Robertsonian translocation 15;21 can present itself clinically in the development of iAMP21-ALL. This specific form of ALL exhibits intrachromosomal amplification of a copy of chromosome 21. It occurs on average 9 years later than the other subtypes of pediatric ALL (which are detected on average between 2-5 years of age). In addition, it is also characterized by a low leukocyte count. The risk of developing iAMP21-ALL is around 2700 times higher compared to the general population.
The presence of ring chromosome 21, is also associated with an increased risk of developing iAMP21-ALL.