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

BACKGROUND: In Tunisia, thalassemia and sickle cell disease 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 a series of red blood cell indices and parameters in differentiation of beta-thalassemia trait (ß-TT) from iron deficiency anemia (IDA) and between homozygous sickle cell disease (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 ß-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 Youden's index 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 ß-TT, 125 IDA, 31 SS and 17 ST patients. RESULTS: Srivastava Index, mean corpuscular hemoglobin, red blood cell, Mentzer Index (MI) and mean corpuscular hemoglobin concentration show the highest reliability in discriminating ß-TT from IDA with new cut-offs slightly different from those described in literature. Ehsani Index, mean corpuscular volume, MI, Shine and Lal Index and Sirdah Index are the most powerful in the differentiation between SS and ST. CONCLUSIONS: The effectiveness and the simplicity of calculation of these indices make them acceptable and easy to use for differential diagnosis.

Red cell indices: differentiation between ß-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 ß-thalassemia trait (ß-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 ß-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 Youden's 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 ß-TT, 125 IDA, 31 SS, and 17 ST patients. RESULTS: Srivastava Index (SI) shows the highest reliability in discriminating ß-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 ß-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 ß-TT with atypical HbA2 levels.

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

BACKGROUND: ß-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 ß-Knossos codon27 (G→T) (ßKnossos) 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 ß-globin genes. RESULTS: We noted that heterozygous inheritance of the ßKnossos mutation results in a mild ß-thalassemia phenotype with a low level of HbA2 while homozygous leads to intermediate ß-thalassemia with an atypical high performance liquid chromatogram showing a complete absence of HbA2 and HbF. Compound heterozygosity of the ßKnossos with ß0 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 ßKnossos alleles were found to be associated with a single Mediterranean ß-haplotype I similar to that observed in previous reports from Algeria, Egypt, Cyprus, and Turkey. CONCLUSIONS: The chromosome supporting the ßKnossos 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 ß-thalassemia trait and the other has a normal HbA2 level associated with abnormal red cell indices becomes a necessity to avoid missing thalassemia carriers.