Association of the G-463A myeloperoxidase polymorphism with infection in sickle cell anemia

Infections constitute a principal cause of morbidity and mortality in sickle cell anemia (SCA). Here we present evidence to suggest that a polymorphism (G-463A MPO) in the gene encoding the myeloperoxidase (MPO) enzyme, important for the host defense system, may significantly increase susceptibility to infection in SCA.     

UGT1A1 promoter polymorphisms and the development of hyperbilirubinemia and gallbladder disease in children with sickle cell anemia

Genetic modifiers contribute to phenotypic variability in patients with sickle cell anemia (SCA). The influence of the bilirubin UDP-glucuronosyltransferase (UGT) 1A1 (TA)(n)TAA promoter polymorphism on bilirubin levels and gallbladder disease in SCA was examined using prospectively collected data from the Cooperative Study of Sickle Cell Disease. A total of 324 children with HbSS (median age 6.9 years) had UGT1A1 genotyping; 243 (75%) had common (TA)(6) or (TA)(7) alleles, whereas 81 (25.0%) had variant (TA)(5) or (TA)(8) alleles. The UGT1A1 genotype significantly influenced average bilirubin levels for the common alleles: 6/6 genotype = 2.36 +/- 1.13 mg/dL, 6/7 genotype = 2.90 +/- 1.54 mg/dL, and 7/7 genotype = 4.24 +/- 2.11 mg/dL (P < 0.0001). Thirty-nine percent of children with the 7/7 genotype had documented gallbladder disease, compared with 18.2% with the 6/7 genotype and only 9.9% with the wildtype 6/6 UGT1A1 genotype (P = 0.001). To analyze the (TA)(5) and (TA)(8) variant alleles, three groups were generated, showing increasing bilirubin levels with increasing TA repeats and age. Group 3 (genotypes 6/8, 7/7, and 7/8) had a significantly greater rate of bilirubin change than Groups 1 (genotypes 5/6, 5/7, and 6/6) or 2 (genotype 6/7). These results validate previous smaller studies and confirm that the UGT1A1 promoter polymorphism exerts a powerful influence on bilirubin levels and the development of gallbladder disease in children with SCA. UGT1A1 genotyping should be considered as a screening tool for predicting children most likely to develop gallbladder disease at a young age.     

The linear effects of alpha-thalassaemia, the UGT1A1 and HMOX1 polymorphisms on cholelithiasis in sickle cell disease

Serum bilirubin levels and predisposition to gallstones in sickle cell disease (SCD) are influenced by genetic variation in the hepatic uridine diphosphate (UDP)-glucuronosyltransferase (UGT1A1) gene, but the association is not consistent. This study investigated whether variation in the gene encoding haem oxygenase (HMOX1), a rate-limiting enzyme upstream of UGT1A in the haem catabolic pathway, and alpha-thalassaemia could explain some of the inconsistent effects. The UGT1A1 [TA](n) and HMOX1 [GT](n) promoter polymorphisms and alpha globin genotypes were determined in 263 SCD patients (199 HbSS, 5 HbS/beta(0), 59 HbSC). Detection of gallstones was based on ultrasound of the liver/biliary tree. Regression analysis showed that serum bilirubin levels and the incidence of gallstones were strongly associated with the number of UGT1A1 [TA] repeats in all subjects (P < 0.0001 and P < 0.01, respectively). While HMOX1 genotype had no effect, co-inheritance of alpha-thalassaemia reduced serum bilirubin levels in all SCD patients independently of the number of UGT1A1 [TA] repeats. Each additional [TA] repeat is associated with an increase in mean serum bilirubin levels of 21% and cholelithiasis risk of 87% in SCD.     

UGT1A1 polymorphism outweighs the modest effect of deletional (-3.7 kb) alpha-thalassemia on cholelithogenesis in sickle cell anemia

Enhanced erythrocyte destruction in sickle cell anemia results in chronic hyperbilirubinemia. Only a subset of patients develop cholelithiasis. UGT1A1 promoter polymorphism is associated both with unconjugated bilirubin level and elevated risk for cholelithiasis in such subset. Here, we investigated the role of alpha-thalassemia, yet another genetic factor that modulates hemolysis, in conferring protection from cholelithiasis. We show that, although alpha-thalassemia is associated with modest reduction in hemolysis and unconjugated bilirubin level, UGT1A1 polymorphism outweighs its effect on cholethiogenesis in sickle cell anemia patients.     

