In addition, high level expression of signal transducer and activator of transcription 2 (STAT2) and signal transducer and activator of transcription 4 (STAT4) has been observed in MDV infected macrophages derived from MD susceptible chickens (line 7) compared to resistant chickens (line 6), suggesting dysregulation or overactivation of this pathway may correlate with disease progression (Chakraborty et al., 2019). This evidence concerns the gene STAT4 and Menkes disease.