Final answer:
The most common forms of hereditary sideroblastic anemia are due to a defective X-linked recessive gene (option A). This genetic mutation is located on the X chromosome. Other anemias like sickle cell anemia and thalassemias follow an autosomal recessive pattern of inheritance.
Step-by-step explanation:
Heredity of Sideroblastic Anemia
The most common forms of hereditary sideroblastic anemia are due to a defective X-linked recessive gene. Sideroblastic anemia is a condition characterized by the presence of ringed sideroblasts in the bone marrow, and a defect in the heme synthesis pathway. This condition causes the red blood cells to become inefficient in delivering oxygen to the body's tissues, leading to symptoms of anemia.
X-linked recessive inheritance means that the genetic mutation causing the condition is located on the X chromosome. Since males (XY) have only one X chromosome, if they inherit the defective gene, they will express the disease. Females (XX) can be carriers of the mutated gene without expressing the disease, since they have a second, potentially normal X chromosome to compensate.
Other forms of anemia, such as sickle cell anemia and thalassemias like beta-thalassemia and alpha-thalassemia, are inherited via autosomal recessive patterns. It is important to note that these conditions are different from hereditary sideroblastic anemia, both in the type of genetic mutation and mode of inheritance.