Examples of these are changes secondary to the accumulation of branched chain fatty acids such as phytanic acid, since the abnormal accumulation of this substance does not commence until after birth. The most striking example of post-developmental pathology is the distal axonopathy that occurs in adults with AMN, and appears attributable in some way to the accumulation of very long chain fatty acids. These studies have shown that DHA deprivation in rodents impairs spatial tasks and olfactory discrimination. The reversal learning task may prove a useful approach for the study of DHA adequacy, and may prove of great value for the definition of the role of DHA in normal human brain development. The peroxisomal defects of the Zellweger brain extend to the liver and kidney.
Several issues deserve further studies.