When Hb Adana combines with other α-globin deletions, this may yield various forms of phenotypes, ranging from mild anaemia (Table 3) (as in –α3.7 and –α4.2) [39, 40] to a more critical HbH-like condition (− − 20.5 and –α4.2-QT (Q-Thailand) [41]. This evidence concerns the gene HBA2 and anemia.