This open-label, parallel group study will evaluate the effect of renal function on the pharmacokinetics of RO4995855 following multiple oral dose administration of RO5024048 and assess the effect of renal impairment on safety and tolerability of RO5024048. Adult males or females with either normal renal function or mild or moderate renal impairment will receive RO5024048 orally for 5 days. Target sample size is <50.