The largest cohort study of patients with ICL recently showed that HPV was the most common opportunistic infection, and the risk of opportunistic infection within ICL was directly related to CD4 count.6 Similarly, a study using metagenomic sequencing demonstrated that patients with ICL carry higher readings of HPV in the skin when compared with healthy controls, suggesting that the condition has a differential effect on the skin microbiome.7 This evidence concerns the gene CD4 and idiopathic CD4 lymphocytopenia.