The hallmark of FAD is the accumulation of the Amyloid Beta 42 peptide (a short chain of amino acids) in unusually high concentrations within the brain. In a healthy brain, Amyloid Beta-42 (Aß42) and a similar peptide, Amyloid Beta-40 (Aß40), are found in a ratio of about 1 to 9. In a brain affected by FAD, this ratio is much higher. The two peptides are nearly identical: Aß40 is a chain of 40 amino acids in length; Aß42 is 42 amino acids in length. However, Aß42 is much more toxic to neurons and plays a critical role in memory failure.
“The mutations that cause FAD lead to an increased ratio of Aß42 over Aß40,” said Wang, an associate professor of biological sciences within the School of Science, director of the biochemistry and biophysics graduate program, and member of the Rensselaer Center for Biotechnology and Interdisciplinary Studies, who co-wrote the paper with Wen Chen, who recently earned his doctorate at Rensselaer. “That’s the biochemistry, and that has been observed by many people. But the question we asked is: how? How do the mutations lead to this increased ratio?”
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