Evaluation of sociodemographic, clinical, and laboratory markers of sickle leg ulcers among young nigerians at a tertiary health institution

Background

Sickle leg ulcer (SLU) is a chronic and debilitating complication of sickle cell disease (SCD) associated with huge physical and psychosocial discomfort. The occurrence of SLU has remained steady despite successful preventive strategies and advances in SCD care. Although multifactorial factors have been implicated in SLU, these are not fully understood, and data on how these relate to young Nigerian SCD patients are scanty.

Aims

This study aims to evaluate the sociodemographic, clinical, and laboratory markers of SLU in a young Nigerian SCD cohort.

Patients and Methods

This study involved 109 young SCD patients and 67 healthy peers. The sociodemographic and laboratory parameters of the participants were examined in addition to the evaluation of the SCD cohort for SLU.

Results

Only the HbSS patients had SLU. This was found in six of them giving a prevalence of 5.9% (6/101). Their median age was 17, range 14-21 years. There was a preceding history of trauma in 4 (66.7%), and this included a case of traditional scarifications for local therapeutic purposes. Two of the three (66.7%) males with SLU also had priapism (P = 0.0132). Patients with SLU were older, had less frequent bone pain crises, and significantly belonged to the low socioeconomic class (P < 0.05). Although patients with SLU had relatively higher lactate dehydrogenase, platelet count, aspartate transaminase, bilirubin, white blood cell, and lower Hb concentration and HbF, these did not attain statistical significance (P > 0.05).

Conclusion

This study confirms that SLU is common among young SCD patients with HbSS genotype, low socioeconomic background, and older age. It also suggests that SLU could be more related to hemolysis-associated SCD phenotypes among the patients.

Sickle cell disease clinical phenotypes in children from South-Western, Nigeria

BACKGROUND

The clinical phenotypes of children with sickle cell disease (SCD) are poorly described in many sub-Saharan countries including Nigeria.

OBJECTIVES

The objective was to highlight various clinical phenotypes of SCD in children and investigate the influence of sociodemographic indices on the development of SCD complications.

METHODS

We carried out a cross-sectional study of 240 pediatric patients attending the sickle cell clinic and the emergency room in a teaching hospital in South-Western Nigeria over a 12-month period. The clinical phenotypes and severity of the disease were documented, and the influence of sociodemographic variables was investigated.

RESULTS

The five leading clinical phenotypes in our patients were significant pain episodes, that is, vaso-occlusive crisis in 159 (66.3%); anemic crisis in 62 (25.8%); severe bacterial infections, 57 (23.8%); acute chest syndrome (ACS), 27 (11.3%) and stroke, 7 (2.9%). Forty-two (33.1%) had a previous history of dactylitis (hand-foot syndrome). Other clinical phenotypes such as avascular necrosis of the femur, 4 (1.7%); nephropathy, 2 (0.8%); priapism, gallstone and chronic leg ulcer, one (0.4%) each, were not commonly seen. More children with a history of asthma had ACS. Furthermore, high steady-state white blood cell count was associated with severe disease.

CONCLUSION

The clinical phenotypes of SCD in children from South-Western Nigeria are highly variable with the disease manifesting very early and about 10% having significant complications. Sociodemographic characteristics appear to have little influence on the development of SCD complications among our patients, but age and low-socioeconomic class are associated with anemic crisis.

Current sickle cell disease management practices in Nigeria

BACKGROUND

Although Nigeria has the highest burden of sickle cell disease (SCD) worldwide, there is still variable and poor utilisation of standard-of-care practices for SCD patients in the country.

METHODS

This was a questionnaire survey of doctors in some dedicated SCD clinics in Nigeria in order to document the facilities available and common management practices.

RESULTS

There were responses from 18 clinics based in 11 institutions. The number of patients being followed in each centre ranged from 15 to approximately 11 000. All clinics provided malaria prophylaxis and folic acid routinely to their patients. Only eight clinics prescribe penicillin prophylaxis. Eight prescribe hydroxyurea to patients who can afford it when indicated. All of the centres except three have electronic cell counters, but all had access to haemoglobin electrophoresis. Three had high-performance liquid chromatography machines installed but none was being routinely used. One institution had a functioning molecular biology laboratory. There is no official newborn screening programme in the country. All had access to microbiology and chemistry laboratories. Nine institutions had CT, six had MRI and three had transcranial Doppler facilities.

CONCLUSION

The care available for SCD in Nigeria is still suboptimal and there is an urgent need for concerted effort to tackle the problem, but to make a significant impact on the burden of the disease would require more focus at the primary care level. Some steps to achieving this are outlined.

Haptoglobin gene polymorphisms in sickle cell disease patients with different βS-globin gene haplotypes

OBJECTIVE

To investigate the prevalence of haptoglobin (Hp) gene alleles in Kuwaiti sickle cell disease (SCD) patients, who generally have a mild phenotype, and compare the pattern to Nigerian SCD patients whose SCD phenotype is more severe.

SUBJECTS AND METHODS

Hp genotyping was carried out in a group of 82 and 54 SCD patients from Kuwait and Nigeria, respectively, and appropriate Hb AA controls. The Hp genotyping was done using a PCR technique followed by agarose gel electrophoresis.

RESULTS

The frequency of the Hp-2 allele was 73.8% among Kuwaiti SCD patients, while the Hp-1 allele predominated among Nigerian patients (60.7%). However, the differences were not significant (p > 0.05) when the allele distributions were compared between Kuwaiti SCD and their AA counterparts or between Nigerian SCD and their AA controls. There was no association of Hp-2 allele with frequent vaso-occlusive crisis among the Kuwaiti SCD patients.

CONCLUSION

The distribution of Hp alleles appears to follow ethnic and geographical trends. Their role in the pathophysiology of pain crisis is not clear.

Chromosome 22q11.2 deletion presenting with immune-mediated cytopenias, macrothrombocytopenia and platelet dysfunction

OBJECTIVE

To report a case of chromosome 22q11.2 deletion presenting with large platelets, platelet dysfunction, immune-mediated thrombocytopenia and neutropenia, in addition to other features of the disease.

CASE PRESENTATION AND INTERVENTION

The patient presented in the neonatal period with tetralogy of Fallot, subtle dysmorphic features and thrombocytopenia. Fluorescent in situ hybridization analysis confirmed the diagnosis of chromosome 22q11.2 deletion. Further investigations showed immune thrombocytopenia and neutropenia in addition to reduced expression of platelet GPIb and abnormal platelet aggregation studies. CD4:CD8 ratio was reversed. His cardiac abnormality was successfully corrected surgically. He had mild recurrent bacterial infections. Recurrent epistaxis was becoming increasingly more severe, and he had cognitive developmental and speech delay. His serum calcium, phosphorus and parathormone have remained normal.

CONCLUSIONS

Immune thrombocytopenia can coexist with macrothrombocytopenia and platelet dysfunction in chromosome 22q11.2 deletion and may present with significant bleeding episodes.

