The use of eGFRcys is particularly relevant to those with eGFRcr <75 mL/min/1.73 m2 who have stable kidney function and no proteinuria; in this group, both a switch in antiretroviral therapy and comorbidity-induced anxiety may be avoided if kidney function is more accurately assessed with cystatin C.21 The gene discussed is CST3; the disease is Anxiety.