Most often the etiology is unknown; however, a few etiological factors are known.
- For identical twins, the risk for developing leukemia for the other twin is significantly higher if one of them develops the disease.
- High doses of radiation in utero.
- Certain hereditary diseases/syndromes are more susceptible to leukemia. Examples are: Down's syndrome, Fanconi's anemia, and ataxia telangiectasia.
- Of environmental factors, there is discussion of electromagnetic fields (power lines) and neonatal exposure of pesticides.
- There is evidence for a two level mutation model in the immune system provoked by viral and/or bacterial infections. This would explain the peak between 2 and 5 years.