Elevated γ-glutamyltransferase and erythrocyte sedimentation rate in ischemic stroke in discordant monozygotic twin study

Dear editor,

In order to investigate potential genetic causes for stroke, we carried out a detailed comparison of blood chemistries of a pair of 62–year-old female twins discordant for stroke. A coincidental finding of a right-sided intracavernous cerebral anaeurysm measuring 9 mm was made in the affected twin, prior to the stroke. This has been managed conservatively ever since. The blood samples were collected and processed in parallel and a total of 59 biochemical markers were analyzed (Table 1). The data were compared with the corresponding reference intervals for the age group. These values were mostly within the normal range and similar between the sisters as expected, with the exception of marked elevation of γ-glutamyltransferase (GGT) and erythrocyte sedimentation rate (ESR) levels in the affected twin. We identified a greater than 10-fold increase in GGT (244 U/l vs. 23 U/l) and ESR (36 mm/h vs. 2 mm/h) levels in this individual. Analysis of her previous medical records indicated elevated levels of GGT (81 U/l) significantly above the normal range, 14 years prior to the onset of stroke. These values continued to increase up to when she had stroke and beyond. By contrast, GGT readings for the unaffected twin have been near constant over the same period, and always within the normal range. The medical notes also reveal significantly elevated ESR in the affected twin following the stroke. Unfortunately, no ESR readings are available prior to this period. We were able to exclude the possible effects of factors normally associated with an increase in GGT levels, including alcohol, smoking, and anticonvulsants since neither drinks appreciable and only the unaffected twin smokes; the affected twin had taken anticonvulsants during childhood but her GGT values are higher than those reported in studies showing the effect of anticonvulsants on GGT (1). GGT, a marker for oxidative stress, and an indicator of endothelial function, is known to play a role in the formation and rupture of plaques leading to atherosclerosis (2–4). Screening patients at risk of ischemic stroke for GGT and ESR should be relatively inexpensive, and GGT inhibitors are readily available (5).