HLA-DRB1 alleles in Hb SS patients with avascular necrosis of the femoral head

Strong associations have been established between various HLA alleles and different complications of sickle cell disease (SCD). Recently, the HLA-DRB1*03 allele was shown to be associated with susceptibility to stroke while the HLA-DRB1*02 allele may be protective. While stroke and silent brain infarcts (SBI) are unusual in Kuwaiti children with SCD, avascular necrosis of the femoral head (AVNFH) is quite common. The modulatory association factors must still be elucidated. An investigation of HLA-DRB1 alleles was carried out in a group of 68 Kuwaiti SS patients, of age 7-44 years, of whom 20 (29.4%) had AVNFH, confirmed by magnetic resonance imaging. A group of 167 apparently healthy age- and sex-matched individuals served as controls. Comparison of the HLA alleles between the whole SS group and the controls showed a significant over-representation of DRB1*01 (P < 0.01) and DRB1*10 (P < 0.05) in the patient group. No significant differences in the allele frequencies in the SS patients with or without AVNFH were observed. It therefore appears that the HLA-DRB1 locus does not play a significant role in the pathogenesis of AVNFH Kuwaiti patients.

Pulmonary function studies in Kuwaiti children with sickle cell disease and elevated Hb F

Conflicting ventilatory defects have been reported in children with sickle cell disease (SCD). In Kuwait, the disease is relatively mild with a low incidence of acute chest syndrome and other complications, presumably due to the Arab-Indian haplotype chromosomal background and elevated Hb F levels. There have been no previous studies of pulmonary function in patients with this haplotype. Pulmonary function test (PFT) was carried out on 28 steady state children with SCD (21 homozygous sickle cell (SS), seven S beta(o) thal) and two group of controls: 17 age- and sex-matched healthy children and 10 children with HbH disease. The charts of the SCD patients were reviewed for frequency of acute chest syndrome and vaso-occlusive crisis. The mean values of forced vital capacity (FVC) (83.2 +/- 11.9 vs. 91.2 +/- 11.7) and vital capacity (VC) (81.5 +/- 11.8 vs. 90.5 +/- 10.9) were significantly lower in the SS patients compared with healthy controls (p < 0.05). Similarly, these values were significantly lower than in those of the HbH group (p < 0.001 for VC and p < 0.01 for FVC). The mean forced expiratory volume in 1 s (FEV1) was lower in SS patients (86.4 +/- 11.5) compared with healthy controls (94.2 +/- 14.2), but the difference was not significant (p = 0.07). Also, the FEV1 was significantly lower in SS patients than in the HbH group (p < 0.001). There was no significant difference in the PFT parameters between SS patients with acute chest syndrome and those without. Although patients with frequent vaso-occlusive crisis had lower PFT parameters, the differences were not significant in comparison to those with infrequent crisis. This study revealed an early restrictive and obstructive pulmonary function pattern in steady state children with SCD. The finding also indicates that the changes of PFT parameters in SS patients could not be attributed to anaemia per se as patients with HbH who also have chronic anaemia did not show similar changes. This observation underscores the early occurrence of pulmonary involvement, even in patients with an otherwise relatively mild SCD.

Avascular necrosis of the femoral head in adult Kuwaiti sickle cell disease patients

While sickle cell disease (SCD) is generally mild in most Kuwaitis, because of their elevated fetal Hb levels, avascular necrosis of the femoral head (AVNFH) appears to be a common complication. It was recently documented in 26.7% of Kuwaiti children with SCD. There have, however, been no previous studies of adult patients. This is a 1-year study of consecutive, steady-state SCD patients seen in the hematology clinic of Mubarak Al-Kabeer Hospital. The patients' charts were reviewed for frequency of hospitalizations, any documented complications and steady-state complete blood count (CBC). MRI was performed using T1- and T2-weighted FATSAT sequences in coronal and axial planes with 4-mm-thick slices on a 1.5-tesla GE super-conducting magnet. Thirty-five patients were studied, consisting of 25 SS and 10 Sbeta(0)Thal patients aged between 17 and 44, with a mean age of 26.7 +/- 9.3 years. Seventeen (48.6%) had varying degrees of AVNFH; among the 70 hips examined, 29 (41.1%) were affected. Of the 17 patients affected, 11 (64.7%) were SS, while 6 (35.3%) were Sbeta(0)Thal. There were 14 (82.4%) males and 3 (17.6%) females (chi(2) = 8.6, p < 0.01). The mean age of those affected, 27.5 +/- 10.7 years, was not significantly higher than that of the unaffected (26.3 +/- 8.0 years). Eleven (64.7%) of those affected had a history of frequent vaso-occlusive crisis. No significant differences could be demonstrated in the mean CBC and Hb F values of the two groups; coexistent alpha-thal trait was not a factor in the SS group. Male gender was the only significant predisposing factor identified. While more patients with frequent vaso-occlusive crises were affected, the difference was not significant. AVNFH is, indeed, quite common among Kuwaiti SCD patients and there is a need for early institution of preventive and therapeutic protocols.

Silent brain infarcts in adult Kuwaiti sickle cell disease patients

Although overt stroke is a common complication of sickle cell disease (SCD), its incidence is very low in Kuwaiti patients. On the other hand, the prevalence of silent brain infarcts, which is reported to be about 17-20% in American patients, has not been documented in adult Kuwaiti patients. This is a 1-year study of consecutive, asymptomatic SCD patients seen in the hematology clinic of Mubarak Al-Kabeer Hospital. Patients with a past history of seizure or any other neurological abnormality were excluded. The patients' charts were reviewed for frequency of hospitalizations, any documented complications, and steady-state CBC. MRI was done with a 1.5-Tesla unit with super-conducting magnet. T1- and T2-weighted sagittal and axial sections and proton-density axial images were obtained in 5-mm-thick sections. Thirty-five patients were studied, made up of 25 SS and 10 Sbeta(0)Thal, aged between 17 and 44 years, with a mean age of 26.9 +/- 9.3 years. MRI findings consistent with infarcts were found in 7 (20.0%) patients-6 SS and 1 Sbeta(0)thal-with a mean age of 31.8 +/- 8.2 years, which was significantly higher (P < 0.05) than the mean age of the unaffected group (25.1 - 9.0 years). There were also no differences in the mean Hb, Hb F, or any other hematological parameter in the two groups. Among the affected 6 SS, 2 had co-existent alpha-thal trait. It is interesting that, while silent infarcts are prevalent in young American patients, it is in the older age group that they occur in Kuwaiti patients. Further studies are needed to investigate the factors modulating this heterogeneity.

Silent brain infarcts are rare in Kuwaiti children with sickle cell disease and high Hb F

Overt stroke is rare among sickle cell disease (SCD) patients in Kuwait. However, there are no previous studies of silent cerebral infarcts, which have been described in up to 20% of American children with Hb SS. We have carried out a prospective brain MRI study among otherwise normal SCD patients, who were consecutive patients seen in a 1-year period to document the prevalence of silent cerebral infarcts in children with sickle cell disease in Kuwait. Any patient with a previous seizure or other neurological abnormality was excluded. MRI was done with a 1.5 Tesla unit with super-conducting magnet. T1- and T2-weighted sagittal and axial sections and proton density axial images were obtained in 5-mm thick sections. The study group consisted of 30 (23 SS and 7 Sbeta(0)Thal) patients-19 males and 11 females-whose ages ranged from 6 to 17 (mean of 9.8 +/- 3.5) years. Hb F ranged from 11% to 35% with a mean of 22.8% +/- 5.7%. Only one patient, a 10-and-a-half-year-old boy with Hb SS, showed hyperintense signals in the parietal white matter, consistent with small infarcts, thus giving a prevalence of 3.3%. Silent brain infarcts are uncommon in our patients, and the protective factors remain to be fully elucidated.

