Carriers of the sickle cell allele
◦ often do not display symptoms until after they have passed the gene on to their children.
◦ can be treated during infancy if placed on a diet that is low in phenylalanine.
◦ are more resistant to malaria than are individuals with two alleles for normal red blood cells.
◦ develop sickle-shaped red blood cells that cause degeneration of the nervous systems.