G6PD deficiency, absence of α-thalassemia, and hemolytic rate at baseline are significant independent risk factors for abnormally high cerebral velocities in patients with sickle cell anemia

Abstract

Stroke is predicted by abnormally high cerebral velocities by transcranial doppler (TCD).

Prevalence of transcranial Doppler abnormalities in Nigerian children with sickle cell disease

“…The median number of liver laboratory evaluations (LLEs) per patient during follow-up was 3 (range: [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], with a median time between the first and last LLE of 3.6 years (range: 1 month to 30 years).…”

“…This is consistent with the findings on the Creteil cohort [17] which showed a progressive decline in flow velocities with increasing age after the age of 4-5 years and the majority of the children in our study were older than age 5years. Glucose 6 phosphate deficiency, anemia, and hemolysis have been reported as significant and independent risk factors for abnormally high velocities [18,30]. CR velocities occur more frequently in Nigerian children with HbSS disease than their African-American counterparts.…”

Intravascular hemolysis and the pathophysiology of sickle cell disease

“…Compounding the effects of these NO-and arginine-scavenging pathways, lysed red cells release asymmetric dimethylarginine, an endogenous inhibitor of NOS (18). A role for intravascular hemolysis in promoting endothelial dysfunction was bolstered by epidemiological cohort studies linking laboratory biomarkers of the intensity of hemolytic anemia and risk of developing specific complications of SCD, including PH (19), cutaneous leg ulceration (20,21), priapism (22), stroke (23), and, recently, pro- hyperhemolysis (19,39,44,(48)(49)(50)(51)(52)(53)(54)(55)(56). PH, either screened for with TRV or definitively ascertained by right heart catheterization, is closely associated with the intensity of hemolysis and mortality (discussed below).…”

Reply: Genetic polymorphisms and cerebrovascular disease in children with sickle cell anemia from Rio de Janeiro, Brazil

“…The majority of reports have stated that co-inheritance with SCA confers a protective effect against cerebrovascular disease (CVD) [2][3][4][5][6][7] . Furthermore, a decrease in the frequency of abnormalities in transcranial Doppler has been observed in patients with alpha thalassemia 8,9 . Although our results did not show statistical significance, children with alpha thalassemia have had fewer CVD events 15.8% (3/19) than those without alpha thalassemia 84.2% (16/19).…”

“…However, it is clear that different populations present peculiarities that characterize and differentiate them from each other. Bernaudin et al report that in France, β S haplotypes were not related to CVD 9 . In Brazil (Salvador), at least one chromosome Bantu was observed in patients with a history of CVD 11 .…”