Sickle cell disease in Saudi Arabs in early childhood

Sickle cell disease in Gulf Cooperation Council countries: a systematic review

INTRODUCTION

Evidence related to the national burden of Sickle Cell Disease (SCD) in Gulf Cooperation Council (GCC) largely fragmented. Thus, the aim of this study is to systemically review studies from GCC countries to assess the epidemiological profile of SCD.

AREAS COVERED

We searched combinations of key terms in MEDLINE/PubMed, CINAHL, and EMBASE. We selected relevant observational studies reporting the frequency, incidence, prevalence, risk factors, mortality rate, and complications of SCD among the GCC population. Studies restricted to laboratory diagnostic tests, experimental and animal studies, review articles, case reports and series, and conference proceedings and editorials were excluded. A total of 1,347 articles were retrieved, out of which 98 articles were found to be eligible and included in the study. The total number of participants from all the included studies was 3496447. The prevalence of SCD ranged from 0.24%-5.8% across the GCC and from 1.02%-45.8% for the sickle cell trait. Consanguineous marriage was a risk factor for likely giving children affected with hemoglobinopathies.

EXPERT OPINION

The prevalence of SCD and its complications vary among GCC. Because of the high prevalence of SCD and its complications, health authorities should focus on more rigorous prevention and treatment strategies.

Targeting fetal hemoglobin expression to treat β hemoglobinopathies

INTRODUCTION

Sickle cell disease and β thalassemia are the principal β hemoglobinopathies. The complex pathophysiology of sickle cell disease is initiated by sickle hemoglobin polymerization. In β thalassemia, insufficient β-globin synthesis results in excessive free α globin, ineffective erythropoiesis and severe anemia. Fetal hemoglobin (HbF) prevents sickle hemoglobin polymerization; in β thalassemia HbF compensates for the deficit of normal hemoglobin. When HbF constitutes about a third of total cell hemoglobin, the complications of sickle cell disease are nearly totally prevented. Similarly, sufficient HbF in β thalassemia diminishes or prevents ineffective erythropoiesis and hemolysis.

AREAS COVERED

This article examines the pathophysiology of β hemoglobinopathies, the physiology of HbF, intracellular distribution and the regulation of HbF expression. Inducing high levels of HbF by targeting its regulatory pathways pharmacologically or with cell-based therapeutics provides major clinical benefit and perhaps a "cure."

EXPERT OPINION

Erythrocytes must contain about 10 pg of HbF to "cure" sickle cell disease. If HbF is the only hemoglobin present, much higher levels are needed to "cure" β thalassemia. These levels of HbF can be obtained by different iterations of gene therapy. Small molecule drugs that can achieve even modest pancellular HbF concentrations are a major unmet need.

The effect of sickle cell anemia on the linear growth of Nigerian children

OBJECTIVES

Despite the high prevalence of children with sickle cell anaemia (SCA) in West Africa, there is paucity of data on the height velocity and prevalence of growth failure in SCA patients. With advances in clinical care of SCA patients, could there be a spatial and secular trend in the growth pattern of these children? Hence, the compelling needs to embark on this study. The objectives of the study were to determine the prevalence of growth failure among patients with SCA and its correlation with age, gender and age at diagnosis.

METHODS

A Prospective longitudinal study of a cohort of sickle cell anaemic paediatric patients from Pediatrics SCA Clinic, University of Nigeria Teaching Hospital, Ituku Ozalla. Patients were enrolled over a period of two years using a non-parametric convenient sampling method. Their heights were measured at baseline, three months, six months and at 12 months intervals and subsequently plotted on a standard WHO growth chart. The height velocities at different monthly intervals were calculated and compared with the WHO standard normal linear growth rates) for children (used as control) to identify those with GF. (i.e. <10th percentile). The main outcome measures were the mean height velocities at different months' intervals calculated and compared using the repeated measurement analysis of variance (ANOVA) and the Wilcoxon signed test.

RESULTS

A cohort of 316 children aged 1-18 years with SCA was evaluated with a male preponderance of 161 (57.4%). The mean age and age at diagnosis were 11.04 ± 5.56 and 4.2 ± 1.7 years, respectively. The prevalence of growth failure and short stature was 84.7%. The burden of GF was highest among post-pubertal participants (94.1%). The most important predictor of growth velocity deficit was age (R²=0.045, standard β coefficient = -0.22, t=-03.51, p=0.001).

CONCLUSIONS

The study demonstrated high prevalence of growth failure in children and adolescents with SCA which intensified with advancement in age and older age at diagnosis.