UGT1A1 variation and gallstone formation in sickle cell disease

Pigment gallstones are a common clinical complication of sickle cell (SS) disease. Genetic variation in the promoter of uridine diphosphate (UDP)-glucuronosyltransferase 1A1 (UGT1A1) underlies Gilbert syndrome, a chronic form of unconjugated hyperbilirubinemia, and appears to be a risk factor for gallstone formation. We investigated the association between UGT1A1 (TA)(n) genotype, hyperbilirubinemia, and gallstones in a sample of Jamaicans with SS disease. Subjects were from the Jamaican Sickle Cell Cohort Study (cohort sample, n = 209) and the Sickle Cell Clinic at the University of the West Indies, Kingston, Jamaica (clinic sample, n = 357). The UGT1A1 (TA)(n) promoter region was sequenced in 541 SS disease subjects and 111 healthy controls (control sample). Indirect bilirubin levels for (TA)(7)/(TA)(7) and (TA)(7)/(TA)(8) genotypes were elevated compared with (TA)(6)/(TA)(6) (clinic sample, P < 10(-5); cohort sample, P < 10(-3)). The (TA)(7)/(TA)(7) genotype was also associated with symptomatic presentation and gallstones in the clinic sample (odds ratio [OR] = 11.3; P = 7.0 x 10(-4)) but not in the younger cohort sample. These unexpected findings indicate that the temporal evolution of symptomatic gallstones may involve factors other than the bilirubin level. Although further studies of the pathogenesis of gallstones in SS disease are required, the (TA)(7)/(TA)(7) genotype may be a risk factor for symptomatic gallstones in older people with SS disease.     

Association between hemolysis and albuminuria in adults with sickle cell anemia

Studies have questioned whether renal dysfunction in sickle cell disease is linked to hemolysis-associated vasculopathy. We have investigated renal function and markers of hemolysis in a cohort of 424 adult African-British patients with sickle cell disease. While significant associations were found in HbSS and HbSβ(0) (sickle cell anemia) patients with and without controlling for covariates between hemolytic markers and albuminuria, the associations were not significant in patients with HbSC. Estimated glomerular filtration rate, a marker of renal function, correlated significantly with reticulocyte count and bilirubin. Alpha thalassemia, present in 34% of the sickle cell anaemia patients, had a protective effect against albuminuria in this group. Altogether, the incidence of hyperfiltration was 71% and microalbuminuria 37%, making nephropathy a common complication of sickle cell anemia.     

Association of homocysteine and inflammatory-related molecules in sickle cell anemia

Objective: Investigate the role of homocysteine (Hcy), Th17-related cytokines, and adhesion molecules in the inflammatory state seen in the sickle cell anemia (SCA).

Methods: We studied the Hcy, interleukin (IL)-17, and transforming growth factor β (TGF-β) cytokine levels of 62 SCA patients, as well as the expression levels of inflammatory and endothelial activation markers.

Results: We found significant associations between Hcy levels and increased expression of IL-17 and TGF-β among SCA patients, and a positive significant correlation between Hcy and soluble vascular cellular adhesion molecules (sVCAM). SCA individuals had raised IL-17 levels when compared with controls.

Discussion: These results suggest a possible role of Hyc in the induction of TGF-β and IL-17. Other authors proposed that Hcy may contribute to the initiation and progression of vascular disease by monocyte activation, resulting in the secretion of cytokines that amplify the inflammatory response. The role of Hcy in cytokine production and oxidative stress in the endothelium may explain the increase of sVCAM expression and, the vascular activation currently described among the SCA individuals with the highest Hcy serum levels. The chronic inflammation was observed in hyperhomocysteinemic mice, with an increased expression of VCAM-1 and plasma levels of tumor necrosis factor-alpha, showing an association of this inflammatory molecule and vascular changes.

