Biotin-thiamine-responsive basal ganglia disease (BTBGD) | |
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Other names | BTRBGD, [1] Biotin-responsive basal ganglia disease (BBGD), [2] Thiamine metabolism dysfunction syndrome 2 (biotin or thiamine-responsive type) (THMD2), [3] Thiamine-responsive encephalopathy, Thiamine transporter-2 deficiency [4] |
Specialty | Neurometabolic disorders, neurology, internal medicine |
Symptoms | Subacute encephalopathy; dystonia; spasticity; seizures; dysphagia; ataxia; dysarthria; etc. [5] |
Usual onset | Childhood (ages 3-10) [4] |
Duration | Lifelong |
Causes | Family history (inherited) [2] |
Risk factors | Febrile illness; stress; trauma [5] |
Diagnostic method | Based on symptoms, family history, brain imaging, genetic testing [5] |
Management | |management= Prevention of symptoms, avoiding stressors, and routine surveillance [5] |
Medication | Administering biotin and thiamine; symptomatic treatments [5] |
Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare disease that affects the nervous system, particularly the basal ganglia in the brain. [4] It is a treatable neurometabolic disorder with autosomal recessive inheritance. [2] [1] First described in 1998 [6] and then genetically distinguished in 2005, [7] the disease is characterized by progressive brain damage that, if left untreated, can lead to coma and/or death. [1] Commonly observed in individuals with BTBGD is recurring subacute encephalopathy along with confusion, seizures, and disordered movement (hypokinesia). [8]
BTBGD has several alternate names, including:
The onset of signs and symptoms can occur at any age but is most common in childhood between the ages of 3 and 10. [4] Less commonly, it may present in early infancy or adulthood. The neurological symptoms usually present as episodes of increasing severity. A less common exhibition of BTBGD involves persistent symptoms, rather than recurrent episodes. [4] In these cases, fewer symptoms are usually present, with their severity slowly increasing over time.[ citation needed ]
Recurrent subacute encephalopathy is the most commonly observed symptom, followed by dystonia, both of which are nearly always present. Additional observed symptoms include spasticity or cogwheel rigidity, seizures, difficulty swallowing (dysphagia), ataxia, slurred speech (dysarthria), ophthalmoplegia, opisthotonus, facial palsy, confusion, hyperreflexia, Babinski responses, and ankle clonus. [5]
In early infancy, the presentation of BTBGD is considered as Leigh-like syndrome or atypical infantile spasms. [5] It is characterized by acute encephalopathy, vomiting, metabolic acidosis (specifically lactic acidosis), and poor feeding during the first 3 months of life. [1] [5]
Presentation of late-onset BTBGD is considered a Wernicke-like encephalopathy. [1] [5] It is characterized by ataxia, ophthalmoplegia, double vision (diplopia), rapid and uncontrollable eye movement (nystagmus), status seizures, and droopy eyelid (ptosis). The onset of signs and symptoms for adulthood presentation occurs during or after the second decade of life.[ citation needed ]
SLC19A3 gene mutations cause BTBGD. [4] SLC19A3 is a gene on chromosome 2q36.3 that encodes the protein thiamine transporter 2. [4] [5] Thiamine transporter 2 moves thiamine (vitamin B1) into cells, which is essential for nervous system functioning. Mutations of the gene encoding this protein (SLC19A3) are likely to impair the functioning of this protein and inhibit the transportation and absorption of thiamine.[ citation needed ]
The role of biotin in BTBGD is unclear. [4]
Episodes of symptoms can be triggered by several things: [5]
BTBGD can be diagnosed based on brain imaging and confirmed with genetic testing. [9] Additional diagnostic tools include laboratory testing of biological fluids and reviewing autosomal recessive inheritance in the family history.[ citation needed ]
The MRI of individuals with BTBGD may reveal lesions on the basal ganglia and central bilateral necrosis in the caudate nucleus and putamen. [7] [10] Vasogenic edema is also characteristic of BTBGD. [5] Additional MRI findings include high T2 signal intensity with possible swelling in basal ganglia, and abnormal diffuse involvement of the subcortical white matter, cortical, and infratentorial brain. [5] [11] Involvement in the thalami, brain stem, and cerebellum may also be observed. [11]
Molecular genetic tests that can be performed for BTBGD include: [5]
Other disorders that present similar clinical findings include: [5]
Family members of individuals with BTBGD may be tested regardless of symptoms. [12] Family members may be affected by the disease, may be asymptomatic carriers of the mutation, or may be completely unaffected. [5] Genetic testing of family members allows for the identification of subtle symptoms, asymptomatic carriers, and increased-risk individuals, which allows for early treatment as needed.[ citation needed ]
Treatment of BTBGD is done to manage specific symptoms and concerns. [5] If left untreated, the disease can be fatal. Treatment may vary by symptom, though it is common to administer thiamine (up to 40 mg/kg/day) and sometimes biotin (5-10 mg/kg/day) orally. This treatment is specifically used to address neurological symptoms and can reverse these symptoms if taken early enough. Biotin and thiamine oral therapy must continue throughout the entirety of the individual's life. [5] Other symptomatic treatments include anti-seizure medication to treat seizures and trihexyphenidyl or L-dopa to treat dystonia. Rehab and therapy are used for developmental and social concerns.[ citation needed ]
Management of BTBGD includes prevention of symptoms and routine surveillance. [5] Avoiding stressors is essential in managing BTBGD since stress and trauma can trigger episodes. Fevers are also triggers, so fever control is important. Other triggers that should be avoided include infections and excessive exercise. Routine surveillance should include evaluation of the individual's nervous system, education and development, and any other relevant areas.[ citation needed ]
The prevalence of BTBGD is unknown. [4] Of the reported cases, it is predominately observed in individuals from Arab populations.
Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by mild-to-moderate intellectual disability. The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled. Physical features may include a long and narrow face, large ears, flexible fingers, and large testicles. About a third of those affected have features of autism such as problems with social interactions and delayed speech. Hyperactivity is common, and seizures occur in about 10%. Males are usually more affected than females.
Encephalopathy means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of overall brain dysfunction; this syndrome has many possible organic and inorganic causes.
Wernicke encephalopathy (WE), also Wernicke's encephalopathy, or wet brain is the presence of neurological symptoms caused by biochemical lesions of the central nervous system after exhaustion of B-vitamin reserves, in particular thiamine (vitamin B1). The condition is part of a larger group of thiamine deficiency disorders that includes beriberi, in all its forms, and alcoholic Korsakoff syndrome. When it occurs simultaneously with alcoholic Korsakoff syndrome it is known as Wernicke–Korsakoff syndrome.
Leigh syndrome is an inherited neurometabolic disorder that affects the central nervous system. It is named after Archibald Denis Leigh, a British neuropsychiatrist who first described the condition in 1951. Normal levels of thiamine, thiamine monophosphate, and thiamine diphosphate are commonly found, but there is a reduced or absent level of thiamine triphosphate. This is thought to be caused by a blockage in the enzyme thiamine-diphosphate kinase, and therefore treatment in some patients would be to take thiamine triphosphate daily. While the majority of patients typically exhibit symptoms between the ages of 3 and 12 months, instances of adult onset have also been documented.
Primary familial brain calcification (PFBC), also known as familial idiopathic basal ganglia calcification (FIBGC) and Fahr's disease, is a rare, genetically dominant or recessive, inherited neurological disorder characterized by abnormal deposits of calcium in areas of the brain that control movement. Through the use of CT scans, calcifications are seen primarily in the basal ganglia and in other areas such as the cerebral cortex.
Isovaleric acidemia is a rare autosomal recessive metabolic disorder which disrupts or prevents normal metabolism of the branched-chain amino acid leucine. It is a classical type of organic acidemia.
Maple syrup urine disease (MSUD) is a rare, inherited metabolic disorder that affects the body’s ability to metabolize amino acids due to a deficiency in the activity of the branched-chain alpha-ketoacid dehydrogenase (BCKAD) complex. It particularly affects the metabolism of amino acids- leucine, isoleucine, and valine. With MSUD, the body is not able to properly break down these amino acids, therefore leading to the amino acids to build up in urine and become toxic. The condition gets its name from the distinctive sweet odor of affected infants' urine and earwax due to the buildup of these amino acids.
Pantothenate kinase-associated neurodegeneration (PKAN), formerly called Hallervorden–Spatz syndrome, is a genetic degenerative disease of the brain that can lead to parkinsonism, dystonia, dementia, and ultimately death. Neurodegeneration in PKAN is accompanied by an excess of iron that progressively builds up in the brain.
MELAS is one of the family of mitochondrial diseases, which also include MIDD, MERRF syndrome, and Leber's hereditary optic neuropathy. It was first characterized under this name in 1984. A feature of these diseases is that they are caused by defects in the mitochondrial genome which is inherited purely from the female parent. The most common MELAS mutation is mitochondrial mutation, mtDNA, referred to as m.3243A>G.
Thiamine deficiency is a medical condition of low levels of thiamine (vitamin B1). A severe and chronic form is known as beriberi. The name beriberi was possibly borrowed in the 18th century from the Sinhalese phrase බැරි බැරි (bæri bæri, “I cannot, I cannot”), owing to the weakness caused by the condition. The two main types in adults are wet beriberi and dry beriberi. Wet beriberi affects the cardiovascular system, resulting in a fast heart rate, shortness of breath, and leg swelling. Dry beriberi affects the nervous system, resulting in numbness of the hands and feet, confusion, trouble moving the legs, and pain. A form with loss of appetite and constipation may also occur. Another type, acute beriberi, found mostly in babies, presents with loss of appetite, vomiting, lactic acidosis, changes in heart rate, and enlargement of the heart.
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GLUT1 deficiency syndrome, also known as GLUT1-DS, De Vivo disease or Glucose transporter type 1 deficiency syndrome, is an autosomal dominant genetic metabolic disorder associated with a deficiency of GLUT1, the protein that transports glucose across the blood brain barrier. Glucose Transporter Type 1 Deficiency Syndrome has an estimated birth incidence of 1 in 90,000 to 1 in 24,300. This birth incidence translates to an estimated prevalence of 3,000 to 7,000 in the U.S.
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