CD4 and Parkinson disease: The study by Di Francesco et al. (2021)4 showed that in iRBD subjects CD4+ T cells exhibit a peculiar molecular signature strongly resembling cells from PD patients, while the study by Pinoli et al. (2024)5 thereafter revealed that STAT1, GATA3 and FOXP3 mRNA levels in CD4+ T cells are promising predictive biomarkers of phenoconversion in iRBD patients.