Haemoglobin J Guantanamo (alpha 2 beta 2 128 (H6) Ala replaced by Asp). A new fast unstable haemoglobin found in a Cuban family.

Haemoglobin J Guantanamo (alpha 2 beta 2 128 (H6) Ala replaced by Asp) was found during a screening from abnormal haemoglobins in three members of a Cuban family, of negro ancestry. The substitution in this variant is located at the alpha 1 beta 1 contact. This explains the slight instability and the mild haemolytic anaemia and morphological abnormalities found in the carriers of this variant. The instability of haemoglobin J Guantanamo indicates that the presence of Asp at the position beta-128 (H6) weakens the alpha 1 beta 1 contact.