In MS patients, low number and impaired function of Treg cells [7] could explain the massive production of IFN\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\gamma$$\end{document}γ and IL-17, during the exacerbation phases of MS. The gene discussed is IL17A; the disease is myeloid sarcoma.