Dr Turner, 66, from Bath, had a progressive and incurable degenerative disease called supranuclear palsy.

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Mark Smolinski, in charge of predicting and preventing disease and drought, knew Brilliant while he was at the Center for Disease Control, and more recently ran research in biological weapons programs at Ted Turner's Nuclear Threat Initiative.

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Turner suffers from ALS, or amyotrophic lateral sclerosis, also known as Lou Gehrig's disease.

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Even if amyloid does trigger the disease process, by the time symptoms become obvious "the disease becomes independent of amyloid so it progresses even if the amyloid is removed, " says Scott Turner of Georgetown University.

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