Inclusion Criteria:

Participants who fulfill the following criteria will be eligible for inclusion in this Registry Study.

• Participant must be treated with eli-cel in the post marketing setting at a center in the United States (US) that participates in the Registry Study.
• Participant must have provided an informed consent and/or assent to participate in Center for International Blood and Marrow Transplant Research (CIBMTR) registry.
• Participant must have provided an informed consent and/or assent to participate in the Registry Study.
• Participant must receive follow up care by a US-based physician with the ability to submit REG-502 data.

Registry Study Subpopulation inclusion:

Twenty-four of the 120 patients in the Registry Study must meet the following inclusion criteria which will be used to create the more advanced early active CALD subpopulation:

• Participant must meet the above inclusion criteria and have a Loes score of 4.5 through 9.0 with GdE+ (gadolinium enhancement positivity) from an MRI performed before treatment with eli-cel and with NFS of 0 or 1 at baseline.

Exclusion Criteria:

There are no exclusion criteria for this Registry Study.