A genetic defect causes a rare form of Alzheimer’s disease in the early 1940s

from Melanie Hoffman | September 08, 2021, 4:13 am

Alzheimer’s disease is a disease that usually affects the elderly in particular. Scientists have now discovered a very rare and dangerous form of the disease in several members of the same family from Sweden, which develops rapidly and begins as early as the 1940s.

A family history of Alzheimer’s disease

Seven years ago, scientists at Uppsala University discovered the story of the suffering of the Swedish family by chance. At that time, two brothers were examined in the university clinic. They experienced amnesia, had problems with their sense of direction and generally had a feeling that they were no longer mentally fit. The third victim was a cousin who had similar symptoms. He could no longer speak full sentences clearly and even solve simple arithmetic problems. All three were diagnosed with Alzheimer’s disease, or because of their young age, “early Alzheimer’s dementia.” As if that weren’t enough, it turns out that the two brothers’ father had also been treated for Alzheimer’s in the clinic 20 years ago. He was also in his early forties at the time.¹

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DNA defect

Together with neuroscientists, structural and molecular biologists, and imaging experts, the scientists have come to the bottom of the rare form of Alzheimer’s disease. In doing so, they discovered a new mutation in the APP gene. This speeds up sedimentation amyloid beta proteins, which is considered a sign of dementia and Alzheimer’s disease. The researchers named the rare form of Alzheimer’s disease that appeared in this way “Uppsala deletion” – after the only family so far in which this specific DNA bug can be detected. The mutation appears to lead to dementia at an early age and is passed on from generation to generation.²

A new mutation has been identified in the APP gene

Other forms of Alzheimer’s disease have also been linked to changes in the APP gene. Researchers around the world were previously able to identify more than 50 different mutations. With the help of genetic analysis and more biological and chemical tests, study author Dr. Maria Bagno de la Vega and her team now identify this new APP genetic defect as the cause of Alzheimer’s disease. What distinguishes the mutation discovered in Uppsala: it directly deletes six amino acids from the amino acid chain. The result is a devastating deposition of the dementia protein in the entire brain and the early onset of Alzheimer’s disease.

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The effect of APP mutations

With the discovery of this new mutation in the APP gene, scientists hope to be able to further elucidate the mechanisms in the body that lead to Alzheimer’s disease. Because dementia still leaves many questions unanswered. There is also no possibility of treatment in sight. So each new discovery is significant and represents a step forward in Alzheimer’s disease research.

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