Expanded Access Program (EAP) of Levacetylleucine for Ataxia-Telangiectasia (A-T)

Inclusion Criteria: 1. Patient has a genetically confirmed diagnosis of Ataxia-Telangiectasia, a rare and serious disease with no alternative approved treatments. 2. Patient and/or their legal representative signed a written informed consent and, if applicable, written assent. 3. Patient weighs ≥15 kg. 4. If female and of reproductive potential, the treating physician verified the patient is not pregnant prior to enrollment and will use adequate contraceptive methods to avoid pregnancy during and up to 7 days after participating in the program. 5. Patient resides in the United States at time of enrollment and throughout the duration of their participation in the EAP. Exclusion Criteria: 1. Patient is enrolled in or early withdrew participation from a clinical trial with levacetylleucine for A-T. 2. Patient is pregnant, breastfeeding, or considering pregnancy. 3. Patient has a physical, cognitive, psychiatric condition, or an active or suspected malignancy that, in the judgment of the treating physician, may pose a safety risk or interfere with the patient's ability to comply with the EAP procedures. 4. Patient is receiving N-acetyl-DL-leucine or N-acetyl-D-leucine and is unwilling to stop use throughout the duration of their participation in the EAP. 5. Patient is receiving another investigational drug for any reason.