Temporal sequence of splenic dysfunction in sickle cell disease

Sickle cell patients develop splenic dysfunction early in the course of their disease as shown by failure to visualize the organ on technetium-99m colloid scintigraphy. However, preliminary studies from our center have shown that, when the spleen is not demonstrable on colloid uptake, it may be visualized on technetium-99m heat-denatured RBC scintigraphy. With time, however, the spleen can no longer be visualized with both tests in many patients. We have studied 46 patients aged 2 to 16 years, which included 36 SS, 7 Sbeta(0) thal, and 3 SD. Eighteen (39.1%) had normal splenic colloid uptake (Group 1), 15 (32.6%) had partial uptake (Group 2), and 13 (28.3%) had absent uptake (Group 3). When the patients in Group 1 were compared to those in the two other groups, there was no significant difference in the mean age and Hb F values. However, the mean Hb of 10.2 g/dl in Group 1 was significantly higher than the value of 9.0 g/dl in the other two groups. In addition, 60% of the SS patients with normal uptake and 40% of those with partial or absent uptake had co-existing alpha-thal trait; the difference in this proportion is significant (chi(2) = 85, P < 0.0001). Heat-denatured RBC scintigraphy was carried out on five patients in Group 2, and the spleen was visible in all, while of 12 children in Group 3, the spleen was visible only in 4 patients. This study demonstrates that the phagocytic function of the spleen, which is tested by colloid uptake, is the first to be lost while the filtration function, tested by denatured RBC uptake, persists for much longer. This finding may have significant implications for the clinical symptomatology and therapeutic strategies of sickle cell disease.

Hemoglobin electrophoresis and hemoglobinopathies in Kuwait

OBJECTIVES

To analyze the results of hemoglobin electrophoresis (HE) in the routine laboratory of a tertiary hospital in Kuwait and to review the common types of hemoglobinopathies prevalent in the country.

METHODS

This was a prospective study of HE performed on 2,386 samples in Mubarak Al-Kabeer Hospital, which serves more than 30% of the population of Kuwait, from June 1997 to May 1998.

RESULTS

Of the 2,386 HE tests, only 561 (23.5%) had abnormal hemoglobin genotypes. The most commonly identified hemoglobinopathies were beta-thalassemia minor (14%), sickle cell trait (6%), sickle cell anemia (0.9%), S beta zero thal (0.8%) and S beta + thal (0.8%). Two rare hemoglobin variants, Hb DPunjab and Hb E, were encountered.

CONCLUSION

HE yielded only 23.5% abnormal results, thus indicating the need to streamline requests for the test. The test should be limited to patients with hematological and clinical features suggestive of hemoglobinopathies or to individuals with a positive family history.

Avascular necrosis of the hip in children with sickle cell disease and high Hb F: magnetic resonance imaging findings and influence of alpha-thalassemia trait

Avascular necrosis (AVN) of the hip is a common cause of morbidity in sickle cell disease (SCD). Its prevalence increases with age and predisposing factors include coexistent alpha-thalassemia trait, frequent vaso-occlusive crisis and a high hematocrit (Hct). SCD is relatively mild among Kuwaiti patients because of their elevated Hb F levels, but a subset exists with severe recurrent vaso-occlusive crises. We carried out a prospective magnetic resonance imaging (MRI) study of the hip in a group of patients being followed in the Pediatric Hematology clinics of Al-Mubarak and Al-Amiri Hospitals. The association of AVN with age, frequency of hospitalization, alpha-thal trait, steady-state Hb, Hct, Hb F, WBC and platelet counts was investigated. MRI was carried out with a 1.5-tesla GE unit with a super-conducting magnet. Thirty patients (19 males, 11 females) (23 SS and 7 SbetaThal) were studied. Their ages ranged from 6 to 17 years, with a mean of 9.8 +/- 3.5 years, and Hb F from 11 to 35% with a mean of 22.8 +/- 5.7%. Among the SS patients, 11 (47.8%) had coexistent alpha-thal trait (-3.7-kb deletion). A total of 8 (26.7%) patients (6 SS and 2 SbetaThal) had varying degrees of osteonecrosis of the hip. Four (36.4%) of the 11 SS patients with alpha-thal trait and 2 (16.7%) of those without alpha-thal trait had osteonecrosis. This difference is, however, not statistically significant (chi(2) = 0.3, p = 0.5). While there was also no significant difference in the mean age and hematological parameters (Hb, Hct, Hb F, WBC, platelets), the SS patients with osteonecrosis had a significantly higher number of hospitalizations for vaso-occlusive crisis in the preceding 3 years than those without osteonecrosis.

Frequency of the 677 C-->T mutation of the methylenetetrahydrofolate reductase gene among Kuwaiti sickle cell disease patients

Sickle cell disease (SCD) is relatively mild among Kuwaiti Arabs. However, an atypical subset of patients exists with frequent, severe vaso-occlusive crisis and osteonecrosis. The thermolabile variant of MTHFR, resulting from a C-->T mutation at nucleotide 677, has been shown to be associated with hyperhomocysteinemia, which is an important risk factor for premature vascular disease. We have screened an unselected group of 41 Kuwaiti SCD patients (33 SS and 8 Sbeta(0)-thal) attending the Hematology Clinic of Kuwait University Teaching Hospital for the MTHFR mutation, using a PCR-RFLP method. The patients were aged 2-41 years (mean of 12.8 +/- 8.6). One (2.4%) individual was homozygous for the mutation while 15 (36.6%) were heterozygous, giving an allele frequency of 20.7%. Twenty-one patients (14 SS and 7 Sbeta(0)-thal) were screened for osteonecrosis using MRI of the hip (spin-echo T1- and T2-weighted images). Seven (33.3%) had varying degrees of osteonecrosis, among whom the frequency of the 677 C-->T allele was 21.4%. The frequency was identical among those without osteonecrosis. Although the allele frequency is higher among our patients compared to American SS patients, our results do not suggest an association with osteonecrosis.

Influence of alpha-thalassemia trait on the prevalence and severity of anemia in pregnancy among women in Kuwait

Alpha-thalassemia is very common in the Kuwaiti population, but its influence on anemia of pregnancy has not been previously investigated. We have screened a group of 59 anemic (Hb < 11 g/dl) pregnant women for the alpha-thal-2 (-alpha-3.7 kb) deletion which is the commonest alpha-thal allele in this community, using a polymerase chain reaction method. A control group of 35 nonanemic (Hb > or = 11 g/dl) pregnant women was studied for comparison. All the women were in the second or third trimester of pregnancy. Among the 94 women in both groups, 69 (73.4%) had a normal complement of alpha-globin genes (alphaalpha/alphaalpha), 18 (19.1%) were heterozygotes (-alpha/alphaalpha) and 7 (7.4%) were homozygotes (-alpha/-alpha) giving an allele frequency of 17.0%. Among the anemic group, there were 44 (74.6%) individuals with a normal genotype, 9 (15.3%) heterozygotes and 6 (10.2%) homozygotes. In the nonanemic group, the corresponding prevalence figures were 25 (71.4%), 9 (25.7%) and 1 (2.9%), respectively. The difference between these distributions was statistically significant (chi2 = 37.5, p < 0.0001). However, the mean Hb values were similar in heterozygotes, homozygotes and normal individuals. We, therefore, conclude that while the alpha-thal trait affects the prevalence of anemia among pregnant Kuwaiti women, it does not affect its severity.

