Bilateral parasagittal parieto-occipital polymicrogyria (BPPo-PMG) is a rare brain-development problem where the cortex forms too many tiny folds ...

Multicystic renal dysplasia (MCDK) is a birth condition where one kidney (rarely both) does not form in the normal way during pregnancy. Instead of having ...

Bilateral multicystic renal dysplasia means both kidneys did not form in the usual way while the baby was in the womb. The normal sponge-like kidney tissue is ...

Bilateral multicystic dysplastic kidney (bilateral MCDK) means both kidneys did not form normal working tissue before birth. Instead of healthy kidney tissue, ...

Microtia means a baby is born with an outer ear that is smaller, oddly shaped, or missing. It can be mild (a small ear) or severe (no visible ear, called ...

Microtia means a baby is born with a small or missing outer ear (pinna). It can affect one ear or both. Sometimes the ear canal is narrow or absent (aural ...

Bilateral microtia–hearing loss–cleft palate describes three problems present from birth. Microtia means the outer ear is small or poorly formed. When both ...

Bilateral microtia–deafness–cleft palate syndrome is a rare birth condition. “Bilateral” means both sides. “Microtia” means the outer ears are small, ...

Microcephaly, short stature, and polymicrogyria with seizures describes a child with three key features. First, the head size is small for age and sex ...

Diffuse polymicrogyria (PMG) is a brain-development problem in which the outer layer of the brain (the cortex) forms too many very small folds and the normal ...

Bilateral generalized polymicrogyria (BGP) is a brain development problem that starts before birth. In BGP, the outer layer of the brain (the cortex) forms too ...

Frontoparietal polymicrogyria (FPP) is a problem in how the brain’s outer layer (the cortex) formed before birth. “Polymicrogyria” means “many small folds.” In ...

Complex cortical dysplasia with other brain malformations 14A, often shortened to CDCBM14A, is a rare, inherited brain-development disorder. Before birth, the ...

Bilateral frontal polymicrogyria is a rare brain malformation that forms before birth. “Polymicrogyria” means “too many small folds” on the brain surface. In ...

Bilateral Acute Depigmentation of the Iris (BADI) is a rare eye condition where both irises suddenly lose their brown/blue/green color in patches or diffusely. ...

A submucous cleft palate is a hidden split or separation in the muscles of the soft palate that is covered by normal-looking mucosa (the lining skin). Because ...

Cleft of the uvula means the small soft tissue at the back of the mouth (the “uvula”) looks split into two tips. Many people have this with no trouble at all. ...

A disorder of written language involves a significant impairment in fluent word reading (i.e., reading decoding and sight word recognition), reading ...

A bifid palatine uvula means the little soft dangly part at the back of your throat (the uvula) looks split into two parts. Many people with a bifid uvula are ...

A bifid uvula means the little soft tissue that hangs at the back of your mouth—the uvula—is split into two parts or looks like it has a cleft. This split ...

Indentation clefting of the nose means there is a split, groove, or deep notch in the nose, often in the midline, that can range from a shallow dimple at the ...

A cleft nasal bridge means there is a visible split, groove, or gap along the top of the nose (the “bridge”) where the right and left sides did not fully join ...

A bifid nasal bridge means the bridge of the nose is split or divided down the middle. Instead of one smooth ridge, there is a midline groove or a true gap ...

A bifid nose means the nose looks “split” down the middle, as if the tip or the bridge has a groove that divides the nose into two parts. Doctors call this a ...

Bietti crystalline retinopathy (BCR)—also called Bietti crystalline corneoretinal dystrophy—is a rare, inherited eye disease. Tiny yellow-white crystals and ...

Bietti crystalline corneoretinal dystrophy is a rare, inherited eye disease. Tiny yellow-white crystals made of lipids (fats) collect in the retina and ...

Hypogonadism-short stature-coloboma-preaxial polydactyly syndrome is a very rare, inherited condition reported only in a small number of people. It affects ...

Biemond syndrome type 2 is the name given to a very rare condition reported in a small number of people. Doctors described a group of patients who had a ...

Tetrahydrobiopterin-deficient hyperphenylalaninemia due to PTS deficiency is a rare, inherited condition where the body cannot make enough tetrahydrobiopterin ...

