These results provide evidence that major changes in expression levels of the PTP family members occur in MS WML. Among the most modulated (P<0.05) PTP genes were Ptpn18/BDP-1 (WML vs CWM/NAWM +14/+15 fold), Ptprq/PTP-GMC1 (−160/−243 fold), Ptpn22/LypPEP (−37/−78 fold), Dusp9/MKP-4 (−26/−30 fold), Ptprr/PTP-SL (−14/−9 fold), Dusp15/VHY (−8/−13 fold) and Ptpn5/STEP (−8/−5 fold). This evidence concerns the gene PTPN18 and myeloid sarcoma.