Hemoglobin Athens-Georgia [alpha 2 beta 2 40(C6)Arg----Lys] in association with beta 0-thalassemia in Tunisia.

We describe an Hb Athens-Georgia (Hb A-Ga)/beta 0-thalassemia compound heterozygosity, found in a Tunisian patient. Oxygen binding studies of red cell suspensions of this patient, containing approximately 95% Hb A-Ga, revealed an almost normal oxygen affinity. Nevertheless, dilute solutions of Hb A-Ga showed an increased overall oxygen affinity and decreased heme-heme interaction. This could be explained by a tetrameric hemoglobin with normal oxygen binding properties but with increased dissociation into monomers or dimers, as a consequence of a structural abnormality within the alpha 1 beta 2 interface. Such an interpretation would explain the increased oxygen affinity reported in previous studies performed on heterozygous Hb A/Hb A-Ga patients.

Iron stocks and risk of anemia in twins.

This study aims to compare the risk of anemia by iron deficiency in mothers and infants of twin and single pregnancy. It concerned 33 couples of twins and 31 control, all 97 being term newborns. At birth, ferritinemia is significantly lower in twins, and reticulocytes count is significantly higher; their mothers have a significantly lower hemoglobin level and higher reticulocytes percentage and count. At 3 and 6 months, hemoglobin level and mean corpuscular hemoglobin are significantly lower in twins, as at 6 months ferritinemia is significantly lower in twins. Iron stocks constituted in utero are significantly lower in twin pregnancy, and this study support the early preventive iron treatment in twins.

Incidence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Tunisian populations.

Screening for glucose-6-phosphate dehydrogenase (G6PD) deficiency was performed on male students originating from several towns in Tunisia. Three hundred and twenty-five assays were made, allowing calculation of the mean value and standard deviation of G6PD (6.32 +/- 0.72 U/g Hb), the incidence of the deficiency (1.84%) and its geographic distribution in Tunisia. G6PD electrophoresis in 54 subjects showed marked predominance of the B+ type (96.2%) compared with the A+ type (1.96%). Three deficient subjects displayed an electrophotetic mobility identical to that of the A+ type of G6PD.

Spectrin Tunis (alpha I/78): a new alpha I variant that causes asymptomatic hereditary elliptocytosis in the heterozygous state.

Spectrin Tunis (alpha 1/78) was found in the heterozygous state in a young white North-African man and his mother. Both of them presented with mild elliptocytosis. Using one-dimensional electrophoresis, a sharp 78 kd fragment was present with a reciprocal decrease of the alpha I 80 kd domain. Kinetic analysis unambiguously confirmed that the 78 kd fragment developed at the expense of the alpha I 80 domain. The alpha I 74 kd peptide was not flanked with a peptide lacking a 2 kd fragment. From this fact, it could be inferred that the site for additional proteolysis is located upstream from arginyl residue 39 and, more precisely, should lie 10 to 20 amino-acid residues (-2 kd) from the alpha-chain N-terminus. The percentage of spectrin dimers in 4 degrees C extracts was high (over 40%), contrasting with the absence of clinical symptoms related to elliptocytosis. This is the first mutation responsible for elliptocytosis found in Tunisia.

Hb Tunis [alpha 2 beta 2 124 (H2)Pro----Ser], a new beta chain variant identified by HPLC.

During a routine hematological investigation of a child from Tunis, a silent hemoglobin variant was discovered by isoelectric-focusing. This variant was not detectable by conventional electrophoretic methods, had normal stability, expression, and oxygen affinity, and did not produce any clinical symptoms. This new variant beta 124(H2)Pro----Ser was named Hb Tunis.