A total of 22 HBB gene thalassemia variants were identified: 10 null variants leading to complete impairment of β-globin synthesis (β0); 4 with severe reduction in β-globin synthesis (β+); 5 with mild (β++); and 3 variants with very mild (so-called silent) reduction in β-chain synthesis (βsil). The gene discussed is HBB; the disease is thalassemia.