Discovery of New Biomarker in Blood Could Lead to Early Test for Alzheimer's Disease

A study from the University of California, San Diego in Current Biology learned that high blood levels of RNA produced by the PHGDH gene could function as a biomarker for early detection of Alzheimer's disease, reports EurekAlert . This research could lead to the development of a blood test to identify persons who will develop the disease years before they become symptomatic. The PHGDH gene generates RNA and proteins crucial to brain development and function in infants, children, and adolescents. As people age, PHGDH usually produces less, and the new study suggests that overproduction of extracellular RNA (exRNA) by the gene in older adults could signal nascent Alzheimer's. The researchers determined this using a method called SILVER-SEQ, which is sensitive enough to sequence tens of thousands of exRNAs in less than a single drop of blood. SILVER-SEQ analyzed the exRNA profiles in blood samples of 35 people 70 years and older who were tracked up to 15 years before death. Included were 15 with Alzheimer's; 11 "converters," or subjects who were initially healthy then later developed Alzheimer's; and nine healthy controls. A steep increase in PHGDH exRNA production was observed among all converters about two years before they were clinically diagnosed with Alzheimer's, and PHGDH exRNA levels were on average higher in those with Alzheimer's.