Hyperphenylalaninemia due to 6-Pyruvoyltetrahydropterin Synthase (PTPS) Deficiency is a rare genetic problem where the body cannot make enough ...

bh4-deficient hyperphenylalaninemia type a happens when the body cannot make enough tetrahydrobiopterin (BH₄). BH₄ is a natural helper molecule (cofactor) that ...

6-Pyruvoyl-Tetrahydropterin Synthase (PTPS) Deficiency is a rare, inherited metabolic disorder. It belongs to a small group of conditions called ...

6-Pyruvoyl-Tetrahydrobiopterin Synthase (PTPS) Deficiency is a rare genetic condition that reduces the body’s supply of tetrahydrobiopterin (BH4). BH4 is a ...

BH4-deficient hyperphenylalaninemia A is a rare inherited condition in which the body cannot make enough of a helper molecule called tetrahydrobiopterin (BH4). ...

Benign congenital muscular dystrophies (CMDs)—genetic muscle disorders present from birth, such as LAMA2-related (merosin-deficient), collagen VI–related ...

Benign autosomal dominant myopathy is a hereditary muscle condition. Most people inherit one changed copy of a collagen-VI gene from a parent (autosomal ...

Bethlem myopathy is a rare, inherited muscle and connective-tissue condition. It causes slow-getting-worse (progressive) muscle weakness, early tight joints ...

Beta-alanine synthase deficiency is a very rare, inherited problem with breaking down the DNA/RNA building blocks called pyrimidines. Because one step in this ...

Beta-ureidopropionase deficiency is a very rare, inherited disorder of pyrimidine breakdown (the pathway the body uses to clear the building blocks of DNA and ...

Thrombocytopenia with X-linked recessive beta-thalassemia is a rare, inherited blood disorder that affects two blood cell lines at the same time: platelets ...

Beta-thalassemia–X-linked thrombocytopenia syndrome is a rare, inherited blood disorder that mainly affects boys and men. It happens when a gene on the X ...

Peroxisomal thiolase deficiency (historical label) was used for a suspected single-enzyme defect of the peroxisome pathway (enzyme: peroxisomal 3-ketoacyl-CoA ...

Mitochondrial acetoacetyl-coenzyme A thiolase deficiency is a rare, inherited problem with body chemistry. The body cannot properly break down the amino acid ...

Mitochondrial 2-methylacetoacetyl-CoA thiolase (ACAT1) deficiency—also called beta-ketothiolase (BKT) deficiency and sometimes described in older literature as ...

Deficiency of acetyl-coenzyme A acetyltransferase is a rare, inherited metabolic disorder. It happens when a specific enzyme inside the mitochondria does not ...

ACAT1 deficiency is a rare, inherited condition where the body cannot properly use the enzyme acetoacetyl-CoA thiolase. This enzyme helps the body break down ...

Alpha-methylacetoacetic aciduria is a rare, inherited metabolic disease. The body lacks enough activity of an enzyme called mitochondrial acetoacetyl-CoA ...

Alpha-methyl-acetoacetyl-CoA thiolase deficiency is a rare, inherited metabolic disorder. It is also called beta-ketothiolase (BKT) deficiency or ACAT1 ...

Alpha-methylacetoacetic aciduria is a rare, inherited metabolic disorder. The body cannot use a key enzyme (called mitochondrial acetoacetyl-CoA thiolase, also ...

Acetoacetyl-CoA thiolase deficiency is a rare, inherited metabolic disease. The body lacks enough activity of an enzyme called mitochondrial acetoacetyl-CoA ...

3-oxothiolase deficiency is a rare, inherited metabolic disorder. The body cannot properly break down the amino acid isoleucine. The body also cannot use ...

3-methyl-3-hydroxybutyric acidemia (the condition most newborn-screening programs and medical references call 2-methyl-3-hydroxybutyric acidemia, or HSD10 ...

2-methyl-3-hydroxybutyricacidemia is a rare inherited metabolic disease. Your body cannot properly break down the amino acid isoleucine and cannot use ketone ...

Beta-ketothiolase deficiency is a rare, inherited metabolic disease. It happens when a mitochondrial enzyme called acetoacetyl-CoA thiolase (also known as ...

Mannosidosis is a rare, inherited lysosomal storage disease. In healthy cells, lysosomes are the recycling centers that break down used-up molecules. In ...

