The influence of uridine diphosphate glucuronosyl transferase 1A promoter polymorphisms, beta-globin gene haplotype, co-inherited alpha-thalassemia trait and Hb F on steady-state serum bilirubin levels in sickle cell anemia

Influence of UGT1A1 promoter polymorphism, α-thalassemia and βs haplotype in bilirubin levels and cholelithiasis in a large sickle cell anemia cohort

Hyperbilirubinemia in patients with sickle cell anemia (SCA) as a result of enhanced erythrocyte destruction, lead to cholelithiasis development in a subset of patients. Evidence suggests that hyperbilirubinemia may be related to genetic variations, such as the UGT1A1 gene promoter polymorphism, which causes Gilbert syndrome (GS). Here, we aimed to determine the frequencies of UGT1A1 promoter alleles, alpha thalassemia, and β^S haplotypes and analyze their association with cholelithiasis and bilirubin levels. The UGT1A1 alleles, -3.7 kb alpha thalassemia deletion and β^S haplotypes were determined using DNA sequencing and PCR-based assays in 913 patients with SCA. The mean of total and unconjugated bilirubin and the frequency of cholelithiasis in GS patients were higher when compared to those without this condition, regardless of age (P < 0.05). Cumulative analysis demonstrated an early age-at-onset for cholelithiasis in GS genotypes (P < 0.05). Low fetal hemoglobin (HbF) levels and normal alpha thalassemia genotype were related to cholelithiasis development (P > 0.05). However, not cholelithiasis but total and unconjugated bilirubin levels were associated with β^S haplotype. These findings confirm in a large cohort that the UGT1A1 polymorphism influences cholelithiasis and hyperbilirubinemia in SCA. HbF and alpha thalassemia also appear as modulators for cholelithiasis risk.

Influence of Nutrition on Disease Severity and Health-related Quality of Life in Adults with Sickle Cell Disease: A Prospective Study

Background & Aims

Sickle cell disease (SCD), a genetic disorder resulting from the presence of a mutated hemoglobin S (HbS), has a worldwide distribution and causes significant morbidity and mortality in children and adults. Few studies addressed the determinants of SCD severity in adults; therefore, we investigated the impact of nutrition on the outcome of SCD and health-related quality of life (HRQoL) in adult patients.

Methods

In this longitudinal study, we recruited and prospectively followed 62 adults with SCD (aged ≥18 years) for a median of 93 months. At entry and follow-up, patients provided medical and dietary history, had a physical examination and anthropometric measurements, assessed protein-energy intake, measurement of micronutrient levels, estimation of SCD severity score, and determination of the HRQoL (SF-26v2). The study outcome was a composite of hospitalization due to SCD crises or death.

Results

At baseline, 42 (67.74%) patients had macro and, or micro-undernutrition (Group A), and 20 (32.26%) were well nourished. (Group B). The BMI and most anthropometric measurements were significantly lower in SCD patients compared to control subjects. Seventy percent of SCD patients had vitamin D, vitamin B12, and zinc deficiencies. Thirty-six under-nourished patients (86%) had gastrointestinal disorders. During follow-up, 46 patients (74.19%) developed one or more vaso-occlusive pain crises or other SCD related complications that required hospitalization. Significant differences in most SF-36v2 domains existed between well-nourished and undernourished SCD patients. Protein-energy and micronutrient deficiencies were independent predictors of severe SCD and mortality. Correction of undernutrition and hydroxyurea therapy improved SCD severity scores and HRQoL.

Conclusions

Patients with sickle cell disease have various degrees of macro and micro deficiencies, which increase SCD severity and hospitalizations and reduce the health-related quality of life. Early diagnosis and prompt correction of macro and micronutrient deficiencies need to be incorporated in the standard of care of SCD patients to improve the disease outcomes.

Influence of beta-cluster haplotypes, alpha-gene status and UGTA1 polymorphism on clinical and hematological data in sickle-cell disease children from French Guiana

OBJECTIVES

This cross-sectional study aimed to investigate the influence of haplotypes, alpha-gene status and UGTA1 polymorphism on the severity of sickle cell disease in children.

