|The black portions in the middle of this ADL brain are
where demyelination has occurred. White matter normally
appears white in MRIs, like in the bottom half of this brain.
(Image via Wikimedia Commons)
ALD is a consequence of a mutation in the ABCD1 gene located on the X chromosome, the maternally inherited sex chromosome. The gene codes for a transport protein responsible for conveying VLCFAs to peroxisomes where they are broken down and disposed of by the cell. The mutated protein is unable to transport VLCFAs, leading to fatty acid build up in nervous tissue. When this occurs, VLCFAs interact with the myelin and cause this crucial insulator to degrade, thereby slowing nervous signals and crippling the adrenal gland.