Beta-mannosidase deficiency (often called beta-mannosidosis) is a very rare lysosomal storage disorder. The body is missing or has very low activity of an ...

Beta-D-mannosidosis is a very rare inherited disease. It happens when a person is born with changes (variants) in a gene called MANBA. This gene makes an ...

Cooley’s anemia is a genetic blood disease. It happens when the body cannot make enough beta-globin, a key building block of hemoglobin (the protein in red ...

Beta Thalassemia Syndrome is a group of inherited blood conditions where the body cannot make enough beta-globin, an essential protein chain that helps form ...

A thrombopathy is a problem with how platelets work. Platelets are tiny blood cells that help stop bleeding. In thrombopathy, the number of platelets may be ...

Hemorrhagiparous thrombocytic dystrophy is also known as bleeding-prone disorder involving platelets—either low platelet count (thrombocytopenia), inherited ...

Hemorrhagic dystrophic thrombocytopenia” is an old, descriptive name that doctors once used for a rare inherited bleeding disorder in which people have very ...

Giant platelet syndrome means the platelets in your blood are unusually large and the platelet count is low. Platelets are tiny blood cells that help stop ...

Giant platelet disorder means you are born with very large platelets and often fewer platelets than normal. Platelets help stop bleeding. When they are big ...

Bernard-Soulier syndrome is a rare bleeding disorder that you are born with. It happens because the platelets do not stick well to damaged blood vessels. ...

Bernard–Soulier thrombopathy is a rare, inherited bleeding disorder where platelets—the tiny cell fragments that plug holes in injured blood vessels—are both ...

Bernard–Soulier syndrome is a rare inherited bleeding disorder. In BSS, platelets are abnormally large and often fewer than normal. Doctors call this ...

Berk–Tabatznik syndrome (BTS) is an ultra-rare congenital condition described in only a few patients. The consistent features across reports are: short ...

Total lipodystrophy means the body loses almost all its fat everywhere. “Fat” here means adipose tissue, which stores energy and makes hormones like leptin and ...

Generalised congenital lipodystrophy (GCL) is a rare genetic condition present from birth. In GCL, the body has almost no fat tissue (adipose tissue) under the ...

“Brunzell syndrome” describes people who do not have normal body fat from birth. Because fat cells are missing, fat “spills” into organs like the liver and ...

Berardinelli-Seip syndrome is a rare genetic condition where the body is born with almost no fat tissue under the skin and around organs. Because fat cells are ...

Berardinelli-Seip congenital lipodystrophy (BSCL) is a rare genetic disease present from birth. In this condition, the body is missing almost all normal fat ...

Berardinelli-Seip syndrome is a rare genetic disease present from birth. The body is born with almost no fat tissue under the skin or around organs. Because ...

Berardinelli–Seip congenital lipodystrophy is a rare genetic disease present from birth. Babies and children with this condition have almost no body fat under ...

B-cell expansion with nuclear factor kappa-light-chain enhancer of activated B cells and T-cell anergy disease is a rare, inherited immune system disorder. ...

B-cell Expansion with NF-κB and T-cell Anergy is a rare, inherited immune disorder caused by gain-of-function (GOF) mutations in the gene CARD11. CARD11 sits ...

BENTA disease is a rare genetic problem of the immune system. “BENTA” stands for B-cell Expansion with NF-κB and T-cell Anergy. In simple words, people with ...

Perinatal lethal bent bone dysplasia is a very rare genetic bone disorder. It affects a baby before birth. The bones do not form in a normal way. The long ...

FGFR2-related bent bone dysplasia is a very rare genetic bone disorder. It starts before birth. A single gene called FGFR2 has a harmful change (a mutation). ...

Bent bone dysplasia syndrome 1 (BBDS1) is a very rare, usually lethal skeletal (bone) disorder that begins before birth. It is caused by disease-causing ...

Benign Samaritan congenital myopathy is a very rare, inherited muscle condition. Babies are born very “floppy” (low muscle tone) and can have trouble ...

Benign Recurrent Intrahepatic Cholestasis type 2 (BRIC2) is a rare, inherited liver condition. People with BRIC2 have repeated “attacks” (episodes) in which ...

Benign recurrent intrahepatic cholestasis (BRIC) caused by ATP8B1 mutation is a rare, inherited liver disorder. “Benign” here means it usually does not cause ...

