Study IDs Gene for Late-Onset Alzheimer's

29 may 2008-- A gene that plays a role in Alzheimer's disease in two large families in which many siblings suffer from the neurodegenerative condition has been identified by U.S. researchers.
Identification of this gene -- TRPC4AP on chromosome 20 -- opens a new line of research that may help improve understanding of what causes Alzheimer's disease.
TRPC4AP is involved in calcium regulation. It's known that when calcium levels aren't carefully controlled, cells can die, leading to the onset of disease.
In this study, researchers at the Medical College of Georgia and the VA Medical Center in Augusta focused on two large families with a history of late-onset Alzheimer's disease who were enrolled in a DNA bank. Both families had 15 siblings, five of whom had Alzheimer's. Analysis of blood samples revealed that all the patients in both families had the same pattern of single nucleotide polymorphisms (SNPs), which are single base changes in gene structure found throughout DNA.
When they analyzed samples from other Alzheimer's patients in the DNA bank, the researchers found that 36 percent had the same pattern of SNPs as the patients in the two families.
The study was published in the current issue of the American Journal of Medical Genetics Part B: Neuropsychiatric Genetics.
"The use of extended pedigrees is vital for genetic studies. The next step will be to identify the exact mutation in this gene which is causing the disease. The DNA is currently being sequenced to find this mutation," study author Dr. Shirley Poduslo said in a prepared statement.
"The long-term significance will be to understand the mechanism of the disease so that more effective drugs can be designed to slow the progression of the disease, delay the onset, identify patients early in the disease course and, hopefully, someday to keep this dreadful disease from occurring," Poduslo said.