Among CCM patients (n = 20 and n = 39, respectively), all were diagnosed with a median CD4 count of <200 (38 [IQR, 25.5–68.5] cells/μL in Kenya and 43 [IQR, 4–74.5] cells/μL in DRC) and 83.3% and 91.6% of these had a CD4 count of <100 cells/μL. This evidence concerns the gene CD4 and cerebral cavernous malformation.