Search

Prevention of sickle cell anemia, a severe and painful disease, relies on carrier detection and information, and on prenatal diagnosis with the possibility of medical abortion. Here we report the first results of a medical and welfare program launched in Paris 20 months ago and dedicated to sickle cell carrier screening and information.

Red blood cells (RBCs) transfusion is a common practice in the treatment or for the prevention of complications of patients with sickle-cell disease. In surgery, pre-operative transfusions are frequently given to prevent peri-operative complications. There is no consensus however on the best regimen of transfusion for this purpose. The transfusion techniques are muliple. In addition, pre-operative transfusion therapy is reported to be largely responsible for an increased morbidity and mortality in patients with sickle cell anemia undergoing surgery. During the period 1990-2000, 16 patients (4 men and 12 women) with a mean age of 37 years and various major sickle cell hemoglobinopathies underwent 32 total hip arthroplasty for femoral head necrosis. Nine patients with sickle-cell trait were included as control group. Twelve of them had haemoglobin SS (HbSS), 2/16 had HbSC, 2/16 had HbS/betathalassemia. Operative transfusion were given in only 12/32 procedures, 4 were performed pre-operatively and 8 intra-operatively. Simple transfusion (mean: 2.5 packed red cells) were administered in all the procedures. The main complications observed in our patients were anemia by hemolysis and haemorrhagic shock, vaso-occlusive crisis and chest syndrome. Anemia requiring transfusions was significatively related to the procedures with pre-operative transfusion. In the light of our result, we would like to propose transfusional protocol--if needed--only intra-operatively.

Sickle cell anemia is a monogenic hereditary disease characterized by a mutation in the beta globin gene. Five major haplotypes associated with the beta S mutation have been defined: Benin, Bantu, Senegalian, Camerounian, and Arabo-Indian. Previous studies in northern Tunisia showed that sickle cell anemia was of Benin origin in this region. Patients from the south of Tunisia, mainly from the Kebili region, were not previously concerned. In this study, we have determined the beta S haplotype and evaluated phenotypical expression of the disease in 14 patients from this latter region. The use of four restriction endonucleases having polymorphic sites in the beta globin gene showed that all patients had the Benin haplotype, confirming the Benin origin of sickle cell anemia in Tunisia. This haplotype is associated with an heterogeneous expression of fetal hemoglobin (HbF) with extremes varying from 2.4 to 16.3% and a mean expression rate of 8.16%, which is in accordance with literature data. In spite of the haplotype homogeneity in our patients, clinical heterogeneity was noted. A unique case of alpha-thalassemia could not explain this heterogeneity. In contrast, we found a certain correlation between fetal hemoglobin expression and clinical severity.

The sickle cell trait (SCT) is a genetic abnormality of the red blood cell which mainly affects people of African descent. It is due to the mutation of only one parental gene (one glutamic acid of the chain beta of the globin is substituted by one valin). The prevalence of SCT in the black US population is within the range of 8-9%. It is increasing in Europe and in Africa where it may reach up to 40% in some regions. The rate of prevalence of SCT in athletic populations was found to be similar to that of the general sedentary population in west African countries. SCT is usually asymptomatic. However, SCT has been associated with a higher risk of sudden death during exercise. In fact, the substitution of one amino-acid modifies the properties of haemoglobin and produces physiological disorders such as sickling, less solubility of the deoxidized form and the reduction of affinity for oxygen. The sickling phenomenon (formation of sickle cells) mainly occurs in some conditions related to the practise of sport (intense and/or prolonged exercise, exercise in hypoxic conditions, exercise in heat conditions). These sickled red blood cells reduce the speed of capillary flow or obstruct the blood vessels which, because of the lack of oxygen, become altered. The physical ability of sickle cell trait carriers (HbAS) who practise sport should be different from the physical ability of subjects with normal haemoglobin (HbAA) because of: 1) potential risks due to their haemoglobinopathy and 2) the eventual modification of their performance ability. These two aspects have caused controversies among many researchers particularly in line with their investigation methods. Nevertheless, the following results seem to be established: 1) the ability to perform sprint exercises is not altered in the HbAS subjects. Their performances in these events are similar to those of HbAA subjects; 2) The ability of HbAS subjects to perform intense and prolonged exercise is decreased. Our former results have shown that prolonged aerobic efforts in hypobaric hypoxic conditions may be associated with a deleterious effect on the performance of HbAS subjects. The damaging consequences on their performance in these conditions could be due to tissue oxygen delivery limitations.

Sickle hemoglobinopathies are frequent in black population. Double heterozygous SC gives less general symptoms but ocular complications are very common. Fluorescein angiography of 20 cases are reported. All the patients had hemoglobin electrophoresis showing double heterozygous SC. Clinical investigations included fundus examination and fluorescein angiography. Laser treatment or cryotherapy were realised regarding lesions features. Vascular retinal complications were found in 75% of cases, including vitreous hemorrhage (10% of cases). There was no correlation between fundus examination and fluorescein angiography. Fluorescein angiography is useful for early diagnosis and allows preventive laser treatment.