Conclusion: Our findings suggest that the increased levels of IL-17,Hcy and sVCAM contributes contributes to the vascular inflammation and activation presented by SCA patients, which probably have an important role in vaso-occlusion. On the basis of the presented data, IL-17 and Hcy might be considered as important components in the pathogenesis of SCA.     

The prevalence of avascular necrosis in sickle cell anemia: correlation with alpha-thalassemia

The purpose of the present study was to investigate the effect of alpha-thalassemia on the prevalence of avascular necrosis in 52 adult patients with sickle cell anemia. alpha-Globin genotypes were determined by restriction endonuclease mapping of genomic DNA extracted from peripheral blood leukocytes. Radiographs of humeral and femoral heads were interpreted by two radiologists who were not aware of the clinical picture and the genotype of the patients in the study. We present data showing that there is a significant positive correlation between alpha-gene deletion and the prevalence and extent of avascular necrosis in our patient population.     

UGT1A1*28基因多态性与小细胞肺癌

尿苷二磷酸葡糖醛酸转移酶1A1 (uridine diphosphate glucuronosyl transferase 1A1,UGT1A1)是伊立替康(Irinotecan,CPT-11)活性产物的主要代谢酶,其活性与CPT-11的疗效和不良反应均密切相关,而UGT1A1* 28基因多态性可显著降低UGT1A1酶的表达与活性.IP(伊立替康+顺铂)方案是广泛期小细胞肺癌的一线化疗方案,UGT1A1* 28基因多态性可影响IP方案的疗效及不良反应,检测UGT1A1* 28基因多态性对于指导小细胞肺癌患者的个体化治疗具有一定的临床意义.     

Priapism in sickle cell anemia in Togo: prevalence and knowledge of this complication.

Prevalence of priapism and knowledge on this disease was assessed by interviewing a group of 114 sickle cell anemia patients, 5 years and older, considered to be genotypically homogenous (Benin or #19 haplotype). Prevalence of priapism in homozygous sickle cell patients was 26.3% (30/114) and that of the control group of subjects with Hb AA was 2% (2/102) (the difference was very significant: p = 5.10-7). Actuarial probability of having priapism by 20 years of age was 69 +/- 8.5%. Few homozygous patients without a history of priapism (15.8%) have heard about priapism. This lack of knowledge, added to low accessibility of a health care system, may explain the high rate of impotence (31.6%). The results of this study led us to plan a large program of infonnation about priapism and sickle cell disease in the Togolese population.     

Stroke risk in siblings with sickle cell anemia

Cerebrovascular disease is a common cause of morbidity in sickle cell anemia (HbSS): approximately 10% of patients have a clinical stroke before 20 years of age, and another 22% have silent infarction on magnetic resonance imaging. The phenotypic variation among patients with HbSS suggests a role for modifier genes and/or environmental influences. To assess the familial component of clinical stroke in HbSS, we estimated the prevalence of clinical stroke among all patients and among HbSS sibling pairs at 9 pediatric centers. The sample included 3425 patients with sickle cell disease who were younger than 21 years, including 2353 patients with HbSS. The stroke prevalence was 4.9% for all genotypes; 7.1% for patients with HbSS; 1.1% for patients with HbSbeta(o) thalassemia; 0.6% for patients with Sbeta(+) thalassemia; and 0% for patients with HbSC. In 207 sibships, more than 1 child had HbSS. There were 42 sibships in which at least 1 sibling had a stroke, and in 10 of the 42, 2 siblings had a stroke. A permutation test indicated that the number of families in which 2 children had strokes was larger than the number expected if strokes were randomly distributed among children in sibships (P =.0012). There was no difference in stroke prevalence based on sex, nor was the mean age at stroke presentation significantly different between singletons and sibships with stroke. We conclude that there is a familial predisposition to stroke in HbSS. Attempts to identify genetic modifiers should be initiated with family-based studies.     