Th1 and Th2 cytokine profiles in sickle cell disease

We have investigated the levels of Th1 (IL-2 and IFN-gamma) and Th2 (IL-4) cytokines in the plasma and supernatants following peripheral blood mononuclear cell culture and mitogen stimulation in a group of 39 patients with sickle cell disease (SCD) made up of 29 SS, 8 Sbeta-thal and 2 Hb SD in steady state. Five SS patients were studied during 7 episodes of vaso-occlusive crisis. Twenty-four control (3 Hb AS and 21 Hb AA) were also studied; 10 were acutely ill while 14 were healthy at the time of the study. The plasma levels of IL-2 and IFN-gamma were similar in the patients and the controls. However, plasma IL-4 was significantly higher among the steady-state SS patients than in the controls. While there was no significant difference in cytokine levels following mitogen stimulation in the different groups, plasma IL-2 to IL-4 and IFN-gamma to IL-4 ratios were significantly lower among the steady-state SS patients, indicating a possible Th2 bias in our sickle cell patients and suggesting a possible mechanism to explain the predisposition of SCD patients to bacterial infections. However, SS patients with good splenic function showed a relative Th1 bias, which may be an additional explanation for the protection against bacterial infections in such patients.

Tumor necrosis factor-alpha is undetectable in the plasma of SS patients with elevated Hb F

Steady-state sickle cell disease (SCD) patients may have increased plasma levels of acute phase reactants and pro-inflammatory cytokines because of subclinical inflammation. We have estimated TNF-alpha levels in the plasma and in supernatants following peripheral blood mononuclear cell (PBMC) activation with phytohemagglutinin (PHA) in a group of Kuwaiti SCD patients using ELISA. The group consisted of 28 SS, 8 Sbeta-thal, and 2 SD patients all in steady state; 5 SS patients were studied during 7 episodes of painful crisis. The subjects were aged 2 to 16 years, with a mean of 7.3 +/- 3.5 years. The beta(S)-globin gene cluster haplotype, alpha-tha1 status, and spleen function were determined in the SS group using standard techniques. Most (82%) were homozygous for the Saudi Arabia/India haplotype and had elevated Hb F levels ranging from 15% to 35%. There were 24 controls (Hb AA or AS), of whom 14 were healthy and 10 were acutely ill at the time of the study. None of the children with SCD (either in steady state or crisis) had detectable plasma TNF-alpha, but four controls (3 acutely ill and one healthy) had levels ranging from 61.7 to 249.8 pg/mL. Following PHA stimulation most subjects responded with high levels of TNF-alpha, with the median level among the steady-state SS patients being significantly higher than that in the controls (both the acutely ill or healthy). It therefore appears that because of the mild disease among our Arab SS children, TNF-alpha is not detectable in their plasma in steady state; these children, however, had a significantly higher response than controls following PBMC activation.

GM-CSF in sickle cell anemia patients with elevated Hb F

We estimated plasma GM-CSF levels in a group of 28 steady-state sickle cell anemia (SS) patients in Kuwait, using an ELISA technique. There were 24 age-matched Hb AA controls, 14 of whom were healthy while 10 were acutely ill at the time of the study. Five SS patients were also studied during 6 episodes of painful crisis. Among the SS patients, 82.1% were homozygous for the Saudi Arabia/India (SAI) haplotype with Hb F ranging from 15 to 35% and total Hb from 8.5 to 11 g/dl. Three patients (siblings) were SAI/Benin compound heterozygotes with Hb F of 9-23% and total Hb >10 g/dl. One patient each was homozygous for the Benin or the Bantu haplotype; they had Hb F <2% and total Hb of 6.6 and 7.2 g/dl, respectively. Four (14. 3%) steady-state SS patients had detectable plasma GM-CSF ranging from 75 to 1,817.6 pg/ml. These included the 2 patients with Hb F <2. 0% and 2 with the SAI/Benin compound heterozygotes with Hb F of 11 and 9%, respectively. Four (66.7%) SS patients in crisis, 6 (42.9%) healthy controls and 6 (60%) acutely ill controls had detectable plasma GM-CSF. A clearcut association of GM-CSF with Hb F level or degree of anemia in steady-state SS patients could not be established. The appearance of GM-CSF in the plasma of patients in crisis and also among control subjects raises the possibility that other factors are involved in the production of this cytokine in the subjects studied.

A comparative study of perception of sickle cell anaemia by married Nigeria rural and urban women

Environmental factors may influence perception of or attitude to chronic disorders. The perception of sickle cell anaemia (SCA by 165 married Nigerian rural and 507 urban women was studied to determine how living in an urban or rural environment may influence perception. None of the subjects had children with SCA. The instrument used for data collection was a structured questionnaire designed to enquire into their knowledge about the cause, precipitating factors for crises, clinical features of SCA and their opinions regarding traditional and modern treatment options for the disorder. As a group, urban women had better knowledge about SCA than rural women probably because their social environment afforded a wider scope for interaction with and information exchange among people. For most respondents, the educational institutions attended the health institutions in the locality and the electronic media were poor sources of information on SCA. The study showed a serious lack of information about important aspects of SCA among rural women. We think the training of primary health care providers as counsellors on SCA, the inclusion of instruction about SCA in the curriculum of schools and sustained outreach programmes on SCA on the electronic media would ensure early education of people in both rural and urban communities and help to improve perception of the disorder.

Influence of alpha-thalassemia on cholelithiasis in SS patients with elevated Hb F

Chronic hemolysis, with consequent hyperbilirubinemia, predisposes SS patients to pigment gallstones. The other factors which influence the development of stones in these patients have not been identified. We have carried out a combined prospective and retrospective study of SS patients in Kuwait and specifically investigated the influence of coexistent alpha-thal trait on the prevalence of gallstones. A total of 45 patients (30 males, 15 females) with ages ranging from 1 to 16 years (mean 7.2 +/- 3.1) were studied. Most were either homozygotes for the Saudi Arabia/India haplotype (86.7%) or compound heterozygotes for this and the Benin haplotype (11.1%). They were screened for gallstones with ultrasonography. alpha-Globin genotypes were determined using a combination of PCR and allele-specific oligonucleotide hybridization techniques to identify the common alpha-thalassemia alleles in this population. Gallstones were detected in 7 (15.6%) patients (4 males, 3 females), whose mean age (10.5 +/- 5.5 years) was significantly higher than that (6.8 +/- 3.2 years) of those without stones (p < 0.01). The mean total Hb of the former (8.4 +/- 0.8 g/dl) was also significantly (p < 0.05) lower than in the latter (9.5 +/- 1.3 g/dl), while the difference in mean Hb F levels was not significant. None of the 4 alpha-thal homozygotes had gallstones while 2 of 13 heterozygotes and 5 of the 23 patients without coexistent alpha-thal had. The differences in these proportions are statistically significant (chi2 = 20.4, p < 0. 001). It therefore appears that coexistent alpha-thal decreases the chance of developing gallstones in Arab SS patients. This may be related to less hemolysis in such patients as shown by their higher mean Hb level.