Fetal hemoglobin in sickle cell anemia

Fetal hemoglobin (HbF) can blunt the pathophysiology, temper the clinical course, and offer prospects for curative therapy of sickle cell disease. This review focuses on (1) HbF quantitative trait loci and the geography of β-globin gene haplotypes, especially those found in the Middle East; (2) how HbF might differentially impact the pathophysiology and many subphenotypes of sickle cell disease; (3) clinical implications of person-to-person variation in the distribution of HbF among HbF-containing erythrocytes; and (4) reactivation of HbF gene expression using both pharmacologic and cell-based therapeutic approaches. A confluence of detailed understanding of the molecular basis of HbF gene expression, coupled with the ability to precisely target by genomic editing most areas of the genome, is producing important preliminary therapeutic results that could provide new options for cell-based therapeutics with curative intent.

Epidemiology of Thalassemia in Gulf Cooperation Council Countries: A Systematic Review

Background

Thalassemia has a burden on the healthcare systems of many countries. About 56000 conceptions result in thalassemia, globally.

Objective

To assess the epidemiological profile of thalassemia in the Gulf Cooperation Council (GCC) countries.

Methods

A systematic search was conducted in MEDLINE/PubMed (National Library of Medicine), CINAHL, and Embase. Relevant observational studies reporting the epidemiology of thalassemia among the GCC population were selected. Data on the prevalence, frequency, and complications of thalassemia were extracted. The quality of the retrieved studies was assessed according to the Newcastle-Ottawa Quality Assessment Scale.

Results

Eighteen studies (14 cross-sectional studies, two retrospective observational studies, and two retrospective analysis) with a total of 3343042 participants were included in this systematic review. Of the 18 studies, 11 studies were conducted in Saudi Arabia, two in the Kingdom of Bahrain, one in Kuwait, three in the United Arab Emirates (UAE), and one in Qatar. The prevalence of thalassemia among children below five years of age ranged from 0.25% to 33%, while it was 0.9% in children above five years and from 0.035% to 43.3% among adult thalassemia patients. The most-reported risk factors were consanguineous marriage and high-risk marriage. There was a lack of data regarding mortality rates in thalassemia.

Conclusions

Despite the premarital screening and genetic counseling (PMSGC) program for thalassemia, the incidence of high-risk couple marriages in GCC countries cannot be effectively diminished. This study suggested that the PMSGC program should adopt more attention for the high-risk areas, to enhance the level of consciousness about the hemoglobinopathy diseases and the consequences of consanguinity among the at-risk couple.

Marked regional variations in the prevalence of sickle cell disease and β-thalassemia in Saudi Arabia: findings from the premarital screening and genetic counseling program

BACKGROUND

Hemoglobinopathies represent a major public health problem in Saudi Arabia (SA). Reports suggest that their higher prevalence is not evenly distributed in SA. Regional differences were studied in sickle cell disease and β-thalassemia and their at-risk marriages using national data.

METHODS

The carrier and case status of sickle cell disease and β-thalassemia were determined in couples approaching marriage between 2004 and 2009 using standard blood tests. Prevalence of both diseases and at-risk marriages in different SA administrative and geographical regions were calculated and compared.

RESULTS

A total of 15,72,140 men and women were examined over 6 years. This represented 0.06% of the entire population of Saudi Arabia. The prevalence of couples who tested positive for sickle cell was 45.1 (42.4 for carriers and 2.7 for cases) per 1000 persons examined. The prevalence was highest in the Eastern region (134.1 per 1000), followed by Southern and Western regions (55.6 and 28.5 per 1000, respectively) and lowest in Central and Northern regions (13.7 and 13.5 per 1000, respectively). The prevalence of couples testing positive for β-thalassemia was 18.5 (18.0 for carriers and 0.5 for cases) per 1000 persons examined. The prevalence was highest in the Eastern region (59.0), moderate in the Southern, Western and Central regions (14.2, 10.2, and 10.1 per 1000, respectively) and lowest in the Northern region (3.9).

CONCLUSION

Vast regional differences in hemoglobinopathies among adult Saudis are being reported that may help policy makers better allocate resources of available preventive programs.

Growth in children and adolescents with sickle cell disease in Yemen

BACKGROUND

Physical growth is known to be impaired in children with sickle cell disease (SCD) and the prevalence and severity vary with geographical location. The factors which contribute to this sub-optimal growth are poorly understood.

OBJECTIVES

To describe the growth status of children and adolescents with SCD in Yemen using the new WHO reference values and to assess correlation of growth indicators with disease severity and with haematological and biochemical parameters.

