Individuals with TEC have a median age of presentation of 18–26 months; however, the disorder may occur in infants younger than 6 months and in children as old as age 10 years.

Because of the gradual onset of the anemia, children are often healthier than expected from their low hemoglobin levels.

[citation needed] The cause of TEC is unknown, but it thought to be triggered by a viral infection.

This is in contrast to transient aplastic crisis, seen in patients with hemoglobinopathies such as sickle cell disease, which is usually caused by parvovirus infection.

[1][2] Children typically present with a moderate normocytic anemia (usual range: hemoglobin 5-8 g/dL) and reticulocytopenia.