Alpha-, beta-, and gamma-mRNA levels in beta-thalassemia; transcriptional and translational differences in heterozygotes, homozygotes, and compound heterozygotes

We have determined the relative levels of alpha-, beta-, and gamma- (G gamma- and A gamma-) mRNAs in the reticulocytes of patients with mild beta-thalassemia intermedia due to combinations of promoter mutations and a classical type of beta-thalassemia, as well as in their relatives. The expected differences in the alpha/beta-mRNA ratio confirmed the mild suppression of beta-mRNA synthesis, particularly in heterozygotes for the -101 (C-->T) promoter mutation and the large increase in the relative gamma-mRNA level in compound heterozygotes. A significant discrepancy between Hb F and gamma-mRNA levels, observed in previously published studies, was confirmed indicating a less efficient gamma-mRNA translation. When the two different gamma-mRNA (G gamma- and A gamma-) levels were determined it was observed that in beta-thalassemia heterozygotes the extra gamma-mRNA was primarily of the G gamma type suggesting a more efficient translation of the A gamma-mRNA. This difference disappeared in homozygotes and compound heterozygotes: both mRNAs (G gamma- and A gamma-) translate with an equal efficiency.

Variability in the fetal hemoglobin level of the normal adult

We analyzed blood samples from more than 200 normal adults, and quantified their Hb F by cation-exchange high-performance liquid chromatography. In several subjects with slightly elevated Hb F (0.4-4.3%), we determined the Ggamma levels in the Hb F and DNA sequence variations in the locus control region II and in the Ggamma and Agamma promoters. About 25% of the approximately 200 normal teenaged high school students had elevated Hb F; detailed analyses of some 20 students, selected at random, identified most as females with a homozygosity for the C-->T variation at position -158 (Ggamma). One 11-year-old boy was heterozygous for the A-->G change at position -161 (Ggamma); he and two of his relatives had approximately 4% Hb F, high Ggamma values, and a high level of (mainly) Ggamma-mRNA. Nearly 40 normal adults from Macedonia and from Georgia (mostly Caucasians) were tentatively identified as Swiss HPFH heterozygotes because slightly elevated Hb F levels were observed at least once. Many of these persons were heterozygous or homozygous for the C-->T mutation at -158 (Ggamma), and a few carried a gamma-globin gene triplication. The C-->T change appears to be an important factor predisposing the adult to increased Hb F production. Evidence suggests a gene dose effect in (mildly) anemic adults; however, other factors besides the C-->T change at -158 (Ggamma), including factors not linked to the beta-globin region, may cause an increase in gamma-chain synthesis.

Influence of alpha-thalassemia trait on spleen function in sickle cell anemia patients with high HbF

Spleen function was studied in a group of 20 Kuwaiti SS patients (aged 2-12 years), using 99mTc-labeled tin colloid scintigraphy. They were screened for the alpha-thalassemia determinants which are prevalent in the Arabian Peninsula [-alpha (3.7 kb) deletion, alpha2-globin gene polyadenylation signal (AATAAA => AATAAG) mutation, and 5' IVS-I splice junction pentanucleotide (GAGGTGAGG => GAGG) deletion] with a combination of polymerase chain reaction and allele-specific oligonucleotide (ASO) hybridization techniques. The patients were divided into three groups depending on the result of their colloid uptake. Group I consisted of 7 patients (35.0%) with normally visualized spleens, Group II consisted of 5 (25.0%) with partial visualization, and in Group III there were 8 (40.0%) in whom the spleen was not visualized at all. The significant distinguishing features among those in Groups I and III were mean corpuscular volumes (MCVs) of 74.1 +/- 5.1 and 90.1 +/- 6.6 fl (P<0.0001) and mean corpuscular hemoglobins (MCHs) of 22.4 +/- 2.7 and 27.5 +/- 4.0 pg (P<0.05), respectively. The overall frequency of alpha-thalassemia determinants in the study was 35.0%; however, the frequencies in Groups I, II, and III were 57.1, 30.0, and 18.8%, respectively. alpha-Thalassemia trait, therefore, appears to be associated with normal splenic function in these patients.

The relative levels of alpha 2-, alpha 1-, and zeta-mRNA in HB H patients with different deletional and nondeletional alpha-thalassemia determinants

We have analyzed the alpha 2/alpha 1-, alpha/beta-, zeta/(alpha + zeta)-mRNA ratios in the retic-ulocytes of 40 patients with Hb H disease. 21 patients had deletional Hb H disease (- -/- alpha), namely combinations of one of four types of alpha-thal-1 (MED-I, MED-II, -(alpha)20.5, SEA) and one of two types of alpha-thal-2 (-3.7 or -4.2 kb); 13 had Hb H disease because of combinations of one of these alpha-thal-1 deletions with either a 5 nt deletion at the 5' splicing site of IVS-I, or a terminating codon mutation (Hb CS), or a poly(A) mutation, and six were homozygous for either a poly(A) mutation or the 5 nt deletion. Significant differences were observed between the deletional types (- -/- alpha; alpha 2/alpha 1 ratio of zero; alpha/beta ratio of approximately 1) and non-deletional types (- -/alpha T alpha; alpha 2/alpha 1 ratio of 0.05-0.3 for those with T = the 5 nt deletion or the terminating codon mutant, and approximately 1.0 for those with T = a poly(A) mutation; alpha/beta ratio in all types of approximately 0.7). Comparable data were found for the nondeletional alpha-thal-2 homozygotes. The noted differences were highly significant and the determination of the two ratios may be diagnostically of considerable value. The low alpha 2/alpha 1-mRNA ratio in the two patients with - -/alpha-5nt alpha and the one patient with alpha-5nt alpha/alpha-5nt alpha indicates the presence of minute amounts of alpha 2-mRNA; apparently splicing at the donor site is greatly impaired by this deletion but not eliminated. The high alpha 2/alpha 1-mRNA ratio in the four patients with - -/alpha PA-2 alpha and the five patients with alpha PA-1 alpha/ alpha PA-1 alpha (PA-1 and PA-2 are poly(A) mutations) is due to the presence of an elongated alpha 2-mRNA which uses an alternate location as polyadenylation site. The relative levels zeta-mRNA varied considerably; the highest levels were found in patients with the -(alpha)20.5/-alpha or - -SEA/-alpha deletional types but not in those with the -(alpha)20.5/alphaPA-2 alpha, -(alpha)20.5/alpha-5nt alpha, or - -SEA/alphaCS alpha nondeletional types. No definitive explanation can be given for these differences; perhaps certain sequences that are part of some of the alpha-thal-1 deletions are important for the suppression of the zeta-globin gene.

Co-inheritance of Hb D-Punjab (codon 121; GAA-->CAA) and beta (0) -thalassemia (IVS-II-1;G-->A)

PURPOSE

Homozygosity for Hb D-Punjab (or Hb D-Los Angeles; codon 121; GAA-->CAA) is rare among Arabs. The co-inheritance of Hb D with beta(0)-thalassemia trait is even rarer, with only 10 previous cases reported worldwide.

PATIENTS AND METHODS

We present clinical and hematological data for two Hb D homozygotes and three compound heterozygotes for Hb D-Punjab and beta(0)-thalassemia (IVS-II-1; G-->A). All the individuals belong to a consanguineous Kuwaiti Arab family. The hemoglobin variant and the beta-thalassemia allele were characterized by sequencing, allele-specific amplification, and oligonucleotide hybridization.

RESULTS

The hematology was unremarkable except for a moderate elevation of Hb F (3-4%) and significant hypochromia and microcytosis in the subject with Hb D/beta(0)-thalassemia.

