How does the change in the 17th nucleotide affect the shape of red blood cell of a person with sickle cell disease?

In sickle cell disease, a mutation occurs at the 17th nucleotide of the hemoglobin gene, where adenine (A) is replaced by thymine (T). This single nucleotide change results in the substitution of glutamic acid with valine in the hemoglobin protein. Consequently, under low oxygen conditions, the altered hemoglobin (HbS) tends to polymerize, causing red blood cells to assume a rigid, sickle shape instead of their normal disc shape. This abnormal shape leads to blockages in blood flow and reduced oxygen delivery throughout the body.