Final answer:
Sickle cell anemia is a genetic disorder passed through autosomal recessive inheritance and is not caused by environmental factors like sunlight, parasites, radiation, or chemicals. It is characterized by the production of abnormal hemoglobin, which causes red blood cells to sickle. This condition can trigger serious health issues, especially when individuals have two copies of the sickle cell gene.
Step-by-step explanation:
Sickle Cell Anemia Inheritance and Causes
Sickle cell anemia is an inherited genetic disorder characterized by the production of abnormal hemoglobin S, which can cause red blood cells to assume a sickle shape, especially at low oxygen concentrations. This condition leads to serious health problems due to the obstruction of blood flow in capillaries. Sickle cell anemia is passed from parents to offspring through autosomal recessive inheritance, which means that a child must inherit one copy of the mutant gene from each parent to manifest the disease. Factors such as excessive exposure to sunlight, infections by parasites like Dracunculus medinensis, ovum exposure to radiation before fertilization, or prolonged exposure to chemicals do not cause inherited changes; they are environmental factors that may affect individuals but do not alter the genetic makeup that is passed to offspring.
The condition arose in areas where malaria was common, and heterozygous individuals with one copy of the gene for sickle cell showed some resistance to malaria, suggesting a selective advantage in those regions. Those with two copies of the gene, however, develop the full-blown disease, which is associated with various symptoms and complications. Stressors such as infection or dehydration can trigger sickle cell crises in affected individuals.