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.

Inclusion Criteria:

• male or female adults, 18-75 years of age
• normal, or mildly or moderately impaired renal function (creatinine clearance >/= 30 mL/min)
• BMI 18-40 kg/m2
• stable renal function
• agree to abstain from alcohol consumption during study drug adminsitration and limit consumption up to the end of the study
• agree to abstain from coffein consumption throughout study

Exclusion Criteria:

• positive urine or blood test for drugs of abuse not under a physician's prescription
• positive for HIV or HCV, or HBV with clinical symptoms or history of hepatitis
• uncontrolled hypertension
• renal transplant, dialysis patient, nephritic syndrome
• clinically significant cardiovascular, central nervous system, gastrointestinal or liver disease or disorder