IL1A and neurodegenerative disease: The “hematopoietic stem cell differentiation” pathway, associated with the PRS for ALS in CD4+CD45RO- T cells, includes pro-inflammatory interleukin genes IL1A, IL1B, and IL6, and the CXCR4 chemokine receptor that may spur T cell migration into CNS tissue, especially during neurodegenerative disease (3).