METHODS

A cross-sectional study of children <16 years with SCD was conducted at Al-Wahda General Teaching Hospital, Aden. Anthropometric measurements of weight, length/height, mid-upper-arm circumference (MUAC) and body mass index (BMI) were collected. Disease severity was assessed using a severity index (SI) score.

RESULTS

A total of 102 children (56 male) were included and their mean age was 7.2 years (range 6 months to 15 years). Low weight, height and BMI-for-age Z-scores (<-2 SD) were observed in 45%, 54% and 35% of children, respectively. Regression analyses indicated an association of low height-for-age with male gender (p=0.02), low weight-for-age and weight-for-height with increased age (both p<0.001), low weight-for-age with raised alkaline phosphatase (p=0.04), and low BMI with reduced plasma albumin (p=0.04). There was no correlation between growth deficits and SI or anaemia severity.

CONCLUSION

Growth is severely impaired in children and adolescents with SCD in Yemen. Growth monitoring and nutritional support should be included in their comprehensive care package.

Growth and nutritional status of children with homozygous sickle cell disease

BACKGROUND

Poor growth and under-nutrition are common in children with sickle cell disease (SCD). This review summarises evidence of nutritional status in children with SCD in relation to anthropometric status, disease severity, body composition, energy metabolism, micronutrient deficiency and endocrine dysfunction.

METHODS

A literature search was conducted on the Medline/PUBMED, SCOPUS, SciELO and LILACS databases to July 2007 using the keywords sickle cell combined with nutrition, anthropometry, growth, height and weight, body mass index, and specific named micronutrients.

RESULTS

Forty-six studies (26 cross-sectional and 20 longitudinal) were included in the final anthropometric analysis. Fourteen of the longitudinal studies were conducted in North America, the Caribbean or Europe, representing 78.8% (2086/2645) of patients. Most studies were observational with wide variations in sample size and selection of reference growth data, which limited comparability. There was a paucity of studies from Africa and the Arabian Peninsula, highlighting a large knowledge gap for low-resource settings. There was a consistent pattern of growth failure among affected children from all geographic areas, with good evidence linking growth failure to endocrine dysfunction, metabolic derangement and specific nutrient deficiencies.

CONCLUSIONS

The monitoring of growth and nutritional status in children with SCD is an essential requirement for comprehensive care, facilitating early diagnosis of growth failure and nutritional intervention. Randomised controlled trials are necessary to assess the potential benefits of nutritional interventions in relation to growth, nutritional status and the pathophysiology of the disease.

Hereditary red blood cell disorders in middle eastern patients

Hereditary disorders of erythrocytes are common in many areas of the world, including the Middle East. In some regions of the Middle East more than 10% of the population are carriers of a gene for one of these conditions. When patients from the Middle East seek medical care in the West, an unrecognized but clinically important erythrocyte disorder can result in serious complications during routine medical care, such as a drug-induced hemolytic crisis. This article reviews the most important and most common inherited red blood cell disorders in Middle Eastern patients, including glucose-6-phosphate dehydrogenase deficiency, the thalassemias, and sickle cell disorders. We discuss when to suspect such conditions, how to determine their presence, and how to avoid potential complications related to them. Although a detailed discussion of treatment of erythrocyte disorders is beyond the scope of this article, some general management principles are described.

Osteomyelitis in sickle cell haemoglobinopathy with elevated fetal haemoglobin

The prevalence rate and characteristics of osteomyelitis in children below 15 years of age were studied in a population characterized by a high prevalence of sickle cell disease (SCD) with elevated fetal haemoglobin (HbF). All children born in our institution routinely undergo a haemoglobinopathy screening test. Osteomyelitis developed in 25 children (16 boys and nine girls) with a mean age of 5.5 years. Fourteen had sickle cell disease (SCD) and 11 had no haemoglobinopathy. The prevalence of osteomyelitis in children with SCD was 69 times higher than in those without (283 vs 4/10(5)). All 14 children with SCD and osteomyelitis also had elevated HbF. Three children had HbS alpha-thalassaemia, with mean HbF 24% and HbS 68.6%. Eleven children had sickle cell anaemia with elevated HbF, mean HbF 31.7% and HbS 66.7%. There was no significant difference in symptoms, signs, leucocyte, neutrophil and band counts, nor in sedimentation rates. Salmonella organisms were significantly more frequently responsible for osteomyelitis in SCD. The presence of elevated HbF in children with SCD should not lead to complacency as they are still at increased risk of developing osteomyelitis.