CONCLUSION

This report confirms the benign nature of homozygosity for Hb D.

Globin mRNA in beta-thalassemia heterozygotes with different beta-thalassemia alleles and in heterozygotes for hereditary persistence of fetal hemoglobin

Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to determine the alpha 2/alpha 1-, alpha/beta-, and gamma/beta-mRNA ratios in subjects with beta-thalassemia (beta-thal), hereditary persistence of fetal hemoglobin (HPFH), and normal adults. The alpha- and beta-globin gene mutations were characterized with gene mapping, PCR, and DNA sequencing. The average alpha 2/alpha 1-mRNA ratio was the same in normal adults and beta-thal heterozygotes with four alpha-globin genes (2.61-2.63) or with an alpha-thal-2 trait (1.48-1.55). The average alpha/beta-mRNA ratios were 4.47 and 3.84 in normal adults with four alpha-globin genes and with alpha-thal-2 trait (-alpha/alpha alpha), respectively. There was an increase of approximately 50% in beta-thal heterozygotes with transcriptional mutants [-88 (C-->T) and -29 (A-->G)] with lower values (approximately 25%) in those with alpha-thal-2 trait (-alpha/alpha alpha). High alpha/beta ratios were also observed for heterozygotes for nonsense or frameshift mutants located in exon 1 or exon 2. Increases of approximately 150-165% were seen in subjects with RNA processing defects; an exception was the IVS-1-110 (G-->A) mutation with a normal value in the heterozygote. The increases were also less pronounced in heterozygotes for the codon (CD) 121 (G-->T) mutation and the CDs 134-137 insertion/deletion. Normal alpha/(gamma + beta) values were seen in 3 heterozygotes each with a different deletion involving part of the beta-globin gene. The presence of the silent beta-thal allele, -101 (C-->T), in trans to a CD 8 (-AA) allele has a minor effect on the alpha/beta-mRNA ratio. The alpha/beta-mRNA ratio in HPFH heterozygotes was approximately 145% of normal, but with a gamma-mRNA level of 35.4-44.7% the calculated alpha/(gamma + beta) ratio became as in normal adults. The RT-PCR methodology appears useful in expression studies in beta-thal (and HPFH) and values of mRNA appear to correspond to the type of prevailing mutation(s) and concomitant alpha-thal.

Morbidity, beta S haplotype and alpha-globin gene patterns among sickle cell anemia patients in Kuwait

Admission records of children with sickle cell anemia (SS), in the two main teaching hospitals in Kuwait, were reviewed for a 1-year period. The haplotypes of 92 beta s chromosomes (from 39 SS, 11 AS, 2 S beta-thalassemia [S beta-thal] and 1 SD individuals) were determined using an allele-specific oligonucleotide (ASO) hybridization technique, while the alpha-globin gene status of 27 SS and 33 AS individuals, i.e. 120 chromosomes, was determined with a combination of polymerase chain reaction and AS techniques. A vasooclusive crisis was the most common (60.0%) cause of hospitalization, followed by infections (20%). Hospital admissions were most common during the hottest month of the year (July). Few complications of the disease were seen among patients on follow-up; however, splenomegaly was present in 24.0%, hepatomegaly in 15.2%, gallstones in 15.2% and aseptic necrosis of the femoral head in 6.1%. Haplotype 31 (Saudi Arabia/India) is the most frequent in this community, being present in 80.4% of the chromosomes tested; Benin haplotype 19 was found in 12.0% and Bantu haplotype 20 in 6.5%. Hb F in the haplotype 31 homozygotes and heterozygotes ranged from 11.4 to 35.1% (mean 22.5 +/- 5.2%). The frequency of alpha-thal determinants in the study was 40.0%, the commonest being the -alpha 3.7-kb deletion (27.5%), the alpha 2 polyadenylation signal (AATAAA-> AATAAG) mutation (10.2%) and the IVS-I 5' end GAGGT-GAGG->GAGG pentanucleotide (5 nt) deletion (3.3%). SS patients with coexistent alpha-thal trait did not have severe recurrent infections and none had gallstones. The high frequencies of the Saudi Arabia/India beta s haplotype and alpha-thalassemia trait contribute to the mild nature of SS disease among Kuwaiti Arabs comparable to that in eastern Saudi Arabia.

Study of the molecular defects in pyruvate kinase deficient patients affected by nonspherocytic hemolytic anemia

We have examined DNA from fifteen unrelated pyruvate kinase deficient patients with hereditary nonspherocytic hemolytic anemia (HNSHA) for the molecular alterations responsible for the enzyme deficiency. All but 3 of the 30 putative mutations were identified. Fourteen different mutations were found. Nine were missense mutations: 320 T-->C, 823 G-->C, 1276 C-->T, 1378 G-->A, 1484 C-->T, 1529 G-->A, 1654 G-->A, 1675 C-->G; three were nonsense mutations: 603 G-->A, 721 G-->T, 1501 C-->T; one was an insertion at 1574 GGG-->GGGG and the other a three nucleotide in-frame deletion 391-392-393 ATC. Eight of these mutations have not been previously described. We also investigated all of the patients for the C/A polymorphism at nt 1705 and the microsatellite ATT repeat in intron 11. All of the mutations that had previously been reported by us (391-393del, 721T, 1484T, 1529A) were found in the context of the same haplotype as the earlier cases, supporting the concept that each may have a single origin.

Factors associated with hypochromia and microcytosis among high school students in the southeastern United States

We studied hematologic findings in 617 apparently healthy Georgia elementary, middle, and high school students, aged 10 to 19 years, and examined the influence of several parameters (race, sex, iron status, and genetic hemoglobin [Hb] abnormalities) on hypochromia and microcytosis, with or without anemia. Fourteen students (2%) (6 male, 8 female; 4 white, 10 black) were found to be anemic (Hb < 11.8 g/dL in boys or < 11.3 g/dL in girls). Hypochromia (mean corpuscular Hb < 25 pg) with or without microcytosis (mean corpuscular volume < 78 fL) was found in 26 students (4%). Iron deficiency was the main associated factor in white students, but in blacks genetic Hb abnormalities, especially alpha-thalassemia trait, were other predisposing factors. The overall prevalence of iron deficiency (serum ferritin < or = 12 ng/mL) was 32.4% in the entire sample population, 30.5%, among blacks, and 33.2% among whites.

Possible factors influencing the haemoglobin and fetal haemoglobin levels in patients with beta-thalassaemia due to a homozygosity for the IVS-I-6 (T-->C) mutation

We have collected haematological, haemoglobin (Hb) and DNA sequence data for 29 patients with a homozygosity for the IVS-I-6 (T-->C) mutation with the intention of identifying factors contributing to the observed variability in the severity of the disease. None of the patients had received blood transfusion therapy for at least 6 months prior to the study. Hb levels varied from 5.0 to 9.9 g/dl. Patients with high Hb F (more than 1.5 g/dl or > 20%) had high total Hb levels (7.5-9.7 g/dl) but some with low Hb F also had high total Hb levels; two had a concomitant alpha-thalassaemia-2 (alpha-thal-2) heterozygosity. An inverse correlation between the Hb F and Hb A2 levels was observed. The majority of the patients were homozygous for haplotype VI (49/58 chromosomes) but haplotypes IV (2/58) and VII (7/58) were also present. The only haplotype IV homozygote had high Hb F levels with high G gamma values and the C-->T mutation at position -158 in the G gamma promoter, while both high and low Hb F levels were observed among patients with haplotypes VI and VII. Analysis of sequence variations in regulatory regions included the 5' hypersensitive sites (HS) 4. 3 and 2 of the locus control region (LCR), the G gamma and A gamma 5' flanking regions, the second intervening sequence (IVS-II), and the 5' beta-globin gene region in two patients with high Hb F (one homozygote each for haplotypes VI and IV), and in two patients with low Hb F levels (one homozygote each for haplotypes VI and VII). Haplotype specific differences were observed in the LCR 5' HS-2 and in the G gamma and A gamma flanking and IVS-II regions; however, no differences were present between the low and high Hb F-producing haplotype VI chromosomes, suggesting a major role for factors which are not linked to the beta-globin gene cluster in mediating gamma-globin gene expression in patients with this type of beta-thal.

