with stiff joints (contractures) and ...

Bruck syndrome 2 is a very rare genetic condition that combines two big problems: (1) bones that break easily (like osteogenesis imperfecta) and (2) tight ...

Osteogenesis imperfecta-congenital joint contractures syndrome combines the bone fragility of osteogenesis imperfecta with congenital (from birth) joint ...

Osteogenesis imperfecta with congenital joint contractures is a very rare, inherited bone and connective-tissue disorder in which a baby is born with stiff ...

Bruck syndrome is a rare genetic bone and joint disorder. Babies are born with stiff joints (called contractures) and bones that break easily. Doctors describe ...

Undulant fever—also called brucellosis or Malta fever—is a bacterial infection you can get from contact with infected animals or from eating or drinking ...

Maltese fever is an infection in humans caused by Brucella bacteria. These germs live mainly in animals such as goats, sheep, cows, pigs, and dogs. People get ...

Brucellosis is an infection you get from Brucella bacteria. People are usually infected by unpasteurized milk or dairy, or by touching infected animals or ...

CYLD cutaneous syndrome (CCS) is a rare inherited condition in which people develop many small skin tumors—most often cylindromas, spiradenomas, and ...

Brooke–Spiegler syndrome is a rare inherited condition that causes many small skin tumors to grow over time, most often on the scalp, face, and neck. These ...

Bronchiolitis obliterans with obstructive pulmonary disease is a small-airway disease also called constrictive bronchiolitis or obliterative bronchiolitis. It ...

Idiopathic bronchiolitis obliterans with organizing pneumonia is an inflammatory lung disease. The tiny airways (bronchioles) and the neighboring air sacs ...

Cryptogenic organizing pneumonitis (COP)—also called cryptogenic organizing pneumonia or bronchiolitis obliterans organizing pneumonia (BOOP)—is an ...

Cryptogenic organizing pneumonia (COP) is an inflammatory lung disease. “Cryptogenic” means the trigger is unknown. “Organizing pneumonia” describes the way ...

Bronchiolitis Obliterans Organizing Pneumonia (BOOP)—most often called Organizing Pneumonia (OP), and Cryptogenic Organizing Pneumonia (COP) is a healing ...

Brody myopathy (also called Brody disease) is a rare, inherited muscle condition where muscles have trouble relaxing after they contract. People often feel ...

Type VIB Ehlers-Danlos syndrome is a rare, inherited connective-tissue disorder caused by pathogenic variants in the FKBP14 gene. It typically presents with ...

Brittle cornea syndrome type 1 (BCS1) is a very rare, inherited connective-tissue disorder where the clear front window of the eye (the cornea) is extremely ...

Brittle cornea syndrome is a very rare inherited disorder that makes the clear front window of the eye (the cornea) extremely thin and fragile. Because the ...

“X-linked mental retardation, Reish type” is an old name for a rare, inherited condition first described by Dr. Reish and colleagues. Today it is usually ...

BRESHECK (also written BRESEK) is a very rare genetic condition seen mostly in boys. It affects many parts of the body from birth. The name is an acronym that ...

Brain anomaly A brain anomaly is a difference in how the brain formed or looks. It can be very small or very large. It may affect thinking, movement, speech, ...

Brain anomaly, severe intellectual disability, ectodermal dysplasia, skeletal deformity, ear anomaly, kidney dysplasia syndrome.” Clinicians usually shorten ...

BRESEK syndrome is an extremely rare, inherited condition that affects many body systems from birth. The name is an acronym that summarizes its key features: ...

Breast angiosarcoma is a rare, fast-growing cancer that starts in the cells lining blood vessels or lymph vessels within the breast or the breast skin. Because ...

Sabiá hemorrhagic fever is a rare but severe viral illness caused by the Sabiá virus, a New World mammarenavirus (family Arenaviridae). It can lead to high ...

Brazilian hemorrhagic fever is a very rare viral illness. It is caused by the Sabiá mammarenavirus (SABV), an arenavirus found in South America. People usually ...

Branchio-otic dysplasia (BOS) is a rare genetic condition that affects how parts of the neck and ears form before birth. People with BOS often have tiny pits ...

