Duffy blood group system genotyping in an urban Tunisian population.

BACKGROUND: The Duffy blood group system, besides its relevance in transfusion medicine, is of major interest for population genetics. In fact, the Duffy molecule is the only red cell receptor for Plasmodium vivax, thus the fixation of FY*silent allele in western south-Saharan Africa resulted in the absence of this type of malaria in that area (for a review see Kwiatowski, Am J Hum Genet 77:171-192, 2005). For the Duffy functional role see, for example, Daniels (Vox Sanguinis 93:331-340, 2007). METHODS: Duffy blood group distribution in 115 unrelated Tunisians was determined using the polymerase chain reaction with sequence specific primer (PCR-SSP) method detecting the five allelic versions of the FY gene. The red cell antigenic FY phenotype, for each donor, was deduced through DNA analysis. The blood samples of the positive FY*X alleles were investigated by serological methods, mainly the fixation-elution technique. RESULTS: The following allele frequencies were found (after having excluded FY*X, which had frequency of 0.0174): FY*1 = 0.291 (expressed 0.260; silent 0.031); FY*2 = 0.709 (expressed 0.427; silent 0.282). The most surprising result in this work is the detection of the FY*1 silent allele, usually quite rare, in four samples (1.74%). For FY*2 silent, the predominant allele in Africans, genotyping results showed a prevalence of 29.57%. The FY locus was in Hardy-Weinberg equilibrium in the present sample. CONCLUSION: When compared with European and African data, Tunisian samples demonstrated the presence of the common signs of these two ancestries (FY*2 and FY*X for the first population; and FY*2 silent for the last one). These data confirm the mixed roots of this urban Tunisian population already suggested by numerous studies on other haematological markers.

Prospective randomised comparison of the COBE spectra version 6 and haemonetics MCS(+) cell separators for hematopoietic progenitor cells leucapheresis in patients with multiple myeloma.

A randomised crossover trial of two separators was undertaken to compare the mononuclear cell, CD34(+) cell and CFU-GM yield, in patients (<61 years) with previously untreated symptomatic multiple myeloma. After first-line therapy, all patients received mobilising chemotherapy (cyclophosphamide 4 g/m(2)) and daily G-CSF. The first leucapheresis was performed on the first day the peripheral blood absolute CD34(+) cell count was > 20 cells/microl. All patients underwent 2 leucaphereses on consecutive days. The patients were randomised to undergo either the first or second leucapheresis using the COBE Spectra. The target duration of the procedure on the COBE Spectra was 2 total blood volumes, and for the Haemonetics MCS(+) it was 20 cycles with four recirculations. Between September 2003 and March 2005, 60 patients were entered in the study. COBE Spectra version 6 processed significantly larger volumes of blood than the Haemonetics MCS(+) (8,845 and 5,680 ml, respectively, P < 0.01). The absolute yield of mononuclear cells (2.1 vs. 1.5 x 10(8)/kg, P = 0.04), CFU-GM (11 vs. 3 x 10(4)/kg, P = 0.01) and CD34(+) cells (3 vs. 1.7 x 10(6)/kg, P = 0.02) were all significantly higher with the COBE Spectra version 6, as were the yields per unit volume of blood processed. In conclusion, our study shows that COBE Spectra Version 6 is faster and has a better yield than the Haemonetics MCS(+), in patients with multiple myeloma.

Prevalence of C282Y and H63D mutations in the haemochromatosis (HFE) gene in Tunisian population.

The studies of the HFE mutations: H63D and C282Y in North African populations have revealed the extreme rarity or even the absence of the C282Y mutation. We have examined 1140 chromosomes (570 Tunisian people) for the presence of the two HFE mutations by PCR-RFLP analysis. We have found that the allele frequencies are, respectively, 15.17% (+/-2.1%) for the H63D and 0.09% (+/-0.17%) for the C282Y. These results are consistent with the worldwide spread of the H63D mutation and the north European restriction of the C282Y. This study will be completed by determining whether homozygote trait for H63D and associated risk factors (beta thalassémia) can lead to iron overload in Tunisia.

HLA polymorphism in type 1 diabetes Tunisians.

Several studies of the association between HLA and type 1 diabetes have been carried out revealing differences between ethnic groups. Our study, as part of the studies that should be performed about this association in the rest of the word, aims at elucidating the HLA DRB1, DQB1 polymorphism in Tunisian type 1 diabetes. This study includes 43 unrelated type 1 diabetes patients, and their mean age at onset is less than 15 years. Analysis of the frequency of alleles and haplotypes in these subjects, compared to a reference group (n = 101) led to the following results. 1) The Tunisian insulin-dependent diabetics present similarities as well as differences with other ethnic groups (Caucasians, North Africans). 2) The haplotype DRB1*04 DQ*0302 and DRB1*03 DQB1*0201 is positively associated to type 1 diabetes. 3) The heterozygotic genotype DRB1*04 DQB1*0302 / DRB1*03 DQB1*0201 is strongly associated to type 1 diabetes. 4) The haplotypes DRB1*01501 DQB1*0602 and DRB1*11 DQB1*0301 proved to be protective. In addition, the study of the subtypes DRB1*04 showed that alleles DRB1*0405 predispose to type 1 diabetes, whereas the allele DRB1*0403, which is in linkage disequilibrium with the DQB1*0402 in the Tunisian population, has a protective effect.