The in vivo expression of the globin genes of the beta cistron in gamma-, delta-, and delta beta-thalassemia heterozygotes

There is considerable evidence suggesting that the switch from gamma to delta and beta chain production after birth is due, in part, to silencing of the gamma genes by stage-specific factors which bind to their promoters and to the competition from the adult (delta and beta) genes for a common enhancer element located in the locus control region. As a consequence one can expect that the increased Hb F production in adults with hereditary persistence of fetal hemoglobin or delta beta-thalassemia is directed mainly by gamma-globin genes in cis to the deletion(s) responsible for these conditions. Here we review data on heterozygotes with gamma-, delta- or delta beta-thalassemia, who also had an A gamma T mutation, in cis or in trans, which was used as a marker of gamma gene expression. The results show that a deletion affecting adult beta genes favors the expression of gamma genes in cis, while the deletion of a single gamma gene does not affect the expression of the beta gene in cis but leads to a faster gamma-->beta switch postnatally.

Sickle cell anemia, sickle cell beta-thalassemia, and thalassemia major in Albania: characterization of mutations

We have analyzed the hemoglobin abnormalities in nearly 50 Albanian patients with a significant hemoglobinopathy and included 37 relatives in this study. Sickle cell anemia (SS) is a common disorder; all 15 sickle cell anemia patients had the complications expected for this disease. The beta S haplotype was type 19 (Benin); alpha-thalassemia-2 was rare. Three beta-thalassemia alleles (IVS-I-110, G-->A; codon 39, C-->T; IVS-I-6, T-->C) were present in nearly 85% of the beta-thalassemia alleles; their frequencies were intermediate between those observed in the populations of neighboring countries. A few rare mutations were also found, which might have originated in India, Turkey, Macedonia, and Greece. Nearly all patients with Hb S-beta-thalassemia had the IVS-I-110 (G-->A) mutation. The frequencies of 11 beta-thalassemia mutations in 17 mostly Mediterranean countries have been reviewed.

A novel deletion of approximately 27 kb including the beta-globin gene and the locus control region 3'HS-1 regulatory sequence: beta zero-thalassemia or hereditary persistence of fetal hemoglobin?

A novel deletion of approximately 27 kb with the 5' breakpoint 1.5 to 2.2 kb upstream of the beta-globin gene, and the 3' breakpoint approximately 24 kb downstream of the beta-globin gene, has been found in five members of two families from Southeast Asia (Vietnam and Cambodia). Six members of another family from China, previously reported from our laboratory, have also been shown to carry this deletion. The patients presented with mild hypochromia and microcytosis, a hemoglobin (Hb) A2 level of approximately 4.0%, and a markedly increased, heterocellularly distributed, Hb F level (14.0 to 26.0%). In vitro globin-chain synthesis showed a mild imbalance with appreciable gamma-chain compensation (alpha/beta + gamma ratio of 1.46). The 3' end of this deletion includes the 3'HS-1, and we hypothesize that removal of this region results in the loss of its gamma-globin gene-silencing effect, which causes a markedly elevated Hb F level with a modest increase in Hb A2 levels, unlike the situation in other deletional beta zero-thalassemias. The possible influence of particular sequence variations in the locus control region 5'HS-2 and the G gamma promoter, present on the chromosome with this deletion, on the overall gamma-globin gene should also be considered.

Molecular characterization of alpha-thalassemia determinants, beta-thalassemia alleles, and beta S haplotypes among Kuwaiti Arabs

Using amplification, allele-specific oligonucleotide (ASO) hybridization and DNA sequencing we have documented the molecular basis of 64 alpha- and 123 beta-thalassemia (thal) chromosomes, and the haplotypes of 18 beta S chromosomes from patients followed in three hospitals in Kuwait. Of the 30 chromosomes from 15 patients with Hb H disease, 26 (86.7%) carried the polyadenylation (poly A) signal mutation (AATAAA-->AATAAG) in the alpha 2-globin gene, 3 (10%) had the -alpha (3.7 kb) deletion, and 1 (3.3%) had the pentanucleotide deletion in the 5' IVS-I splice junction (alpha-5nt alpha). As many as 12 different beta-thal mutations were identified; 6 Mediterranean alleles [IVS-II-1 (G-->A), IVS-I-6 (T-->C), codon (CD) 39 (C-->T), IVS-I-110 (G-->A), CD 8 (-AA), and IVS-I-1 (G-->A)] were present in 79 (64.2%) of the chromosomes tested. Four East Indian alleles [IVS-I-5 (G-->C), IVS-I 3' end -25 nt deletion, CDs 8/9 (+G), and 619-bp deletion] were found in 31 (25%), and the two Kurdish/Iranian alleles [CD 44 (-C) and CDs 36/37 (-T)] were found in 13 (10.6%) chromosomes. Fourteen beta S chromosomes carried haplotype No. 31 (Saudi Arabia/India); 3 had haplotype No. 19 (Benin), and 1 was a hybrid with haplotype No. 31-specific characteristics in the locus control region hypersensitive site-2 (LCR-HS-2), and haplotype No. 19-specific mutations in the 5' flanking region of the G gamma-promoter. The patient homozygous for haplotype No. 19 was a Jordanian, while the others were Kuwaiti Arabs. The latter appear to be fairly homogeneous in terms of the prevalent alpha-thal determinants and beta S-haplotypes, but there is considerable heterogeneity of their beta-thal alleles. This has implications for genetic counseling and prenatal diagnosis programs.

Polymorphic pattern of the (AT)X(T)Y motif at -530 5' to the beta-globin gene in over 40 patients homozygous for various beta-thalassemia mutations

Nucleotide sequence analysis of the 5' beta-globin gene flanking region has been carried out for numerous homozygous beta-thalassemia patients with different mutations and of various ethnic backgrounds. Four different rearrangements were found associated with numerous beta-thalassemia mutations. The (AT)X(T)Y repeat motif at -530 showed polymorphic patterns among these patients as follows: All ten IVS-II-1 (G-->A) chromosomes and the two with the -87 (C-->G) mutation are associated with the (AT)9(T)5 rearrangement, while the 30 IVS-I-6 (T-->C), the 16 codon 39 (C-->T), the six codon 8 (-AA) chromosomes, and 12 chromosomes with different promoter mutations had the (AT)7(T)7 motif. Six chromosomes with the promoter mutation at position -29 (A-->G) had the (AT)8(T)6 motif, while an (AT)8(T)4 motif appears characteristic for two IVS-I-5 (G-->A and G-->T). No direct association between any of the (AT)X(T)Y arrangements and an increased gamma gene expression [G gamma and fetal hemoglobin (Hb F)] levels could be demonstrated, suggesting that variations in the (AT)X(T)Y motif are common polymorphisms.

