Hb lulu island (α₂β₂107[G9]Gly→Asp)-β°-thalassemia (codon 15; TGG → TAG), a form of thalassemia intermedia

Hb Lulu Island [β107(G9)Gly → Asp] was discovered in an East Indian female who carried a common β°-thalassemia allele, i.e., codon 15, TGG → TAG (is a stop codon) in trans. Both abnormalities were detected through sequencing of the amplified β-globin genes and were confirmed by hybridization with ³²P-labeled probes. Hb Lulu Island is mildly unstable with a borderline decrease in oxygen affinity; its instability is less severe than that of Hb Burke or β107(G9)Gly → Arg. The compound heterozygosity expresses as a thalassemia intermedia with moderate anemia, a variable need for blood transfusions, Heinz body formation, and a red cell morphology which is typical for such a condition. The level of HbA₂ was greatly increased (6.5–7.0%) as was the δ chain level (12% of total non-α) probably because of the instability of Hb Lulu Island and the decreased ability of the β^x chain to form dimers with the normal α chain.