Levene died in 1940, before the true significance of DNA became clear. Levene is known for his tetranucleotide hypothesis (formulated around 1910) which first proposed that DNA was made up of equal amounts of adenine, guanine, cytosine, and thymine.
Alzheimer's is not just a disease of old age. Younger-onset (also known as early-onset) Alzheimer's affects people younger than age 65.Up to 5 percent of the more than 5 million Americans with Alzheimerâs have younger-onset.eople who have early onset Alzheimer's may be in any stage of dementia â early stage, middle stage or late stage. The disease affects each person differently and symptoms will vary. If you are experiencing memory problems: 1  Have a comprehensive medical evaluation with a doctor who specializes in Alzheimer's disease.
According to the Alzheimer's Association, Alzheimerâs disease most commonly affects older adults, but it can also affect people in their 30s or 40s. When Alzheimerâs disease occurs in someone under the age of 65, it is known as early-onset (or younger-onset) Alzheimerâs disease.ypes of early-onset Alzheimerâs disease. Most types of early-onset Alzheimerâs disease are the same, but there are a few small distinctions: Common Alzheimerâs disease. The majority of people with early-onset Alzheimerâs disease have the common form of Alzheimerâs disease.