Researchers describe novel gene mutations associated with Alzheimer disease

Three mutations in genes associated with Alzheimer disease (AD) are described by researchers in the November issue of The Archives of Neurology, one of the JAMA/Archives journals.

Alzheimer disease (AD) is a complex neurodegenerative disorder often affecting the elderly and characterized by gradual loss of memory and cognitive decline, according to the article. AD is often accompanied by a buildup of certain proteins or plaques in the brain. Since 1991, the results of genetic studies have led to the identification of gene mutations and variations that can either cause AD or increase the risk for developing the disease. Familial Alzheimer disease (FAD), which accounts for approximately 5 percent to 10 percent of all cases of AD, has been found to influenced by mutations on genes coding for presenilin. Presenilin is a protein that has been associated with plaque formation.

Sandro Sorbi, M.D., of the University of Florence, Italy and colleagues obtained DNA samples from 45 individuals with FAD. Participants were outpatients from the neurology departments at the Universities of Florence and Parma, and the Santa Maria Nuova Hospital in Reggio Emilia, Italy. The authors conducted genetic studies to screen certain genes for mutations associated with FAD.

The researchers identified several families carrying presenilin mutations. They found one presenilin gene mutation associated with variable age of onset AD (from 35 to 85 years old) in one family, and found two new presenilin gene mutations associated with early onset AD at age 49 to 54 years old in two other unrelated Italian families.

“In conclusion, results of this study confirm and extend the concept that the clinical manifestation of PS1 and PS2 [presenilin genes] mutations may be typical for AD and more similar to other dementias,” write the authors.

“In addition, the identification of new mutations is important, particularly for developing diagnostic testing programs based on the frequency of mutations in specific populations and for further enlarging out understanding of the great variability of [familial Alzheimer disease],” the researchers write.

(Arch Neurol. 2003;60:1541-1544. Available post embargo at archneurol.com)

Editor’s Note: This study was supported by a grant from the Ministero dell’Universita e della Ricerca Scientifica e Tecnologica, Rome, Italy; a grant from the Telethon Fondazione Onlus, Rome; and grants from the European Union.

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