METHODS

This cross-sectional study was conducted between 2012 and 2014 at the Cayenne Hospital, in French Guiana. Acute clinical complications were grouped into (i) severe SCD defined by the presence of stroke and/or abnormal-transcranial Doppler (TCD), (ii) moderate SCD defined by the presence of at least three annual events requiring hospitalization and/or at least one acute chest syndrome, (iii) no severe SCD (in the absence of the precited events).

RESULTS

Among the 86 patients, 33.7% were female with a median age of 10 years (range: 6-12 years). The vast majority of patients had SCA (HbSS) phenotype (74.4%; n = 64). The severe haplotype was found in 40% of patients. 30% were BEN/BEN. Analysis of α-globin gene deletions revealed that 32 patients (37.2%) were heterozygous (loss of 2 genes in 2 cases and loss of 1 gene in 30 cases) for α-thalassemia (3.7 kb deletion). Homozygous (TA) n TA7/7 was found in 24 (28%). In the multivariate analysis, the factors associated with the severity of sickle cell disease were the first vaso-occlusive crisis before one year of age (OR 25, [95% CI = 6.0-107.0], p<0.001) and a baseline MCV >80 fL (OR 0.20 [95% CI = 0.04-0.96], p = 0.04). The area of the ROC curve was 0.90.

CONCLUSION

Prospective studies with greater statistical power would provide more knowledge on the relationship between UGT1A1 mutations and the clinical and hematological manifestations of SCA.

Uridine diphosphate glucuronosyl transferase 1A (UGT1A1) promoter polymorphism in young patients with sickle cell anaemia: report of the first cohort study from Nigeria

Background

(TA) n repeat sequence (rs8175347) of UGT1A1 gene promoter polymorphism is associated with serum bilirubin levels and gallstones among different sickle cell anaemia (SCA) populations. There are no data on UGT1A1 polymorphisms and their impact on Nigerian SCA patients. In this study, we determined the distribution of the UGT1A1 (TA) n genotypes among a group of young Nigerian SCA patients and healthy controls. In addition, the influence of UGT1A1 (TA) n genotypes on the laboratory and clinical events among the patients was determined.

Methods

The distribution of the UGT1A1 (TA) n genotypes among 101 young Nigerian SCA patients and 64 normal appropriate controls were determined and studied. The UGT1A1 (TA) n genotypes were further classified into subgroups and used to differentiate the clinical events and laboratory parameters of the patients.

Results

Four (TA) n alleles:(TA)5, 6, 7, and 8 were found. These were associated with 10 genotypes: TA5/5, 5/6, 5/7, 5/8, 6/6, 6/7, 6/8, 7/7, 7/8, 8/8. The normal (wild-type)-(TA) 6/6), low- (TA) 7/7, 7/8, 8/8), intermediate- (TA) 5/7, 5/8, 6/7, 6/8), and high-activity (TA) 5/5, 5/6,) genotypes were found in 24.8, 24.8, 41.5, and 8.9% patients and 20.3, 15.6, 61, and 3.1% controls respectively. The general genotype distribution of the patients and control group were not significantly different. There were significant differences in serum bilirubin and lactate dehydrogenase (LDH) of the patients when differentiated by the UGT1A1 (TA) n genotypes (p<0.05). Asymptomatic gallstones were found in 5.9% of patients and were significantly of the low-activity genotypes sub-group 5 (20%) vs 1(1.3%) p = 0.0033. Although, bilirubin and fetal hemoglobin (HbF) of patients with gallstones were significantly different from those without gallstone, only the serum bilirubin was associated with UGT1A1 (TA) n genotypes on multivariate analysis (p < 0.0001).

Conclusion

This study highlights the contribution of UGT1A1 polymorphisms, a non-globin genetic factor, to the laboratory and clinical manifestations of young Nigerian SCA patients for the first time. It also shows that children with co-inheritance of low UGT1A1 (TA) n affinity genotypes may be at risk of gallstone, hence the need to follow them up.

Thalassemia in the laboratory: pearls, pitfalls, and promises

Thalassemia is one of the most common hereditary disorders of the developing world, and it is associated with severe anemia and transfusion dependence. The global health burden of thalassemia has increased as a result of human mobility and migration in recent years. Depending on inherited mutations, thalassemia patients exhibit distorted hemoglobin (Hb) patterns and deviated red cell indices, both of which can be used to support identification by diagnostic tools. Diagnostic approaches vary depending on the target population and the aim of the testing. Current methods, which are based on Hb patterns, are used for first-line screening, whereas molecular testing is needed for conformation of the results and for prenatal and preimplantation genetic diagnosis. In the present paper, we review the diagnostic parameters, pitfalls, interfering factors, and methods; currently available best-practice guidelines; quality assurance and standardization of the procedures; and promising laboratory technologies for the future of thalassemia diagnosis.

