A Study to Evaluate the Safety, Tolerability, and Effects on Blood and Urine Markers of Single Ascending Dose of GSK4771261 in Healthy Participants and Participants With Autosomal Dominant Polycystic Kidney Disease

Inclusion Criteria: For Part A * Body weight greater than or equal to (\>=) 45 kilograms (kg) and basal metabolic index (BMI) within the range 19.5 to 32 kilograms per square meters (kg/m\^2), inclusive * Capable of giving signed informed consent, * Participants who are overtly healthy as determined by medical evaluation by the investigator or a medically qualified designee based on medical history, physical examination, laboratory tests, and cardiac monitoring * Women must be of non-childbearing potential For Part B (planned Cohorts 1-3 and optional cohorts 4-5): * Body weight \>=45 kg and BMI within the range 19.5 to 32 kg/m\^2, inclusive. * Capable of giving signed informed consent, Confirmed diagnosis of Autosomal dominant polycystic kidney disease (ADPKD) by either applicable guidelines and/or genetic and imaging screening assessments * Participants diagnosed with ADPKD may have complications or comorbidities directly related to ADPKD but should be otherwise healthy as determined by the investigator or medically qualified designee based on a medical evaluation including medical history, physical examination, laboratory tests clinical testing * Confirmation of known ADPKD causal genetic mutation(s) at the Polycystic kidney disease (PKD)1 and/or PKD2 loci based on genetic testing at screening and/or existing genetic information collected during the participant's routine clinical care for ADPKD from a genetic testing provider that, in the judgement of the investigator, …