Editing Adrenoleukodystrophy (section)

===Gene therapy===
For patients where an appropriate match for a transplant cannot be found, there have been investigations into the use of [[gene therapy]].  Appropriate [[Vectors in Gene Therapy|vectors]] are selected and modified to express [[wild type]] ''ABCD1'', which is then transplanted into the patients using a similar procedure as for a bone marrow or stem cell transplant.<ref name="transplantreview"/>  Gene therapy has only been tried on a small number of patients, mainly in [[France]].  These patients were only considered for gene therapy after there was no [[Human leukocyte antigen|HLA match]] for a traditional transplant.  In two reported cases, the gene therapy was successful, with a resolution of the demyelination process up to two years after the procedure.  Although the gene therapy was successful in resolving the neurological symptoms, plasma VLCFA levels remained elevated.<ref name="transplantreview"/>

[[Elivaldogene autotemcel]] is pending authorization by the European Commission {{as of|May 2021|lc=yes}}. While this treatment is effective with 90% of patients being free of major functional disabilities after treatment, it costs $3.0 million per treatment and it comes with several adverse effects including mucositis and alopecia.<ref>{{Cite web |last=Liu |first=Angus |date=September 19, 2022 |title=A $3M gene therapy: Bluebird bio breaks its own pricing record with FDA approval of Skysona |url=https://www.fiercepharma.com/pharma/3m-gene-therapy-bluebird-breaks-own-record-fda-approval-skysona |access-date=November 1, 2023 |website=Fierce Pharma}}</ref><ref name="Skysona: Pending EC decision">{{cite web | title=Skysona: Pending EC decision | website=[[European Medicines Agency]] (EMA) | date=21 May 2021 | url=https://www.ema.europa.eu/en/medicines/human/summaries-opinion/skysona | access-date=1 June 2021 | archive-date=2 June 2021 | archive-url=https://web.archive.org/web/20210602214431/https://www.ema.europa.eu/en/medicines/human/summaries-opinion/skysona | url-status=live }}</ref><ref>{{cite press release | title=Bluebird Bio Receives Positive CHMP Opinion for Skysona (elivaldogene autotemcel, Lenti-D) Gene Therapy for Patients Less Than 18 Years of Age with Early Cerebral Adrenoleukodystrophy (CALD) | publisher=Bluebird Bio | via=Business Wire | date=21 May 2021 | url=https://www.businesswire.com/news/home/20210521005242/en/bluebird-bio-Receives-Positive-CHMP-Opinion-for-SKYSONA%E2%84%A2-elivaldogene-autotemcel-Lenti-D%E2%84%A2-Gene-Therapy-for-Patients-Less-Than-18-Years-of-Age-with-Early-Cerebral-Adrenoleukodystrophy-CALD | access-date=1 June 2021 | archive-date=2 June 2021 | archive-url=https://web.archive.org/web/20210602215413/https://www.businesswire.com/news/home/20210521005242/en/bluebird-bio-Receives-Positive-CHMP-Opinion-for-SKYSONA%E2%84%A2-elivaldogene-autotemcel-Lenti-D%E2%84%A2-Gene-Therapy-for-Patients-Less-Than-18-Years-of-Age-with-Early-Cerebral-Adrenoleukodystrophy-CALD | url-status=live }}</ref><ref name="SPS">{{cite web | title=Elivaldogene autotemcel | website=SPS - Specialist Pharmacy Service | date=28 May 2021 | url=https://www.sps.nhs.uk/medicines/elivaldogene-autotemcel/ | access-date=1 June 2021 | archive-date=2 June 2021 | archive-url=https://web.archive.org/web/20210602214726/https://www.sps.nhs.uk/medicines/elivaldogene-autotemcel/ | url-status=live }}</ref> There are also reports of hematologic cancer development in patients receiving this gene therapy, including myelodysplastic syndrome and acute myeloid leukemia.<ref>N Engl J Med 2024;391:1287-1301, DOI: 10.1056/NEJMoa2405541</ref>