What is a common cause of macrocytic anemia in children?

The common causes of macrocytic anemia in children primarily include vitamin B12 deficiency and folic acid deficiency. Both of these conditions lead to impaired DNA synthesis, resulting in the production of larger red blood cells, which is characteristic of macrocytic anemia.

Vitamin B12 deficiency can occur in children due to dietary insufficiency, particularly in strict vegetarians, or due to malabsorption syndromes such as pernicious anemia. Folic acid deficiency is often related to inadequate dietary intake or can occur in conditions that increase the metabolic demand for folate, such as growth spurts or certain chronic illnesses.

While iron deficiency anemia is the most prevalent type of anemia in children, it typically presents with microcytic anemia, characterized by smaller than normal red blood cells due to a lack of hemoglobin. Down syndrome is a genetic condition that may be associated with several hematological issues but is not recognized as a common direct cause of macrocytic anemia.

The confusion in the answer choice may stem from a misunderstanding of the conditions associated with macrocytic anemia; however, B12 and folic acid deficiencies are the correct associations here.