Familial Alzheimer's disease (FAD), a form of early-onset Alzheimer's, is an inherited, rare form of the disease that affects less than 5 percent of Alzheimer's disease patients. It is entirely passed down through genetics, inherited from parent to child. Symptoms appear at a much earlier age than other types of Alzheimer's. Individuals with FAD share symptomology with later onset; memory loss, confusion, trouble with once familiar tasks, however onset of these symptoms can begin as early as the 30's or 40's.

Familial Alzheimer's disease is indicated by a mutation in one of three chromosomes: 21, 14, and 1. The mutation causes the formation of abnormal proteins that generate harmful forms of amyloid plaques.

After a loved one is diagnosed with Alzheimer's, a common question among family members concerns the heritability of the disease. Current research reports that FAD is definitively genetically inherited; meaning a parent has been diagnosed with the disease, and children each have a 50% chance of inheriting it.

Scientists who study the genetics of Alzheimer’s distinguish between “familial Alzheimer’s disease,” which runs in families, and “sporadic Alzheimer’s disease,” where no obvious inheritance pattern is seen. Most Alzheimer's patients experience the sporadic form known as late onset Alzheimer's. From what researchers know, this form of the disease is not a hereditary disease, but instead has genetic, lifestyle and environmenal factors.

The majority of Alzheimer’s disease cases are late-onset, usually developing after age 65. It is important to reiterate: Late-onset Alzheimer’s disease has no known cause and from what researchers know, this form of this disease shows no obvious inheritance pattern.

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Genetic testing is available for Familial Alzheimer's disease, however it is important to consider that, like late onset AD, there is no cure. The emotional toll of knowing you carry a genetic mutation is a heavy one. While research for a cure continues, arm yourself with proper future planning and healthy lifestyle choices.