ATP8B1 Benign Recurrent Intrahepatic Cholestasis (BRIC1) is a rare, inherited liver condition caused by changes in the ATP8B1 gene. This gene helps keep the ...

Benign recurrent intrahepatic cholestasis type 1 is a rare, inherited liver condition. “Benign” means it usually does not cause permanent liver scarring. ...

Summerskill–Walshe–Tygstrup syndrome is a rare, inherited liver condition. People with this condition have repeated attacks of cholestasis, which means the ...

Benign recurrent cholestasis (BRC/BRIC) is a rare liver condition where bile flow from the liver slows or stops for weeks to months, then gets better by itself ...

Benign familial recurrent cholestasis (BRIC) is a rare, inherited liver condition. “Benign” means it does not usually lead to permanent liver damage. ...

Benign recurrent intrahepatic cholestasis (BRIC) is a rare, inherited liver condition. It causes repeated “attacks” when bile cannot flow out of liver cells ...

Benign partial epilepsy with secondarily generalized seizures in infancy (now grouped by the International League Against Epilepsy under self-limited infantile ...

Benign Partial Epilepsy of Infancy with Complex Partial Seizures—historically “benign familial (or non-familial) infantile seizures,” sometimes described as ...

Benign paroxysmal torticollis of infancy is a short-lasting, repeatable head-tilt problem that starts in babies. During an “attack,” a baby’s head tilts to one ...

Ouvrier–Billson syndrome is a rare neuro-ophthalmic condition in babies and young children. During “spells,” the child’s eyes hold a fixed upward gaze, often ...

Neuroocular syndrome 2, paroxysmal type (NOC2)”—a disorder best known for recurrent upward eye deviation (or vertical nystagmus) with abnormal head posturing ...

Benign paroxysmal tonic upgaze of childhood with ataxia is a rare, early-life movement and eye-movement condition. “Paroxysmal” means it comes in bursts or ...

Self-limited familial neonatal epilepsy (SLFNE) is a genetic epilepsy that starts in the first days of life in otherwise healthy newborns. Seizures often ...

Convulsions benign familial neonatal dominant form is the modern name for what used to be called benign familial neonatal convulsions. It is a genetic epilepsy ...

Benign neonatal familial convulsions (BNFC) is a rare, inherited epilepsy syndrome. Seizures begin in otherwise healthy newborns, most often between day 2 and ...

Benign familial neonatal seizures is a genetic epilepsy syndrome that starts in the first week of life in otherwise healthy newborns. Seizures are brief, can ...

Benign familial neonatal epilepsy is a genetic epilepsy syndrome that starts in the first week of life in otherwise healthy newborns. Babies have short ...

Benign familial neonatal convulsions (BFNC) are brief seizures that start in the first days of life in otherwise healthy newborns, often occurring in clusters, ...

Benign familial convulsions are brief seizures in babies who are otherwise well. “Benign” (now replaced by the term self-limited) means seizures stop by ...

Benign familial neonatal seizures (BFNS) is a rare, inherited epilepsy syndrome that starts in the first days of life, usually between day 2 and day 8 after ...

Self-limited (familial) neonatal epilepsy (SeLNE) is a genetic epilepsy syndrome that runs in families in an autosomal dominant pattern. “Autosomal dominant” ...

Benign neonatal seizures are seizures that start in the first days of life in otherwise healthy newborns and then stop on their own over the next weeks or ...

Scarring pemphigoid is an autoimmune blistering disease. Your immune system mistakenly attacks the “basement membrane zone,” which is the anchoring layer that ...

Mucous membrane pemphigoid (MMP) is a rare, long-lasting autoimmune blistering disease. Your immune system makes antibodies that attack the “basement membrane ...

Mucosynechial pemphigoid (more commonly called mucous membrane pemphigoid, MMP; also known as cicatricial pemphigoid and ocular cicatricial pemphigoid). It is ...

Mucosynechia atrophic bullous dermatitis that phrase is considered an old synonym for mucous membrane pemphigoid (MMP), also called cicatricial pemphigoid—a ...

Mucosal pemphigoid—also called mucous membrane pemphigoid (MMP)—is a rare autoimmune disease. “Autoimmune” means the immune system mistakenly attacks the ...

Cicatricial pemphigoid is an autoimmune disease. “Autoimmune” means your immune system attacks your own body by mistake. In this disease, the attack happens at ...