Transcranial color Doppler in stroke-free adult patients with sickle cell disease

A-296G variant of THBS1 gene (rs1478605) is associated with a lower frequency of stroke in a Brazilian population with sickle cell anemia

OBJECTIVES

Stroke is a devastating clinical outcome that significantly contributes to the morbidity and mortality of sickle cell anemia (SCA) patients. Despite its advantages in predicting stroke risk, transcranial Doppler screening has limitations that restrict its applicability, highlighting the need for emerging prognostic tools. Thrombospondin-1 plays a crucial role in endothelial injury, platelet adhesion, and nitric oxide metabolism and may be implicated in stroke pathophysiology. Here, we aimed to evaluate the association of THBS1 genetic variations with the occurrence of stroke in SCA patients MATERIALS AND METHODS: By real-time PCR, 512 SCA patients were fully genotyped for THBS1 A-296G (rs1478605) polymorphism RESULTS: THBS1 GG genotype was associated with a lower risk for stroke occurrence [odds ratio (OR): 0.30; 95% confidence interval (CI): 0.11-0.78; P = 0.011], although these findings were not consistent with multivariate logistic regression analysis (OR: 0.73, 95% CI: 0.12 - 4.37; P = 0.736). In agreement, the cumulative incidence of stroke for patients with AG/AA genotypes was higher when compared to the GG genotype (P = 0.018). However, the association was not maintained in the multivariate proportional hazards model (hazard ratio: 0.67, 95% CI: 0.12-3.61; P = 0.643) CONCLUSIONS: In summary, the present study shows that the THBS1 A-296G (rs1478605) polymorphism may be a potential modifier for stroke in SCA.

Transcranial color-coded duplex sonography reliably identifies intracranial vasculopathy in adult patients with sickle cell disease

In order to prevent stroke, screening for disease-related intracranial vasculopathy using Doppler ultrasound is recommended in sickle-cell disease (SCD) children. How to screen such vasculopathy in adults remains largely unknown. The objective of this study was to assess whether transcranial color-coded duplex sonography (TCCD) is sensitive and specific enough to identify SCD adult patients with vasculopathy, compared with magnetic resonance angiography (MRA). Sickle cell disease adults followed in referral centers at high risk of vasculopathy were included in this study. Transcranial color-coded duplex sonography examination and 3-D time-of-flight MRA were performed on the same day. On MRA, vasculopathy was defined by the presence of at least one ≥50% arterial stenosis. On TCCD, vasculopathy was defined by a time-averaged mean of the maximum velocity (TAMx) stenotic/prestenotic ratio ≥ 3, an occlusion, or a Moyamoya pattern. Vasculopathy was also considered as present when TAMx ratio could not be calculated because of the presence of severe cervical lesions. Among 80 included patients, quality of MRA was insufficient in three patients. Among the 38 patients with vasculopathy on MRA, 37 had a vasculopathy according to TCCD criteria: TAMx ratio ≥ 3 or intracranial occlusion in 33 patients and cervical lesion in four patients. A Moyamoya pattern was identified with TCCD in all 17 patients with Moyamoya on MRA. Sensitivity and specificity of TCCD to identify patients with ≥50% vasculopathy on MRA were (n = 37/38) 97% and (n = 28/34) 82%, respectively. Positive and negative predictive values were (n = 37/43) 86% and (n = 28/29) 97%, respectively. Note, TCCD may be used to identify SCD adult patients with vasculopathy.

Evaluation of oxidative stress-related genetic variants for predicting stroke in patients with sickle cell anemia

