Molecular identification of Gd A- and Gd B- G6PD deficient variants by ARMS-PCR in a Tunisian population.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy. More than 200 mutations in the G6PD gene have been described. In Tunisia, the A-African and the B-Mediterranean mutations predominate the mutational spectrum. The purpose of this study was to apply the amplification refractory mutation system (ARMS-PCR) to the identification of Gd A+, Gd A- and Gd B- variants in a cohort of deficient individuals and to establish a phenotype/genotype association. 90 subjects were screened for enzymatic deficiency by spectrophotometric assay. The molecular analyses were performed in a group of 50 unrelated patients. Of the 54 altered chromosomes examined, 60% had the Gd A- mutation, 18% showed the Gd B- mutation and in 20% of cases, no mutations have been identified. The ARMS-PCR showed complete concordance with the endonuclease cleavage reference method and agreed perfectly with previous Tunisian studies where Gd A- and Gd B- were the most encountered. Also, similarities in spectrum mutations with North African and Mediterranean countries suggest gene migration from Africa to Europe through Spain. In conclusion, ARMS has been introduced in this study for common G6PD alleles identification in Tunisia. It gives some advantages compared to the traditional endonuclease digestion method since it is more convenient and timesaving and also offers the possibility to be applied in mass screening surveys.

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.