Minireview: Clinical severity in sickle cell disease: the challenges of definition and prognostication

Sickle cell disease (SCD) is a monogenic, yet highly phenotypically variable disease with multisystem pathology. This manuscript provides an overview of many of the known determinants, modifiers, and correlates of disease severity in SCD. Despite this wealth of data, modeling the variable and multisystem pathology of SCD continues to be difficult. The current status of prediction of specific adverse outcomes and global disease severity in SCD is also reviewed, highlighting recent successes and ongoing challenges.

Serum Total Bilirubin, not Cholelithiasis, is Influenced by UGT1A1 Polymorphism, Alpha Thalassemia and β(s) Haplotype: First Report on Comparison between Arab-Indian and African β(s) Genes

Background

We explored the potential relationship between steady state serum bilirubin levels and the incidence of cholelithiasis in the context of UGT1A1 gene A(TA)nTAA promoter polymorphism in Omani sickle cell anemia (SCA) patients, homozygotes for African (Benin and Bantu) and Arab-Indian β^S haplotypes, but sharing the same microgeographical environment and comparable life style factors.

Methods

136 SCA patients were retrospectively studied in whom imaging data including abdominal CT scan, MRI or Ultrasonography were routinely available. Available data on the mean steady state hematological/biochemical parameters (n=136), β^s haplotypes(n=136), α globin gene status (n=105) and UGT1A1 genotypes (n=133) were reviewed from the respective medical records.

Results

The mean serum total bilirubin level was significantly higher in the homozygous UGT1A1(AT)₇ group as compared to UGT1A1(AT)₆ group. Thus, not cholelithiasis but total serum bilirubin was influenced by UGT1A1 polymorphism in this SCA cohort.

Conclusion

As observed in other population groups, the UGT1A1 (AT)₇ homozygosity was significantly associated with raised serum total bilirubin level, but the prevalence of gallstones in the Omani SCA patients was not associated with α thalassaemia, UGT1A1 polymorphism, or β^s haplotypes.

UGT1A1 promoter polymorphism associated with serum bilirubin level in Saudi patients with sickle cell disease

BACKGROUND AND OBJECTIVES

Polymorphism in (TA)n of the UGT1A1 promoter influences bilirubin level and risk of gallstones in patients with sickle cell disease (SCD) of African descent. Modifiers of bilirubin level and gallstones in Saudi patients with SCD are not known.

DESIGN AND SETTINGS

Patients with SCD presenting to participating institutions between July 2009 and July 2012 were enrolled in our study.

METHODS

A total of 223 SCD patients were enrolled. Laboratory workup at steady state included complete blood count, reticulocytes, serum bilirubin, lactate dehydrogenase (LDH), G6PD level, and hemoglobin (Hb) electrophoresis. The (TA)n UGT1A1 promoter polymorphism and presence of a-thalassemia were also deter.mined.

RESULTS

TA6/6 in the UGT1A1 promoter was identified in 189 patients (84.7%), TA7/7 in 26 (11.7%), TA5/5 in 6 (2.7%), and TA5/6 in 2 (0.9%). Increased (TA)n of the UGT1A1 promoter (P < .0001), male gender (P=.02), higher LDH (P=.001), and lower Hb level (P=.009) were associated with higher bilirubin level, while the co-inheritance of a-thalassemia (P=.003) was linked with lower bilirubin level. UGT1A1 (TA)n (P < .0001) and Hb level (P=.005) remained significant on multivariate analysis. Gallstones were more frequent in patients with TA7/7 (72%) compared to patients with TA6/6 (57%) and TA5/5 or 5/6 (37%); however, this difference was not statistically significance (P=.18). Older age (P=.0001) and absence of a-thalassemia (P=.03) were associated with higher risk of gallstones.

CONCLUSION

(TA)n in the UGT1A1 promoter and intensity of hemolysis modify steady-state serum bilirubin level in SCD. Co-inheritance of a-thalassemia reduces the risk of gallstones in Saudi patients with SCD.

