A Study to Investigate the Effect of Hepatic Impairment on the Pharmacokinetics and Safety and Tolerability of a Single Oral Dose of Risdiplam Compared to Matched Healthy Participants With Normal Hepatic Function

Inclusion Criteria: All Participants: * BMI between 18.0 and 36.0 kilograms per square metre (kg/m2), inclusive, and body weight \> / = 50 kg * Females must not be pregnant or lactating and must be of non-childbearing potential * Male participants (whether surgically sterilized or not) with female partners of childbearing potential must use methods of contraception from Screening until 4 months after their dose of the study drug as detailed in the protocol * Male participants must not donate sperm from Check-in (Day -1) until 4 months after their dose of the study drug Participants with Normal Hepatic Function Only: * Matched to participants with mild or moderate hepatic function in sex, age, BMI, and smoking status * In good health, as determined by no clinically significant findings from medical history, physical examination, 12-lead ECG, vital sign measurements, and clinical laboratory evaluations Participants with Hepatic Impairment Only: * Documented chronic stable liver disease * Currently on a stable medication regimen, defined as not starting new drug(s) or changing drug dose(s) within 3 months of administration of study drug * Anemia secondary to hepatic disease will be acceptable, if hemoglobin \>/= 9 gram per decilitre (g/dL). Participants must have a platelet count \</= 35 000 platelets Exclusion Criteria: All Participants * Significant history or clinical manifestation of any metabolic, allergic, dermatological, renal, hematological, pulmonary, cardiovascular, gastrointestinal, neurological, respiratory, endocrine, or psychiatric disorder * History of significant hypersensitivity, intolerance, or allergy to any drug compound, constituents or excipients of the study drug, food, or other substance * History of stomach or intestinal surgery or resection that would potentially alter absorption and/or excretion of orally administered * Ventricular dysfunction or history of risk factors for Torsades de Pointes * Evidence of hepatorenal syndrome and estimated creatinine clearance range \< 60 millilitre per minute (mL/min) or abnormal sodium and potassium levels * Clinically significant physical examination abnormality * History of diabetes mellitus * Use or intend to use any medications/products known to alter drug absorption, metabolism, or elimination processes, including St. John's Wort * Positive human immunodeficiency virus (HIV) test * Participation in a clinical study involving administration of an investigational drug prior to dosing * Smoke more than 10 cigarettes or use the equivalent tobacco- or nicotine-containing products per day * Receipt of blood products within 2 months prior to study * Donation of blood, plasma, or platelets prior to Screening * Poor peripheral venous access * Have previously completed or withdrawn from this study or any other study investigating risdiplam, and have previously received the investigational product Participants with Normal Hepatic Function Only: * Confirmed supine blood pressure \> 150 millimetre of mercury (mmHg) or \< 90 mmHg * Positive test for hepatitis B or C virus * Clinically significant abnormal laboratory values * Significant history or clinical manifestation of hepatic disorder * History or presence of liver disease or liver injury * Use or intend to use any prescription medications/products within 14 days prior to dosing -. Use or intend to use slow-release medications/products considered to still be active within 14 days prior to dosing * Use or intend to use any non-prescription medications/products within 7 days prior to dosing Participants with Hepatic Impairment Only: * Confirmed supine blood pressure \> 159 mmHg or \< 90 mmHg * Values outside the normal range for liver function tests that are not consistent with their hepatic condition * Use of a new medication, or a change in dose, for the treatment, or worsening of, hepatic encephalopathy * Use of prescription drugs within 14 days of study drug administration * Recent history of, or the treatment of, esophageal bleeding * Presence of a portosystemic shunt * Recent history of paracentesis * Current functioning organ transplant or are waiting for an organ transplant * Evidence of severe ascites * History or current symptoms of hepatic encephalopathy Grade 2 or above