The OLE, expected to begin in Q1 2024, will include those who completed treatment in the phase 2 dose exploration trial or a prior trial of CTI-1601. In the OLE, investigators will assess safety, tolerability, and pharmacokinetics of the agent, as well as measures of frataxin (FXN) levels and other pharmacodynamic markers. Other objectives include the evaluation of the effects of long-term subcutaneous administration of CTI-1601 on measures of clinical function. Data from the OLE will be compared with a matched set of untreated patients from the Friedreich’s Ataxia Clinical Outcome Measures Study (FACOMS) database.