Early-onset, autosomal dominant Alzheimer disease

Alternate names

EOFAD; Early-onset familial autosomal dominant Alzheimer disease; Early-onset autosomal dominant Alzheimer disease; Familial Alzheimer disease

Summary

Early-onset, autosomal dominant Alzheimer disease is a form of Alzheimer disease (AD) that develops before the age of 65. It is diagnosed in families that have more than one member with AD (usually multiple persons in more than one generation) in which the age of onset is consistently before age 60 and often between the ages of 30 and 60 years. In general, AD is a degenerative disease of the brain that causes gradual loss of memory, judgement, and the ability to function socially.

Types

There are three subtypes of early-onset familial AD which are each associated with changes (mutations) in unique genes:

Cause

• Alzheimer disease, type 1 is caused by mutations in the APP gene
• Alzheimer disease, type 3 is caused by mutations in the PSEN1 gene
• Alzheimer disease, type 4 is caused by mutations in the PSEN2 gene.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

Early-onset, autosomal dominant Alzheimer disease is inherited in an autosomal dominant manner. This means that to be affected, a person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with this condition has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

Signs and symptoms

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Abnormal social behavior(Abnormal social behaviour)
• Agitation
• Cerebral cortical atrophy(Decrease in size of the outer layer of the brain due to loss of brain cells)
• Confusion(Disorientation)
• Deposits immunoreactive to beta-amyloid protein
• Hallucinations(Hallucination)
• Hypertonia
• Language impairment
• Memory impairment(Forgetfulness)
• Myoclonus
• Neurofibrillary tangles
• Parkinsonism
• Seizure

30%-79% of people have these symptoms

• Disinhibition

5%-29% of people have these symptoms

• Abnormality of vision(Abnormality of sight)
• Aphasia(Difficulty finding words)
• Ataxia
• Dysgraphia
• Finger agnosia
• Intellectual disability(Mental deficiency)
• Oculomotor apraxia
• Semantic dementia

Diagnosis

• Early-onset, autosomal dominant Alzheimer disease is diagnosed in families that have more than one member with AD in which the age of onset is before age 60 to 65 years.
• Genetic testing and identification of a mutation in one of the implicated genes (PSEN1, APP, or PSEN2) in an affected family member can assist in confirming the diagnosis.
• Not all families with early-onset, autosomal dominant Alzheimer disease are found to have mutations in one of the three known genes; therefore there may be other genes involved that have not yet been reported.

Treatment

Unfortunately, there is no cure for Alzheimer disease in general; however, there are medications that may assist in temporarily helping with memory and thinking problems, such as Exelon, Galantamine, and Aricept. Physical and occupational therapy can be helpful in managing problems with walking and activities of daily living. Depression and seizures may be treated with appropriate medications.

NIH genetic and rare disease info

• NIH info on Early-onset, autosomal dominant Alzheimer disease

Early-onset, autosomal dominant Alzheimer disease is a rare disease.

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