Final answer:
Carriers of the sickle cell trait have a single mutated allele and usually do not exhibit symptoms unless under extreme stress, and have a protective advantage against malaria in endemic areas. Individuals homozygous for the sickle cell mutation suffer from severe health issues due to the misshapen red blood cells. The sickle cell gene remains common in certain populations due to its protective benefit against malaria.
Step-by-step explanation:
Facts about a patient who carries the sickle cell trait include that these individuals have one mutated and one normal allele for hemoglobin production. Carriers often do not show symptoms of sickle cell anemia unless under extreme conditions such as severe dehydration or low oxygen levels. In areas where malaria is prevalent, such as parts of Africa, carriers of the sickle cell trait have a selective advantage because the trait provides some protection against malaria. Conversely, individuals who are homozygous recessive (ss) express full-blown sickle cell anemia, where all their red blood cells are crescent-shaped, leading to serious health problems. The presence of individuals homozygous for the sickle cell mutation does little to benefit from this anti-malarial effect. However, because of the protection against malaria in heterozygotes, the sickle cell gene remains relatively common, particularly among individuals of African descent, despite the severe health implications for those with two copies of the gene.