Serum autoantibodies in patients with sickle cell anemia

The prevalence of serum autoantibodies was determined in 50 black adult patients with sickle cell anemia, and in 33 age- and sex-matched healthy black individuals. Twenty-seven of the patients (54%) had at least one type of autoantibody, in contrast to only four (18.2%) of the control subjects (P less than .01). Antismooth muscle, antiskeletal muscle and antinuclear antibodies were the most frequently seen autoantibodies. There was no correlation between the presence of autoantibodies and history of hepatitis, number of blood transfusions or concurrent drug therapy. Sickle cell anemia is associated with the induction of autoimmune phenomena.     

Cardiac abnormalities in children with sickle cell anemia

Sickle cell anemia (SCA) results in chronic volume overload of the heart due to hemodilution. Previous echocardiographic studies of cardiac function in children with SCA have not accounted for these abnormal loading conditions. The objectives of this study were to (1) determine how the degree of anemia and transfusion status relate to cardiac findings and (2) evaluate cardiac function using load-independent parameters of function. We evaluated 77 patients with SCA, ages 2 to 22 years (mean +/- SD = 11.7 +/- 4.7), using physical examination, electrocardiography, and echocardiography. We compared two groups of patients. Group 1 consisted of 57 non-transfused patients, and Group 2 consisted of 20 patients on a chronic transfusion protocol. Group 1 patients exhibited a significantly lower hemoglobin, higher cardiac output, and larger left ventricular (LV) end-diastolic dimension and LV mass than groups 2 (P < 0.05). However, the velocity of circumferential fiber shortening-wall stress index (a load-independent measure of systolic function) was normal and not statistically different between the two groups. Conversely, the LV myocardial performance index (a measure of combined systolic and diastolic function) was significantly higher in Group 2 (P < 0.001), possibly indicating impaired myocardial diastolic function. SCA in children results in a volume-overloaded heart with a significant increase in LV dimensions and mass, both proportional to the degree of anemia. Despite these abnormal loading conditions, systolic function is preserved. Patients on a chronic transfusion protocol may develop diastolic dysfunction despite iron chelation therapy.     

Isobutyramide therapy in patients with sickle cell anemia

We have administered Isobutyramide as a suspension over a period of 3 months, from a starting dose of 50 mg/kg/day up to 150 mg/kg/day, to four adult sickle cell (SS) anemia patients. The maximum dose was maintained for 3 weeks. The blood counts remained stable and the Hb F levels decreased slightly. The ^Gγ levels increased at the end of the trial, suggesting activation of the ^Gγ gene at the highest dose of Isobutyramide. Three patients showed a stable rate of hemolysis, while in one patient, an increase of lactate dehydrogenase occurred. None of the patients experienced pain crisis or organ-specific crisis, but all four complained about mild epigastric burning and a bitter taste. After the first month of treatment one patient complained about intolerable epigastric discomfort which was relieved by Omeprazole. Another patient complained about increasing dyspepsia in the 12th week leading to the termination of the trial. Oral Isobutyramide administration does not qualify as an effective treatment of SS patients. © 1995 Wiley-Liss, Inc.     

Hypothyroidism in adults with sickle cell anemia.

Persons with sickle cell anemia have several indications for transfusion of red blood cells. One of the complications of transfusion of red blood cells is iron overload. Iron overload has been associated with multiple endocrine abnormalities. We report herein three cases of hypothyroidism in adult individuals with sickle cell disease. All three patients were over the age of 45 years at the time of the diagnosis and had received multiple units of transfused red blood cells and had serum ferritin levels of greater than 6,000 ng/mL. All patients were diagnosed during times when they were critically ill. Replacement therapy was instituted in all cases; however, all three patients died shortly after the diagnosis of hypothyroidism was made. Congestive heart failure appeared to be a primary cause of death in all three patients. In the one patient in whom a postmortem examination was done, there was evident extensive fibrosis of the thyroid gland as well as extensive deposition of iron in the cells lining the thyroid follicles. We believe that this represents the first report of clinical hypothyroidism in patients with sickle cell anemia who have received multiple transfusions. Awareness of this condition is especially important given that congestive heart failure is common in sickle cell disease.