All of the following statements regarding Sickle Cell Anemia is true, EXCEPT:
Sickle cell anemia is an autosomal recessive disorder, caused by an amino acid substitution of valine for glutamine in the sixth position on the beta-globin chain. Onset of the disease stas during the first year of life especially after 6 months of age, when hemoglobin F levels falls, as a signal is sent to switch from production of gamma globin to beta globin. Hemoglobin S is unstable and polymerizes during hypoxemia and acidosis, leading to sickling of red blood cells. Patients develops jaundice, pigmented gallstones, spleenomegaly, and poorly healing ulcers over the lower tibia. Acute painful episodes can occur due to acute vaso-occlusion by clusters of sickled red cells during infection, dehydration, or hypoxia. Common sites of acute painful episodes include the bones and the chest. Ref: Current Medical Diagnosis and Treatment 2012, Chapter 13 ; Medical Assisting: Administrative and Clinical Competencies By Lucille Keir, 6th Edition, Page 471
Patients require frequent blood transfusions
Patients usually presents before the age of 6 months
There is a positive correlation between HBS and polymerization of HBS
Reccurent infections is the most common cause of death