A study on the incidence and gravity of malaria among children suffering of sickle cell anemia was carried out in the pediatric hospital of Bamako-Mali. On the 236 cases of fever studied, 54.2% were malaria infected and 21.2% were carriers of the sicklemic trait. There was a significant difference between malaria affecting AA children and HbS children, specially concerning parasites load.

The present study report 7 cases of sickle homozygous disease which have been analysed using markers of the oxidative-stress, 26 african male subjects were studied: 7 Hb SS subjects (age: m = 20) and 19 control subjects (Hb AA, age: m = 40). Plasma concentrations of F-MDA, T-MDA, TBARS, alpha tocopherol, retinol and beta carotene were measured. Plasma MDA and TBARS mean levels increased in sickle homozygous patients more than in controls. However, only TBARS mean concentrations were significantly increased between patients and controls: TBARS: 4.14 +/- 1.49 nMol/ml for Hb SS versus 2.10 +/- 1.21 nMol/ml for Hb AA (P less than 0.005). Vitamin A and vitamin E concentrations were significantly lower in Hb SS than in Hb AA. Beta carotene was significantly increased in patients vs controls. The significant increase of TBARS explains the great importance of the oxidative damage, whereas the significant decrease of vitamins A and E, may contribute, at least for a part, to maintain the autoxidation process or reveals its intensity in these patients.

Hemoglobin electrophoresis realised as a routine screening test on 1 500 gabonese individuals revealed the existence of a sickle cell abnormality n 24.40% cases (22.27% were AS heterozygotous and 2.1% were SS homozygotous). Bapounov and Fang ethnies appeared to be the most involved. The importance of such disturbance (I gabonese individual out of 4 is concerned) could justify the creation of Prenatal Counseling Centers mainly dealing with this genetic problem.

From 1978 to 1979, 5 surveys, among schoolchildren, were carried out during the rainy season in the neighbourhood of Brazzaville (R.P. Congo): 3 in PK 45 village (northern part of the capital), 2 in Djoumouna village (southern part), and 1 in "Talangai" (a suburb of the capital). 868 exams (plasmodic and splenic index fitted with hemoglobin composition [Hb AA or Hb AS]) were done. It appeared that 19,6% of schoolchildren examined were heterozygous sicklers (AS). This percentage confirmed the previous results from other authors in different countries of Central Africa. On the other hand, in spite of an intense transmission, both plasmodic and splenic index were, on the average, relatively low (24,5 and 24,8% respectively). Plasmodium falciparum was largely predominant (95,3% of infections) but P. ovale and P. malariae were also found (1,9% for each species). From our study no obvious "protecting effect" can be attributed to sickle cell trait because plasmodic index of children AA and AS were similar (23,8 and 27,6% respectively). A slight decrease of splenic index was noticed in AS in regard to AA (19,4 and 26.1% respectively). It is difficult to consider this no significative regression as a definitive proof of a premunition stronger in AS than in AA. Effectively some splenic infarctus are well known to be a regular physiopathological process occurring in homozygous SS but often in heterozygous AS too. In such highly endemic and stable malaria area the problem of a suitable antimalaria strategy remains to be solved.

We report the results of a systematic survey carried on 8.961 healthy Guadeloupean blood donors, where we looked for hemoglobinopathies. The results are expressed in regard of the race and site of living (urban or rural) of the subjects. Of these 8.961 subjects, aged 18 to 60, 7.75% were sickle cell trait carriers, 2.36% were heterozygous for Hb C and 0,2% had a significant elevation of Hb F. Were also report some less frequent phenotypes : three Hb AD, five Hb SC, one Hb CC, two Hb SF, one Hb CF and one case of isolated Hb, A2 elevation. Two rare hemoglobinopathies are reported: a case of Hb Korle Bu associated with Hb S an a case of Hb N-Baltimore. Our datas regarding race and sex of Hb S and Hb C carriers are evaluated. These results are compared to previous studies carried on healthy blood donors in Guadeloups. Problems related to the detection of hemoglobin abnormalities in a blood transfusion center are reviewed.

One hundred and twenty-three cases of sickle-cell trait (122 negro immigrants) are studied in a department of internal medicine. The frequencies of G6PD deficiency, anemia, splenomegaly and tuberculosis are neighbouring at the negro without hemoglobinopathy. The relationship between the sickle-cell trait and the reason of admission of the final diagnosis il likely in 2,4 % of the cases, doubtfully in 15,4 %, null in the other cases. The occasional (hemolytic, thrombotic, painful, visceral, osseous) manifestations of the sickle-cell trait (apart from the constant hyposthenuria) and their mechanism are summarized and discussed.

The relationship between sickle cell trait and falciparum malaria was studied in the village of Djoumouna, twenty kilometers south west of Brazzaville. Malaria is characterized by a stable high intensity of transmission on the average one infective mosquito bite by night and by child contrasting with a relatively low malarial infection rate. The prevalence of carriers of an S gene (AS) does not change with age: 22.2% for children under 5 years, 22.1% for childrern between 5 and 15 years, and 22.9% in adults. Malarial infection rates are 32% in homozygous AA children under five years and 38% in AS children, an insignificant difference. Our data for this region of the Congo fail to confirm the hypothesis that the AS genotype protects the carrier against Plasmodium falciparum infection.