The expression of JAK/STAT pathway genes is upregulated in ENKTL, and mutations in JAK3, STAT3, and STAT5B lead to constitutive activation of the JAK/STAT pathway, which occurs on the transcription factor jak3 in about 35% of cases, resulting in severe immunodeficiency characterized by a lack of T and NK cells [76, 77]. Here, JAK3 is linked to Immunodeficiency.