Sickle cell anaemia in Sudan: clinical findings, haematological and serum variables

Sickle cell disease in Middle East Arab countries

The sickle cell (HbS) gene occurs at a variable frequency in the Middle Eastern Arab countries, with characteristic distribution patterns and representing an overall picture of blood genetic disorders in the region. The origin of the gene has been debated, but studies using β-globin gene haplotypes have ascertained that there were multiple origins for HbS. In some regions the HbS gene is common and exhibits polymorphism, while the reverse is true in others. A common causative factor for the high prevalence and maintenance of HbS and thalassaemia genes is malaria endemicity. The HbS gene also co-exists with other haemoglobin variants and thalassaemia genes and the resulting clinical state is referred to as sickle cell disease (SCD). In the Middle Eastern Arab countries, the clinical picture of SCD expresses two distinct forms, the benign and the severe forms, which are related to two distinct β-globin gene haplotypes. These are referred to as the Saudi-Indian and the Benin haplotypes, respectively. In a majority of the Middle Eastern Arab countries the HbS is linked to the Saudi-Indian haplotype, while in others it is linked to the Benin haplotype. This review outlines the frequency, distribution, clinical feature, management and prevention as well as gene interactions of the HbS genes with other haemoglobin disorders in the Middle Eastern Arab countries.

Evaluation of the particle gel diffusion technique for the detection of haemoglobin S in Sudanese patients

BACKGROUND

Sickle cell disease is a heterogenous disorder characterized by an abnormal haemoglobin and sickling phenomena of red cells. It is prevalent among certain nomadic tribes in Sudan. Painful, aplastic and haemolytic crises mark sickle cell anaemia. Haemoglobin S (HbS) is detected using haemoglobin electrophoresis, iso-electric focusing and/or high-performance liquid chromatography techniques with high sensitivity, but entails cost and expertise. This study aimed to determine the sensitivity, specificity and positive predictive values (PPV) of the ID-particle gel diffusion technique for screening, diagnosis and phenotyping of HbS in patients with a provisional diagnosis of abnormal haemoglobin.

METHODS

Following informed consent, 100 sequential individuals who reported to a central referral haemoglobinopathy clinic were enrolled. ID-particle gel diffusion technique was compared with cellulose acetate electrophoresis to determine haemoglobin phenotypes.

RESULTS

The ID-particle gel test detected HbAA with 100% sensitivity and 100% specificity. Sensitivity for HbS was 100%, whether as HbSS or as a mixed pattern. HbSS was identified in all cases where this is the only haemoglobin present. Other patterns were detected with <100% specificity and these would require further testing by other means to definitively identify abnormal haemoglobins.

CONCLUSIONS

Although the ID-particle technique is a simple and cheap technique with high sensitivity, specificity and PPV compared with cellulose acetate electrophoresis in detecting HbSS, it could not differentiate HbAS from HbSS with high levels of HbF. High environmental temperatures could melt the test microtubes. Cellulose acetate electrophoresis remains the technique of choice for the screening of abnormal haemoglobins in the Sudan.

Pharmacological studies on siculine syrup. II: effects on smooth, skeletal and cardiovascular muscle preparations

Earlier pharmacological screening showed that siculine syrup (a traditional herbal remedy purported to be useful in the prevention and treatment of sickle cell pain - crises, due to sickle cell anaemia - SCA) had antisickling and analgesic activities as well as antimicrobial and diuretic effects. SCA is an important haemoglobinopathy in Africa and many other communities/countries worldwide, with relatively high morbidity and mortality. The present study was to determine the effects of the extract on various isolated muscle preparations - smooth, skeletal and cardiovascular. Siculine (4-20 microg/mL), like acetylcholine (40-400 microg/mL), contracted the isolated rat uterus concentration dependently. Similar effects were observed with the guinea-pig ileum and rabbit jejunum (2-20 microg/mL). In contrast to these effects, the direct (muscle) and indirect (nerve) stimulations of rat phrenic nerve-diaphragm were relaxed by siculine (4 and 8 microg/mL) and d-tubocurarine (0.8 microg/mL). Siculine also concentration-dependently decreased both the rate and force of contraction of guinea-pig atria and rabbit heart and also resulted in a fall in cat blood pressure in a manner similar to those of acetylcholine. The possible therapeutic and/or toxicological consequences of these effects including the hypotensive activity is noteworthy since siculine syrup is used by the local population for the prevention and treatment of sickle cell pain crises.

Serum calcium and vitamin D status of patients with sickle cell disease in Curaçao

We measured parameters of calcium homeostasis and vitamin D status in HbSS patients (median age 8 years, range 3-19; 8 females, 10 males) and matched HbAA controls living in the tropical island of Curaçao. Serum calcium concentration in HbSS patients [2.32(0.07)mmol/L] was lower (ANCOVA, P = 0.002) than that of HbAA controls [2.44(0.14)]. None of the subjects had hypocalcaemia. There were no differences in serum concentrations of phosphate, total protein, albumin, intact parathyroid hormone (PTH), 25-hydroxyvitamin D [87(27) nmol/L in patients, 86(15) nmol/L in controls) and 1,25-dihydroxyvitamin D. There were no significant relations between PTH and 25(OH)D. We conclude that vitamin D status of HbSS patients in Curaçao is adequate.

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.

Increased activity of 5' nucleotidase in serum of patients with sickle cell anaemia

Fifty-nine patients with homozygous sickle cell anaemia, 17 heterozygous individuals and 22 controls were investigated in respect to serum (S) 5'nucleotidase (5'NT, EC 3.1.3.5). The patients showed a significantly higher mean value of S-5'NT compared to the controls. However, this rise was heterogeneous as it occurred only among a subgroup of patients. The heterozygous individuals were not different from either the patients or the controls generating a situation which puts the heterozygous individuals in an intermediate position between the patients and the controls. S-5'NT showed significant correlation with S-bilirubin, S-aspartate aminotransferase, S-alanine aminotransferase and especially S-gammaglutamyl transferase. However, it was not correlated with S-alkaline phosphatase, which is another marker for hepatobiliary disease. These results suggest that the liver involvement in a subgroup of patients with sickle cell anaemia is a mixture of hepatocyte damage and the biliary tree involvement.

Increased membrane activity of glyceraldehyde 3-phosphate dehydrogenase in erythrocytes of patients with homozygous sickle cell anaemia

Membrane-bound glyceraldehyde 3-phosphate dehydrogenase activity was measured in erythrocytes from 43 patients with sickle cell anaemia, 24 heterozygous and 27 controls. A significant increase of the activity was found among the patients but no such difference was observed between the heterozygous and the control individuals. The patients showed nearly non Gaussian distribution of the enzyme activity and were subgrouped on the basis of these results, subgroup I had normal values and subgroup II showed markedly increased activities. The patients in subgroup II had significantly lower blood haemoglobin concentrations and significantly higher lactate dehydrogenase activities in serum than subgroup I. The subgroups did not differ in blood reticulocyte counts, serum bilirubin, serum iron concentrations or band 3 protein content of erythrocyte membranes.