Overt stroke in adults with sickle cell anemia (SCA) continues to be a major cause of morbidity and mortality, while no evidence-based strategy for prevention has been reached so far. Although transcranial Doppler ultrasonography represents the most important tool for identifying young patients with SCA at risk of primary stroke, strategies for stroke prediction in adulthood remain challenging. Emerging data suggest that oxidative stress may exert a pivotal role in the pathogenesis of ischemic brain injury. Combining these pieces of evidences with the well-known genetic contribution to the development of stroke in SCA, we hypothesized that genetic variants related to the biology of oxidative stress could be used to identify adult patients at higher risk of stroke. Overall, 499 unrelated patients with SCA aged >18 years were genotyped for SOD2 Val16Ala (rs4880), GPX3 T-568C (rs8177404), GPX3 T-518C (rs8177406), GPX3 T-65C (rs8177412), and CAT01 C-262 T (rs1001179) polymorphisms, along with α-thalassemia status and β-globin gene haplotypes. Of these, only the SOD2 Val16Ala polymorphism was associated with stroke. SOD2 Val16Ala polymorphism was independently associated with risk of stroke (odds ratio: 1.98; 95% confidence interval [CI]: 1.18-3.32; P = .009) and with the long-term cumulative incidence of stroke (hazard ratio: 2.24, 95% CI: 1.3-3.9; P = .004). In summary, we provide evidence that oxidative stress-related genetic variants, in particular, the SOD2 Val16Ala polymorphism, may represent a simple and inexpensive alternative for identifying patients at risk of stroke.

Assessment of Atherosclerosis in Peripheral and Central Circulation in Adult β Thalassemia Intermedia Patients by Color Doppler Ultrasound: Egyptian Experience

BACKGROUND

Atherosclerosis has been extensively studied in thalassemia major (TM) and sickle cell disease but not yet in β thalassemia intermedia (TI). Previous studies concerned with TM were performed in children. TI patients usually live longer and, thus, are more prone to complications of atherosclerosis.

AIM

In our study, we applied color Doppler for the determination of arterial conduit and flow velocities in β TI patients.

METHODS

For central circulation, we measured right and left middle cerebral arteries (MCAs) and basilar artery (BA) mean flow velocity (MFV), pulsatility index (PI), and peak systolic velocity (PSV) as well as carotid intimal media thickness, and to assess peripheral circulation, we studied ankle/brachial index and posterior and anterior tibial arteries' (ATA, PTA) pressure and PSV. This was applied for 30 adult TI patients and 20 age-, sex-, and ethnic group-matched controls.

RESULTS

Transcranial Doppler findings among cases and controls showed that the MFV, PSV of MCAs, and PSV, PI, and MFV of the BA were statistically higher in cases than controls. A comparison between splenectomized and nonsplenectomized patients showed that total leukocyte count, platelet count, lactate dehydrogenase, ferritin, PSV and MFV of the left MCA were all statistically higher in splenectomized cases. Differences between males and females with TI with respect to laboratory and Doppler findings were all statistically insignificant except for intima media thickness, PTA pressure, ATA pressure, and PSV.

CONCLUSION

More than one parameter should be applied to assess atherosclerosis in TI. There is evidence of an increased risk of central ischemia rather than peripheral ischemia in these patients.

Cardiovascular complications of sickle cell disease

Sickle cell disease (SCD) is the most common inherited blood disorder in the United States, and a global health problem. Pathological features of the abnormal hemoglobin (HbS) result in 2 hallmarks of the disease - recurrent episodes of acute microvascular occlusion and chronic hemolytic anemia - that inflict continuous and insidious damage to multiple organs. With improved childhood survival, SCD in adults has evolved into a chronic degenerative disease with underlying damage to multiple organs including the heart and lungs. Cardiopulmonary complications, including cardiomyopathy, diastolic dysfunction, pulmonary hypertension (PH), and sudden cardiac death are the most common causes of morbidity and mortality. Awareness of the sickle-related cardiovascular phenotypes is important for screening, early diagnosis, and intervention of cardiac complications in this disorder.

Current challenges in the management of patients with sickle cell disease - A report of the Italian experience

Sickle cell disease (SCD) is an inherited red blood cell disorder caused by a structural abnormality of hemoglobin called sickle hemoglobin (HbS). Clinical manifestations of SCD are mainly characterized by chronic hemolysis and acute vaso-occlusive crisis, which are responsible for severe acute and chronic organ damage. SCD is widespread in sub-Saharan Africa, in the Middle East, Indian subcontinent, and some Mediterranean regions. With voluntary population migrations, people harboring the HbS gene have spread globally. In 2006, the World Health Organization recognized hemoglobinopathies, including SCD, as a global public health problem and urged national health systems worldwide to design and establish programs for the prevention and management of SCD. Herein we describe the historical experience of the network of hemoglobinopathy centers and their approach to SCD in Italy, a country where hemoglobinopathies have a high prevalence and where SCD, associated with different genotypes including ß-thalassemia, is present in the native population.