This would provide the molecular explanation of the evidence that A‐T patients (as well as Atm−/− mice) show a reduced number of CD4‐single positive (CD4+) cells (Nissenkorn & Ben‐Zeev, 2015), which, strikingly, exactly phenocopies Gsnor−/− mice lymphopenia (Yang et al, 2010). This evidence concerns the gene CD4 and lymphopenia.