Which of the following is NOT a cause of sideroblastic anemia?

Sideroblastic anemia is characterized by the presence of sideroblasts—abnormal red blood cell precursors that contain iron granules in the mitochondria due to a failure in heme synthesis. Common causes of sideroblastic anemia include exposure to certain toxins, deficiencies of essential minerals, and certain medications.

Lead exposure is a well-known cause of sideroblastic anemia, as lead interferes with heme synthesis and can lead to the accumulation of iron in mitochondria. Copper deficiency also contributes to this type of anemia, as copper is critical for iron metabolism and the proper function of enzymes involved in heme synthesis. Isoniazid, an antitubercular medication, has a side effect profile that can include pyridoxine (vitamin B6) deficiency, which can subsequently lead to problems with heme synthesis and thus contribute to sideroblastic anemia.

Vitamin C deficiency, while can affect iron metabolism, is not directly linked to the development of sideroblastic anemia. It does not interrupt the process of heme synthesis in the same way as the other listed causes. As a result, vitamin C deficiency does not lead to the characteristic formation of sideroblasts seen in sideroblastic anemia, making it the correct answer in