Spleen in sickle cell anemia: comparative studies of Nigerian and U.S. patients

Anecdotal reports have attributed persistent splenomegaly in African sickle cell anemia (SS) patients to the effects of malaria. However, no comparative studies of patients in malarial and nonmalarial regions have been conducted, and few studies of malaria antibody titers have been reported. In the present study, age- and sex-matched Nigerian patients (n = 310), while it was found only in 8% of U.S. patients (n = 100) from Georgia. There was significant linear correlation between spleen size and Hb levels and with serum immunoglobulins in the Nigerian group. However, serum complement levels (C3 and C4) were not affected by spleen size. In both groups, patients with splenomegaly had fewer circulating pitted red cells than their counterparts without splenomegaly. The mean +/- SE of IgG-specific malaria antibody titer among the Nigerian patients without palpable spleens was 9,386 +/- 2,036; 9,334 +/- 2,980 in those with spleens between 1 and 5 cm, 16,201 +/- 4,502 in those with spleens between 6 and 10 cm, and 22,445 +/- 8,456 in those with spleens above 10 cm. Coexistent alpha-thalassemia did not influence the prevalence of splenomegaly among the Nigerian SS patients. This study provides additional evidence that malaria plays a significant role in the persistence of splenomegaly in African patients.

Hb F in sickle cell anemia

We have reviewed the methodology for an accurate quantitation of Hb F in the blood of patients with sickle cell anemia, values observed in hundreds of patients of different (racial or ethnic) backgrounds and with differences in severity of the disease, and the various factors that affect the level of Hb F. The latter include sex, age, genetic background or chromosomal haplotypes, variations in the sequences of the locus control region(s) 5' to the epsilon-globin gene, and the presence of an alpha chain deficiency or alpha-thalassemia. Finally, a few remarks about agents effective in increasing the in vivo Hb F synthesis are also included.

Level of fetal hemoglobin in children with sickle cell anemia: influence of gender, haplotype and alpha-thalassemia-2 trait

We have evaluated hematological data for numerous blood samples collected from 51 sickle cell anemia (SS) patients during their first 10 years of life. Haplotypes and alpha-globin gene status were determined in all patients. A total of 482 hematological evaluations and 317 fetal hemoglobin (Hb F) determinations are presented. The data show that the Hb F levels are the highest in patients with haplotypes 3/3 and the lowest in those with haplotypes 20/20. This is reflected in differences in total hemoglobin, PCV value, and RBC counts, which are the lowest in the 20/20 group and the highest in the 3/3 group. Female SS patients with haplotypes 19/19 have higher Hb F levels than their male counterparts; the same was observed for the patients with the 19/3 haplotype combination but not for those with the 20/3 haplotype combination. A concomitant alpha-thalassemia-2 heterozygosity had little or no effect on the hemoglobin level. The data confirm that SS children, aged 1-10 years, with a homozygosity for haplotype No. 20 are most severely affected by their disease.

Haplotypes in SS patients from Nigeria; characterization of one atypical beta S haplotype no. 19 (Benin) associated with elevated HB F and high G gamma levels

We have determined the haplotypes of 669 beta S and 109 beta A chromosomes from numerous members of 297 Nigerian families of various ethnic backgrounds. Among the beta S chromosomes, haplotype 19 was detected in 93.2%, haplotype 17 in 3.4%, and haplotype 20 in 0.1%, while 2.4% represented atypical haplotypes. As many as 60.6% of the beta A chromosomes exhibited haplotype 19 mutations, 8.2% had haplotype 3, and 1.8% had haplotype 20. Two siblings with elevated Hb F and G gamma levels were heterozygous for a beta S chromosome with haplotype 19 and a second chromosome with a hybrid haplotype (termed 19 B). In this hybrid chromosome, haplotype 3-like locus control region (LCR) [hypersensitive site-2 (HS-2)] sequences are in juxtaposition to those of the 5' flanking region of the G gamma promoter of a beta S chromosome with haplotype 19. The presence of this hybrid chromosome is associated with high G gamma values in individuals with both sickle cell anemia (SS) and sickle cell trait (AS); it closely resembles another hybrid beta S chromosome, termed 19 A, observed in a previously reported Turkish SS patient who was homozygous for this chromosome and had high Hb F and high G gamma values. In both instances, it is hypothesized that the haplotype 3-like sequences of the LCR HS-2 contain genetic determinants that can combine with factors produced during hematopoietic stress, resulting in increased gamma-globin gene expression.

Beta S haplotypes in various world populations

We have determined the beta S haplotypes in 709 patients with sickle cell anemia, 30 with SC disease, 91 with S-beta-thalassemia, and in 322 Hb S heterozygotes from different countries. The methodology concerned the detection of mutations in the promoter sequences of the G gamma- and A gamma-globin genes through dot blot analysis of amplified DNA with 32P-labeled probes, and an analysis of isolated Hb F by reversed phase high performance liquid chromatography to detect the presence of the A gamma T chain [A gamma 75(E19)Ile----Thr] that is characteristic for haplotype 17 (Cameroon). The results support previously published data obtained with conventional methodology that indicates that the beta S gene arose separately in different locations. The present methodology has the advantage of being relatively inexpensive and fast, allowing the collection of a vast body of data in a short period of time. It also offers the opportunity of identifying unusual beta S haplotypes that may be associated with a milder expression of the disease. The numerous blood samples obtained from many SS patients living in different countries made it possible to compare their hematological data. Such information is included (as average values) for 395 SS patients with haplotype 19/19, for 2 with haplotype 17/17, for 50 with haplotype 20/20, for 2 with haplotype 3/3, and for 37 with haplotype 31/31. Some information on haplotype characteristics of normal beta A chromosomes is also presented.

A new variant, HB Muscat [alpha 2 beta (2)32(B14)Leu----Val] observed in association with HB S in an Arabian family

The silent Hb Muscat with a Leu----Val replacement at position beta 32 was discovered by reversed phase high performance liquid chromatography in two members of an Arabian family from Oman; in one person Hb Muscat occurred with Hb S and in the other with Hb A. Hb Muscat is slightly unstable but its presence has no apparent adverse effect on the health of its carriers. Additional hemoglobin abnormalities observed in this family were a common alpha-thalassemia-2 (-3.7 kb) and Hb S. The beta S haplotypes in the heterozygous carriers and the two sickle cell anemia patients were #19 (Benin) and #20 (Bantu); the latter likely originated from an East African population.

Serum amylase levels in homozygous sickle cell patients

Serum amylase was evaluated in a group of 26 steady-state homozygous sickle cell (SS) patients and 11 age-matched HbAA controls. Half (50%) of the SS patients had values above normal while only two of the control group had slightly elevated values. The SS patients had a mean +/- SD value of 301.46 +/- 119.40 iu/L while the control group had 274.36 +/- 89.70 iu/L. The difference between these two values is statistically significant (P less than .05). Males in both groups had significantly higher mean serum amylase values. The values in the SS group did not show an association with age. Higher levels in SS patients suggest a predisposition to chronic pancreatitis.