NEW YORK, Jan 27 (Reuters Health) -- Carrying certain genes increases the
risk of repeat episodes of stroke due to bleeding into the brain, report Harvard
researchers.
The finding may lead to new ways to identify patients at risk for another
stroke, and perhaps to new ways to prevent the problem, according to the study
authors. Their report is published in the January 27th issue of The New England
Journal of Medicine.
The genes in question, variants of the apolipoprotein E gene, have been
previously implicated in lipid disorders and Alzheimer's disease. These genes
carry information for a protein involved in fat metabolism.
"While the gene type cannot help us predict what patients will have
strokes, it does help us to identify patients who might bleed again and to study
treatments that could prevent those recurrent strokes," Dr. Steven M. Greenberg
from Massachusetts General Hospital in Boston, Massachusetts told Reuters
Health.
Apolipoprotein E plays a key role in the development of a condition called
cerebral amyloid angiopathy, a major cause of brain hemorrhage in the elderly.
The gene for apolipoprotein E comes in three forms -- epsilon 2 (e2), epsilon 3
(e3, the most common form), and epsilon 4 (e4) -- and everyone has two of these
genes in any combination, the authors explain.
Among 18 patients who experienced repeated strokes, 14 had at least one e2
or e4 form of the gene, the results indicate, and they faced a 28% chance of
having another stroke over a period of 2 years. In contrast, four patients had
two e3 gene forms, and their risk of another stroke was only 10%.
Patients who had experienced a stroke before the study had nearly seven
times the risk of another stroke (compared to those without an earlier stroke),
but age, sex, and other diseases (hypertension, dementia, or diabetes) were not
linked to repeat strokes, the investigators note.
The risk of repeat stroke was highest among patients who had both e2 and
e4 forms of the apolipoprotein E gene, the researchers report, and those
patients had repeat strokes earlier than other patients.
"This finding suggests that e2 and e4 (gene forms) might identify the
patients in whom cerebral amyloid angiopathy is sufficiently severe and
widespread to cause early recurrence," Greenberg and colleagues conclude.
"We don't test every elderly person," Greenberg said, "because the gene
type doesn't predict whether a first stroke will occur. But we might test other
elderly patients for whom we're considering (blood-thinning drugs) like aspirin
or warfarin. You might decide not to use such treatments in patients with e2 or
e4 (gene forms)" because of their increased risk of bleeding into the brain.