Association of variant alleles of MBL2 gene with vasoocclusive crisis in children with sickle cell anemia

Vasoocclusive crisis (VOC) is the major cause of morbidity and mortality in sickle cell anemia (SCA), which is caused by the occlusion of blood vessels, followed by ischemia or infarct, resulting in progressive damage to organs. However, this clinical manifestation is variable, indicating that this process could be influenced by modifier genes. The gene MBL2 which codes for mannose-binding lectin (MBL) has been associated with modifications in the progression of infectious and inflammatory vascular diseases. The aim of this study was to determine the frequency of the polymorphisms of exon 1 (alleles A/O) and promoter region -221 (alleles Y/X) of MBL2 in children with SCA and to verify their association with VOC. The determination of the polymorphism of exon 1 and the promoter region of MBL2 was performed by SYBR GREEN((R)) and Taqman((R)) system, respectively. In the patients with SCA, the frequency of the genotype related to high production of MBL was 0.46 (YA/YA) and for intermediate/low production was 0.54 (YA/XA, XA/XA, YA/YO, XA/YO, YO/YO). The frequency of the genotypes and haplotypes of MBL2 in patients with SCA did not differ from control individuals. The populations were in Hardy-Weinberg equilibrium. The patients were divided into two groups. The groups were separated by the frequency of VOC, which was defined by the total of VOC episodes divided by the age of the children at the end of this study. Since, we choose a cut point in FVOC <1 (n=48) (which we considered of mild presentation of disease) and FVOC >or=1 (n=39) (higher severity). In children with SCA, the frequency of the genotypes of MBL2 of intermediate/low expression for MBL was associated with FVOC >or=1 (p=0.0188 OR=3.15 CI=1.19-8.50). The results suggest that MBL2 polymorphism at promoter and first exon of MBL2 associated with low serum levels and structural alterations of MBL could modify the phenotype of the child with SCA related to VOC.

Sickle Cell Disease: A Multigenic Perspective of a Single Gene Disorder

The phenotypic heterogeneity of sickle cell disease continues to puzzle clinicians and investigators more than half a century after the elucidation of its molecular basis. Although advances have been made in understanding the influences of globin gene-related factors such as alpha-thalassemia (thal) and high Hb F determinants, these are far from providing a satisfactory explanation to the variation and clinical diversity of sickle cell disease in many cases. The sequencing of the human genome and the development of novel technologies such as high throughput genotyping and analysis of gene expression through cDNA microarrays has made it possible to investigate this diversity with these approaches and identify novel genetic modifiers of sickle cell disease. This brief review focuses on the recent advances in our understanding of the impact of non globin genetic modifiers on the phenotypic diversity of the disease.

Surgical and obstetric outcomes in adults with sickle cell disease

BACKGROUND

Sickle cell disease patients are more likely than the general population to undergo surgery and usually do so at a younger age. Female sickle cell disease patients also have special gynecological and obstetric issues related to their disease.

METHODS

We collected data through standardized clinical report forms, patient interviews, and medical records from 509 adult sickle cell disease patients. Logistic regression was used to estimate the association between multiple variables and each of the surgery types. We also determined the prevalence and outcomes of pregnancy in 284 women with sickle cell disease in this population.

RESULTS

Almost 50% of patients aged 18-27 years had had a cholecystectomy. Mean corpuscular hemoglobin, total bilirubin, and lactate dehydrogenase were significantly higher in the postcholecystectomy group; 9.5% of 504 individuals had undergone splenectomy. Hematocrit, body mass index, and red blood cell count were significantly higher in the postsplenectomy group. Hip replacement had been performed in 9.2% of individuals, with the prevalence increasing as early as the fourth decade and continuing to increase through the sixth decade of life. A history of pregnancy was present in 190 women (67%). Of 410 pregnancies, only 53.9% resulted in live births, 16.6% were voluntarily terminated, and 29.5% were complicated by miscarriage, still birth, or ectopic implantation.

CONCLUSIONS

Sickle cell disease continues to have a strong effect on the mean age for common surgeries and impacts pregnancy outcomes. We conclude that this population has a unique surgical and obstetric history that should be further studied to provide insight into potentially more effective preventive approaches to end-organ damage.