Sickle cell anaemia in Jordan and its clinical patterns

Homozygous sickle cell anaemia (SCA) is an inherited red blood cell disorder in which haemoglobin A is replaced by haemoglobin S. The disease exhibits a wide spectrum of clinical behaviour which has been well described in neighbouring countries. In Jordan, however, the disease has never been characterized. We used reviews of patients' notes and clinic interviews at Princess Badi'a Teaching Hospital, Irbid, Jordan to describe the clinical presentation of the disease in our area. The total number of patients was 41 (28 boys and 13 girls) and the median age was 9 years (range 1.5-21). The median age at presentation was 2.5 years (range 0.5-11). The commonest presenting feature was pallor (62%). An unusual feature of the disease in this series is the presence of a palpable spleen in 44% of patients older than 8 years. Associated G6PD deficiency was present in 29% of boys. Different clinical patterns of SCA were observed. Haemoglobin F is unlikely to be an explanation for this variability since it has not been shown to correlate with a number of severity indices of the disease such as the frequency of blood transfusions, hospitalizations and painful crises. Although the disease haplotype is not known in Jordan, our geographical location between Asia and Africa may suggest the presence of more than one haplotype and consequently different clinical patterns.

Sickle cell anaemia in Saudi-Arabian children

Forty-one Saudi Arabian children aged between six months and 13 years had a total of 68 admissions for complications of sickle cell anaemia during 1992. Review of their in-patient records and the relevant out-patient notes revealed a change in the clinical profile as compared to previous years. Hand-foot syndrome is virtually non-existent and vaso-occlusive crisis remains the commonest cause of admission. Introduction of pneumococcal vaccine and prophylactic oral penicillin has had no effect on the frequency of admissions and the admission rate per patient year. We have not seen any septicaemia/meningitis due to pneumococci. No death occurred during 1992.

The patterns of oropharyngeal microflora in patients with homozygous sickle cell disease

A controlled prospective study was carried out between 16 July 1991 and 31 January 1992 to evaluate the oropharyngeal flora in homozygous sickle cell disease (SS). Throat swabs for cultures were taken from 163 asymptomatic SS patients attending sickle cell clinics (90 children and 73 adults). Throat swabs were also taken from 84 asymptomatic healthy individuals as a control group (44 children and 40 adults). Group A beta hemolytic Streptococci were isolated from 16.6% of children with SS compared to 4.5% of children without SS (P<0.05). Staphylococcus aureus was isolated from 16.4% of adults with SS compared to 0% of adults without SS (P<0.0001). Group G beta hemolytic Streptococci and nongroupable Streptococci were also isolated from 11% and 13.7% of adults with SS compared to 0% and 2.5% of adults without SS respectively. Several other organisms were isolated only from SS patients. We conclude that the oropharyngeal flora of patients with SS is disturbed. This disturbance may contribute to morbidity of these patients.

Comprehensive newborn screening program: ARAMCO experience, the national need and recommendations

Comprehensive screening programs for congenital diseases of newborn infants are lacking at a national or regional level. A comprehensive newborn screening program modified to the needs and resources available was established in ARAMCO Dhahran Health Center. This program includes screening for congenital hypothyroidism, phenylketonuria, abnormal hemoglobins, glucose-6-phosphate dehydrogenase deficienc, and blood group incompatibilities. Several problems were encountered during the operation which required several modifications of the program. The organization and procedures of the program are described. Since the program was started in 1980, more than 70,000 newborn infants have been screened. Valuable epidemiological data have been collected and necessary information for direct clinical use was obtained. A national program to screen all neonates in the Kingdom of Saudi Arabia is achievable and urgently needed. Recommendations based on ARAMCO experience are given.

Variability of sickle cell disease in the Eastern Province of Saudi Arabia

The clinical and hematologic features of sickle cell disease in two groups of patients of different ancestral origin, but living in the Eastern Province of Saudi Arabia, are presented. Twenty-eight patients of southwestern origin were matched for gender, age, and diagnosis with an equal number of patients of eastern origin. The disease was diagnosed in all patients at birth, and follow-up study was done on a regular basis. Despite being born and living in the same environment (Eastern Province), patients of southwestern origin had more severe clinical features, consistently lower hemoglobin levels, and higher reticulocyte counts, suggesting more severe hemolysis. We conclude that there are at least two distinct forms of sickle cell disease in the Eastern Province of Saudi Arabia and that the variability of the disease in early childhood is more likely related to genetic than to environmental factors.