[Autologous transfusion program]. / La transfusion autologue programmee.

The term autologous transfusion describes transfusion of any blood component that was donated by intended recipient. A recipient who serves as his or her own donor receives the safest possible transfusion in that the risks of transfusion-transmitted infection and alloimmunization are eliminated. A preoperative autologous transfusion program provides many benefits to the donor-patient the blood donor center and the hospital transfusion service; requires a good communication between the transfusion physician and the collecting facility and needs a rigorous technical organization of the blood bank to ovoid the human errors of testing and labeling. Underutilizaton of autologous blood programs in our country is possibly related to a lack of awareness on the part of all the contributors.

Gene frequencies of human platelet antigens in the Tunisian population.

Gene frequencies for the human platelet antigens HPA-1, -3 and -5 in the Tunisian population were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on 93 volunteer blood donors (78 were tested for HPA-1, 90 for HPA-3 and 93 for HPA-5). This study shows the highest frequencies of the HPA-1b (0.25) and HPA-5b (0.22) yet recorded. These antigens are considered as markers of a high risk of platelet alloimmunisation in other populations, and for this reason particular attention should be paid in the case of pregnancy or blood transfusion in this population. The 9 base pair deletion located in intron 21 of the GPIIb gene associated with HPA-3b determinant is present in this population. No individual showed the polymorphism associated with HPA-1b (T-->G at codon 40 of the GPIIIa).

[HCV antibodies in hemodialyzed patients in Tunisia]. / Anticorps anti-HCV chez les hémodialysés en Tunisie.

The prevalence of seropositivity to Hepatitis C and B virus and HIV infection in Haemodialysis patients was assessed in sera from 235 patients from 6 dialysis units in Tunisia. Anti-HCV antibodies were found in 106 patients (45.10%), the hepatitis B surface antigene was found in 19 patients (8%), and no case of HIV infection was found. Anti-HCV positivity was correlated with duration of dialysis (p < 0.001). There was no correlation between anti-HCV positivity and the number of transfusions.

[Study of class I HLA polymorphism in the Tunisian population]. / Etude du polymorphisme HLA de classe I dans la population tunisienne.

The HLA class I gene polymorphism (HLA-A, -B) was investigated in a population of 102 Tunisians. Allele and haplotype frequencies as well as linkage disequilibrium between HLA-A and HLA-B loci were calculated and compared with other populations. The most frequent alleles were A2 (23%), A30 (12.5%), A3 (10.2%), A1 (8.5%), A23 (7.4%) for the HLA-A locus and B21 (14.3%), B44 (11.4%), B35 (9.6%), B5 (8.5%) for the HLA-B locus. The most frequent haplotype was A3 B21 (2.6%) and a positive linkage disequilibrium was found for the following allelic associations: A11 B35 (X2 = 6.8), A28 B35 (X2 = 5.3), and A30 B35 (X2 = 5). In conclusion, a specific distribution of HLA class I components in terms of antigen and haplotype frequencies characterizes the Tunisian population. This specific pattern may reflect the great ethnical diversity of this community. All these informations may be helpful in the future for HLA and disease association studies.

Red cell alloantibodies in patients with haemoglobinopathies.

The present study was carried out to determine the evidence of alloimmunization against red blood cells in 364 patients transfused in our center over a period of 4 years (1990-1993). Among these patients, 127 were thalassemic and 182 had sickle cell disease (SCD). In 55 control patients, who received blood matched for the ABO, Rhesus and Kell antigen systems from the outset of transfusion, no immunization was detected. However, in the study group, who initially received blood matched only for ABH and Rh D antigens, the frequency of alloimmunization was 7.76% (24/309). Only one antibody was detected in 15 patients (62.5%) and two or more in 9 patients (37.5%). Alloimmunization concerned the Rhesus system in 58.82% of cases and the Kell system in 26.47%, while the frequency of immunization was significantly lower in patients of less than 5 years as compared to those in the age range 5-10 years (p < 0.001).

[ABO system polymorphism in the Tunisian population]. / Polymorphisme du système ABO dans la population tunisienne.

A survey carried out on 18820 Tunisian blood donors enabled us to evaluate the distribution of ABO blood group in Tunisia. The genic frequencies in ABO system were as follows: A(0,192), B(0,122), O(0,686).

[Rhesus system polymorphism in the Tunisian population]. / Polymorphisme du système rhésus dans la population tunisienne.

A survey carried out on 4129 Tunisian blood donors permitted to evaluate the distribution of Rhesus blood group in Tunisia. The haplotypes frequency were as follow, R1: 0,367 r: 0,284 R0: 0,2082 R2: 0,1218 R': 0,00188 r'': 0,0001.

[Epidemiologic study of anti-HCV antibodies in Tunisian blood donors]. / Etude épidémiologique des anticorps anti-HCV chez les donneurs de sang en Tunisie.

A study carried out on 2,006 Tunisian blood donors permitted us to evaluate the prevalence of hepatitis C virus antibodies (anti-HCV) which was 1.09%; frequency of indirect markers of NANBH were as follows: ALAT greater than 2 N (1.24%), anti-HBc (30.35%), 55.5% of HCV (+) donors had anti-HBc (+), 12.5% had rises ALAT and only 33.3% both markers.