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ABri amyloidosis(FBD)

MedGen UID:
Concept ID:
Disease or Syndrome
Synonyms: Cerebral amyloid angiopathy, British type; CEREBRAL AMYLOID ANGIOPATHY, ITM2B-RELATED, 1; Dementia familial British; FBD; Presenile dementia with spastic ataxia
SNOMED CT: Familial dementia British type (783161005); ABri amyloidosis (783161005); Familial British dementia with amyloid angiopathy (783161005)
Modes of inheritance:
Autosomal dominant inheritance
MedGen UID:
Concept ID:
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.
Gene (location): ITM2B (13q14.2)
Monarch Initiative: MONDO:0008306
OMIM®: 176500
Orphanet: ORPHA97345


ITM2B-related cerebral amyloid angiopathy-1, also known as familial British dementia (FBD), is an autosomal dominant neurodegenerative disorder characterized by progressive dementia, spasticity, and cerebellar ataxia, with onset at around the fifth decade of life. Cerebral amyloid angiopathy, nonneuritic and perivascular plaques, and neurofibrillary tangles are the predominant pathological lesions (summary by Vidal et al., 1999). [from OMIM]

Clinical features

From HPO
MedGen UID:
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Sign or Symptom
A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.
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Concept ID:
Sign or Symptom
An unintentional, oscillating to-and-fro muscle movement about a joint axis.
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Mental or Behavioral Dysfunction
A loss of global cognitive ability of sufficient amount to interfere with normal social or occupational function. Dementia represents a loss of previously present cognitive abilities, generally in adults, and can affect memory, thinking, language, judgment, and behavior.
Progressive neurologic deterioration
MedGen UID:
Concept ID:
MedGen UID:
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A condition in which there is increased muscle tone so that arms or legs, for example, are stiff and difficult to move.
MedGen UID:
Concept ID:
Sign or Symptom
Continuous involuntary sustained muscle contraction. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity.
Cerebral amyloid angiopathy
MedGen UID:
Concept ID:
Disease or Syndrome
Hereditary cerebral amyloid angiopathy is a condition characterized by an abnormal buildup of protein clumps called amyloid deposits in the blood vessels in the brain, causing vascular disease (angiopathy). People with hereditary cerebral amyloid angiopathy often have progressive loss of intellectual function (dementia), stroke, and other neurological problems starting in mid-adulthood. Due to neurological decline, this condition is typically fatal in one's sixties, although there is variation depending on the severity of the signs and symptoms. Most affected individuals die within a decade after signs and symptoms first appear, although some people with the disease have survived longer.\n\nThere are many different types of hereditary cerebral amyloid angiopathy. The different types are distinguished by their genetic cause, which determines whether areas of the brain other than blood vessels are affected, and the signs and symptoms that occur. The various types of hereditary cerebral amyloid angiopathy are named after the regions where they were first diagnosed.\n\nThe Dutch type of hereditary cerebral amyloid angiopathy is the most common form. Stroke is frequently the first sign of the Dutch type and is fatal in about one third of people who have this condition. Survivors often develop dementia and have recurrent strokes. About half of individuals with the Dutch type who have one or more strokes will have recurrent seizures (epilepsy).\n\nPeople with the Flemish and Italian types of hereditary cerebral amyloid angiopathy are prone to recurrent strokes and dementia. Individuals with the Piedmont type may have one or more strokes and typically experience impaired movements, numbness or tingling (paresthesias), confusion, or dementia.\n\nTwo types of hereditary cerebral amyloid angiopathy, known as familial British dementia and familial Danish dementia, are characterized by dementia and movement problems. Strokes are uncommon in these types. People with the Danish type also have clouding of the lens of the eyes (cataracts) and deafness.\n\nThe first sign of the Icelandic type of hereditary cerebral amyloid angiopathy is typically a stroke followed by dementia. Strokes associated with the Icelandic type usually occur earlier than the other types, with individuals typically experiencing their first stroke in their twenties or thirties.\n\nStrokes are rare in people with the Arctic type of hereditary cerebral amyloid angiopathy, in which the first sign is usually memory loss that then progresses to severe dementia. Strokes are also uncommon in individuals with the Iowa type. This type is characterized by memory loss, problems with vocabulary and the production of speech, personality changes, and involuntary muscle twitches (myoclonus).

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVABri amyloidosis

Recent clinical studies

Clinical prediction guides

Pickford F, Coomaraswamy J, Jucker M, McGowan E
Brain Pathol 2006 Jan;16(1):80-5. doi: 10.1111/j.1750-3639.2006.tb00564.x. PMID: 16612985Free PMC Article

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