What is one of the variants due to changes in the β-chain gene associated with sickle cell disease?

Sickle cell disease is primarily caused by a specific mutation in the β-globin gene, which results in the formation of Hemoglobin S (HbS). This variant occurs due to a single nucleotide substitution where adenine is replaced by thymine in the DNA sequence of the β-globin gene. As a result, the amino acid glutamic acid is replaced by valine at the sixth position of the β-globin chain. Hemoglobin S leads to the characteristic sickling of red blood cells under low oxygen tension, which is the hallmark of sickle cell disease. This altered shape of the red blood cells can cause various complications such as pain crises and increased risk of infection.

In contrast, Hemoglobin C and Hemoglobin A2 are other variants that differ from Hemoglobin S but are not directly associated with sickle cell disease. Hemoglobin F is fetal hemoglobin, which has a different composition and is prevalent during fetal development but does not cause the sickling characteristic of the disease. Understanding these distinctions is crucial for studying the pathophysiology of sickle cell disease and its genetic basis.