HOXA9 expression increases with age in human haemopoietic cells.

HOXA9 is a transcription factor with a central role in both haemopoiesis and leukaemia, and has been extensively studied over the past decade. Most notably, high levels of HOXA9 expression in haemopoietic cells is a characteristic feature of acute myeloid leukaemia (AML), and indeed may be sufficient in its own right to cause this disease. Here, we show that HOXA9 expression changes dramatically with age, whereby a uniformly low level of expression during early adulthood is replaced by a frequently very high expression in adults over sixty.