Acute splenic sequestration crises in Saudi children with sickle cell disease

Sickle cell disease (SCD) is a common disease in the Eastern Province of Saudi Arabia. Twenty per cent of the population have sickle cell trait and 1.75% have SCD. In the first 2 years of life, infection, hand-foot syndrome and acute splenic sequestration crisis (ASSC) are the most common complications of this disease. The classical characteristics of an ASSC, the subject of this paper, are sudden and rapid enlargement of the spleen, secondary to the massive pooling of red blood cells in the splenic sinusoids in a functioning spleen. Less common minor attacks of ASSC have been described recently. An ASSC is one of the most common causes of death in infants with SCD. The underlying cause and the precipitants of attacks of ASSC remain unknown. Seventeen children with ASSC were seen. Clinically, they had minor ASSC; three developed hypersplenism and four underwent splenectomy for recurrent attacks of ASSC. None of these 17 children had the classical ASSC described in black children where peripheral circulatory shock is encountered.

The immunological profile in sickle cell anaemia: a study of patients in the Arab Peninsula

Recurrent and often serious infections are common in sickle cell anaemia. The predisposing causes are multiple, and immune abnormalities are frequently blamed. In this study, immune complexes, lymphocyte subpopulations, immunoglobulins and complement were determined in 40 Arabs with sickle cell anaemia to ascertain some aspects of their immunological profile. Immunoglobulins were found to be either normal or high, C3 and C4 values mostly clustered at the lower level of normal with a few values below normal, and some patients had low T4/T8 lymphocyte ratios. The results are discussed and compared with previous studies.

Hypersplenism in homozygous sickle-cell disease in Saudi Arabia

Black children with homozygous sickle-cell disease usually have anatomic asplenia by 6-8 years of age. In the Eastern Province of Saudi Arabia, sickle-cell disease runs a benign course. Here we report six sicklers with hypersplenism as manifested by 1: splenomegaly (6/6); 2: persistent thrombocytopenia (6/6); 3: increasing severity of anaemia with the need for repeated blood transfusion (5/6); 4: leukopenia (1/6); 5: high reticulocyte count (6/6); 6: circulating nucleated red blood cells (5/6). All improved after splenectomy, with resolution of the thrombocytopenia and leukopenia, improvement in the degree of anaemia, decrease in the reticulocytes and disappearance of circulating nucleated red blood cells.

Delay in the fetal globin switch in infants of diabetic mothers

In the normal fetus, a switch from production of hemoglobin F (alpha 2 gamma 2) to hemoglobin A (alpha 2 beta 2) occurs at 28 to 34 weeks of gestation. In the fetus with beta-hemoglobinopathy or beta-thalassemia, this switch proceeds despite the morbidity that results when production of beta-globin is abnormal or reduced. Since insulin has recently been shown to induce renewed expression of some inactive genes, we studied globin biosynthesis during the natural evolution of the fetal globin switch under conditions of hyperinsulinemia, which occurs in infants of diabetic mothers. Such infants develop in a hyperglycemic environment, which produces reactive hyperinsulinemia. The normal increase in beta-globin production from pre-switch levels did not occur in 9 of 10 such infants at term, as compared with 11 normal infants, in whom the switch occurred by 36 to 39 weeks of gestation (P less than 0.0001). The delay in the switch from gamma-globin to beta-globin in this unique clinical setting may allow identification of physiologic factors that can modulate developmental gene suppression.

Splenic function in Saudi children with sickle cell disease

Splenic function was studied in 15 Saudi children with homozygous sickle cell disease. Age range was 4-13 years. Using 99Tc liver spleen scan, it was shown that 13 patients had some splenic function ranging from minimal to normal. This is in contrast to the black sicklers who usually have anatomic asplenia by the age of six to eight years. It might contribute to the relatively mild course in children with sickle cell disease in the eastern province of Saudi Arabia.

Neonatal screening for sickle cell disease in the Eastern Province of Saudi Arabia

Neonatal screening for sickle cell disease has been established in three hospitals in the Eastern Province of Saudi Arabia. In the first 17 months of this programme, 5630 cord blood samples were screened with the detection of 47 babies with an FS phenotype. The sickle cell trait occurred in 4.4% births in Al Khobar, in 6.7% in Dammam and in 17.9% in Qatif. An apparent excess of the FS phenotype over that predicted from the observed S gene frequency occurred at all three centres. The cause of this excess remains unknown although a high prevalence of sickle cell-beta o thalassaemia and the effects of non-random mating may be contributory factors.