Activating mutations in JAK1 (SH2-, pseudokinase -and kinase- domains) have been reported in approximately 5-20% of cases of T-Cell Acute Lymphoblastic Leukemia, in "Ph-like ALL" and in less than 5% of Acute Myeloid Leukemia. Some, but not all, of these mutations have been shown to be inhibitable by ATP-competitive JAK inhibitors or Type I interferon.

This gene is a known cancer gene.

This gene is a known cancer gene.