Patients have an increased susceptibility to cutaneous beta HPV infections (most commonly HPV-5 and HPV-8) but not to other infections. The lesions present as flat warts or hypo/hyperpigmented macules which respond poorly to conventional therapies. The exact mechanism for HPV susceptibility is not known. Non-melanoma skin cancers associated with HPV-5 occur in over one-third of patients after the second decade of life. EV is caused by homozygous mutations in EVER1 and EVER2.