In mid-2013, the World Health Organisation (WHO) released antiretroviral treatment (ART) guidelines, raising the initiation CD4 threshold to 500 cells/μl for adults (and regardless of CD4 threshold for pregnancy and during breastfeeding, for WHO stages 3 and 4, for discordant couples, and for people with chronic hepatitis B), further simplifying treatment choices and recommending continuing lifelong ART after birth for pregnant women (so-called option B-plus) [1]. The gene discussed is CD4; the disease is chronic hepatitis B virus infection.