Branchio-otic (BO) syndrome is part of the branchio-oto-renal (BOR) spectrum but without kidney malformations; it features branchial cysts/fistulae, ear ...

Lip pseudocleft–hemangiomatous branchial cyst syndrome is a birth-time (congenital) condition that affects how parts of the face, eyes, and neck form before a ...

Hemangiomatous branchial clefts–lip pseudocleft syndrome” describes a rare, inherited birth-defect pattern where parts of the neck, face, and eyes do not form ...

Branchio-Oculo-Facial Syndrome (BOFS) is a very rare genetic condition that affects the skin and tissues of the neck (“branchio-”), the eyes (“oculo-”), and ...

Branchio-Oculo-Facial Syndrome (BOFS) (also called Braddock-Carey syndrome/Braddock syndrome). It is a rare genetic condition caused by TFAP2A gene variants ...

Branchio-oculo-facial syndrome (BOFS) is a rare condition that starts before birth. It affects the face, neck, eyes, and nearby skin. Many babies have thin or ...

Mégarbané–Loiselet syndrome is an extremely rare genetic condition reported in a single family. It causes birth defects of the branchial arches in the neck and ...

Branchiogenic hearing loss syndrome refers to a group of birth conditions where parts of the neck and ear that grow from the branchial arches (structures that ...

Branchiogenic deafness syndrome is a very rare condition present from birth. It affects parts of the neck that come from the second branchial arch (a structure ...

Melnick–Fraser syndrome is a rare, inherited condition that affects the neck (branchial arches), the ears (outer, middle, and inner parts), and the kidneys and ...

Branchio-oto-renal (BOR) dysplasia is a genetic condition that affects the neck (branchial area), the ears (hearing system), and the kidneys. Children or ...

Branchio-oto-renal (BOR) syndrome is a genetic condition that mainly affects the neck, the ears, and the kidneys. “Branchio” refers to tissues in the side of ...

Autism–epilepsy syndrome due to branched-chain ketoacid dehydrogenase kinase deficiency (BCKDK deficiency) is a rare genetic condition that affects how the ...

Branched-chain keto acid dehydrogenase kinase (BCKDK) deficiency is a rare genetic disorder in which the BCKDK enzyme does not work well. BCKDK normally puts a ...

Choreoathetosis-hypothyroidism-neonatal respiratory distress syndrome is a rare genetic condition that affects three organs at once: the brain, the lungs, and ...

Choreoathetosis with congenital hypothyroidism and neonatal respiratory distress syndrome this triad sits on the spectrum of NKX2-1–related disorders, ...

Choreoathetosis and congenital hypothyroidism with pulmonary dysfunction also call it brain–lung–thyroid (BLT) syndrome or an NKX2-1–related disorder, because ...

Brain-Lung-Thyroid syndrome is a rare genetic condition that can affect the brain (movement control and development), the lungs (breathing), and the thyroid ...

Goossens–Devriendt syndrome (also called brain malformation–congenital heart disease–postaxial polydactyly syndrome) is a very rare genetic condition first ...

Brain malformation–congenital heart disease–postaxial polydactyly syndrome (also known as Goossens-Devriendt syndrome) is a very rare genetic condition. A baby ...

Parkinsonism-dystonia 2, infantile-onset (PKDYS2) is a very rare genetic brain disorder that starts in infancy. It happens when a child inherits two faulty ...

Brain monoamine vesicular transport disease is the rare genetic condition also called brain dopamine–serotonin vesicular transport disease, VMAT2 deficiency, ...

Brain dopamine-serotonin vesicular transport disease is a very rare genetic condition where a tiny “transport pump” in brain cells—called VMAT2—does not work ...

Prolonged electroretinal response suppression (PERRS) is a rare eye condition. After light shines in the eye, the retina should recover quickly. In PERRS, the ...

Brachytelephalangy-dysmorphism-Kallmann syndrome is a very rare condition that affects body shape (especially the hands and face) and the hormones that start ...

Autosomal dominant brachyolmia type 3 (often abbreviated BCYM3) is a rare, inherited bone growth disorder that mainly affects the spine. Children usually look ...

Brachyrachia means an abnormally short spine. In this condition, the bones of the spine (the vertebrae) are short and flattened, so the whole trunk looks short ...