Chaima Abdelhafidh Sahli

Red cell indices: differentiation between β-thalassemia trait and iron deficiency anemia and application to sickle cell disease and sickle cell thalassemia.

BACKGROUND In Tunisia, thalassemia and sickle cell disease (SS) represent the most prevalent monogenic hemoglobin disorders with 2.21% and 1.89% of carriers, respectively. This study aims to evaluate the diagnosis reliability of 12 red blood cell (RBC) indices in differentiation of β-thalassemia trait (β-TT) from iron deficiency anemia (IDA) and between homozygous SS and sickle cell thalassemia (ST). METHODS The study covered 384 patients divided into three groups. The first one is composed of 145 control group, the second consists of 57 β-TT and 52 IDA subjects and the last one with 88 SS and 42 ST patients. We calculated sensitivity, specificity, positive-predictive values, negative-predictive values, percentage of correctly identified patients and Youdens Index (YI) for each indice. We also established new cut-off values by receiver operating characteristic curves for each indice. An evaluation study was performed on another population composed of 106 β-TT, 125 IDA, 31 SS, and 17 ST patients. RESULTS Srivastava Index (SI) shows the highest reliability in discriminating β-TT from IDA at 5.17 as a cut-off and also SS from ST with 7.7 as another threshold. Mentzer Index (MI) and RBC appear also useful in both groups with new cut-offs slightly different from those described in literature for β-TT and IDA. CONCLUSIONS The effectiveness and the simplicity of calculation of these indices make them acceptable and easy to use. They can be relied on for differential diagnosis and even for diagnosis of β-TT with atypical HbA₂ levels.

Fortuitous description of hemoglobin Hope in a high-level Tunisian athlete: molecular diagnosis and origin

In this study we report the fortuitous description of hemoglobin (Hb) Hope in a Tunisian athlete. This Hb is one of hemoglobin variants that show a lower stability and oxygen affinity that is beneficial to tissue oxygen delivery. Hb Hope was isolated by automated high performance liquid chromatography and was unequivocally found to be Hb Hope using DNA-based methods: polymerase chain reaction, denaturing gradient gel electrophoresis, direct DNA sequencing. Restriction haplotype showed that this Hb was supported by the Mediterranean haplotype I. Hb Hope was identified at first in a black African-American family and later in several other black and non black ethnic groups. All these descriptions raise the question of the Hb Hope origin. Recently, Hb Hope was reported in Thai in association with the same Mediterranean haplotype I. This favors that Tunisian and Thai Hb Hope would share a common Mediterranean origin, thus suggesting the possibility of a Mediterranean gene flow. On another hand, the observation of Hb Hope in a high level athlete would suggest a selection pressure of this Hb variant due to higher physical aptitude.

New frameshift CF mutation 3729delAinsTCT in a Tunisian cystic fibrosis patient

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δ0-Thalassemia in cis of βKnossos globin gene: first homozygous description in thalassemia intermedia Libyans and first combination with codon 39 (C→T) in thalassemia intermedia Tunisian patients.

Abstract Background: β-Thalassemia is the most common disease among hemoglobinopathies in North African and Arab populations. In the present study we report the first description of the β-Knossos codon27 (G→T) (βKnossos) allele in cis with the δ059 (-A) mutation in thalassemia intermedia patients in Tunisia and Libya. Methods: This identification was carried out by sequencing analysis of the whole coding regions of the δ- and β-globin genes. Results: We noted that heterozygous inheritance of the βKnossos mutation results in a mild β-thalassemia phenotype with a low level of HbA2 while homozygous leads to intermediate β-thalassemia with an atypical high performance liquid chromatogram showing a complete absence of HbA2 and HbF. Compound heterozygosity of the βKnossos with β0 codon39 (C→T) is identified in a Tunisian proband for the first time and gives rise to a mild phenotype. In both families, the δ0 codon59 (-A) and the βKnossos alleles were found to be associated with a single Mediterranean β-haplotype I similar to that observed in previous reports from Algeria, Egypt, Cyprus, and Turkey. Conclusions: The chromosome supporting the βKnossos and the δ0 codon59 (-A) alleles seems to be of a single Mediterranean origin. Premarital screening studies in families in which only one of the parents has typical aspects of β-thalassemia trait and the other has a normal HbA2 level associated with abnormal red cell indices becomes a necessity to avoid missing thalassemia carriers.

Determination of glucose-6-phosphate dehydrogenase cut-off values in a Tunisian population.

Abstract Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the commonest enzymopathy worldwide. The incidence depends essentially on the methods used for the assessment. In this respect, we attempted in this study to set cut-off values of G6PD activity to discriminate among normal, heterozygous, and deficient individuals using the World Health Organization (WHO) classification and the receiver operating characteristics (ROC) curve analysis. Methods: Blood samples from 250 female and 302 male subjects were enrolled in this study. The G6PD activity was determined using a quantitative assay. The common G6PD mutations in Tunisia were determined using the amplification refractory mutation system (ARMS-PCR) method. The ROC curve was used to choice the best cut-off. Results: Normal G6PD values were 7.69±2.37, 7.86±2.39, and 7.51±2.35 U/g Hb for the entire, male, and female groups, respectively. Cut-off values for the total, male, and female were determined using the WHO classification and ROC curves analysis. In the male population, both cut-offs established using ROC curve analysis (4.00 U/g Hb) and the 60% level (3.82 U/g Hb), respectively are sensitive and specific resulting in a good efficiency of discrimination between deficient and normal males. For the female group the ROC cut-off (5.84 U/g Hb) seems better than the 60% level cut-off (3.88 U/g Hb) to discriminate between normal and heterozygote or homozygote women with higher Youden Index. Conclusions: The establishment of the normal values for a population is important for a better evaluation of the assay result. The ROC curve analysis is an alternative method to determine the status of patients since it correlates DNA analysis and G6PD activity.

Setup of a Protocol of Molecular Diagnosis of β‐Thalassemia Mutations in Tunisia using Denaturing High‐Performance Liquid Chromatography (DHPLC)

β‐Thalassemia is one of the most prevalent worldwide autosomal recessive disorders. It presents a great molecular heterogeneity resulting from more than 200 causative mutations in the β‐globin gene. In Tunisia, β‐thalassemia represents the most prevalent monogenic hemoglobin disorder with 2.21% of carriers. Efficient and reliable mutation‐screening methods are essential in order to establish appropriate prevention programs for at risk couples. The aim of the present study is to develop an efficient method based on the denaturing high‐performance liquid chromatography (DHPLC) in which the whole β‐globin gene (HBB) is screened for mutations covering about 90% of the spectrum.

Association of MP6d9 Polymorphism with Clinical Variability in Cystic Fibrosis Patients

BACKGROUND In this work, we are interested to study for the first time the extragenic polymorphic marker MP6d9 in cystic fibrosis and healthy cohort in Tunisia to establish the contribution of MP6d9 polymorphism in the phenotypic variability of CF patients. METHODS Our study enrolled 112 CF patients and 100 healthy controls. The analysis of the polymorphic marker MP6d9 was performed using the PCR-RFLP technique. RESULTS Statistical difference was found in the genotype and allelic distribution between CF patients and control groups. We found that the 2/2 genotype was higher in CF patients than in controls (58.9% vs 23%). We noted that the 2/2 genotype is associated with severe clinical manifestations. CONCLUSION Based on the above data, it seems that this genotype has led to the deterioration of our patients clinical manifestation. This study enabled us to understanding the involvement of the MP6d9 marker in the CF clinical expression in the Tunisian population.