Hemoglobin J Guantanamo [α 2 β 2 128 (H6) Ala→Asp] in association with hemoglobin C and α‐thalassemia in a family from Benin

Hemoglobin J (HbJ), Guantanamo, which had been described but once in the literature, was found in a tamily originating from Benin; this second case was found to be in association with hemoglobin C (HbC) and α‐thalassemia. High‐performance liquid chromatography (HPLC) procedures and microsequencing were used for characterization of the aminoacid substitution. The main hematological disorder, in relation with the instability of Hb J Guantanamo, seems to be a worsening of the rheological properties of the red blood cells (RBC), as demonstrated by ektacytometric studies. Oxygen‐binding properties of the RBC were almost normal, but a slight decrease in cooperativity and lowered Bohr and 2,3‐diphosphoglycerate (DPG) effects were observed for pure stripped Hb J Guantanamo. The expression of the electrophoretic charge difference was partly masked, as is often observed when the structural abnormality is situated in or near a contact area.