Biphenotypic acute leukaemia (BAL) is a mixture of both types of acute leukaemias, acute myeloid leukaemia (Aml) and acute lymphoblastic leukaemia (ALL). BAL is an uncommon type of leukaemia. It is estimated that around 5% of people with acute leukaemia have biphenotypic leukaemia. BAL can affect people of any age but it’s more common in adults than in children.

This group of leukemias are reported to have structural abnormalities including a high incidence of the Philadelphia chromosome, chromosome rearrangements and other abnormalities.