Pelizaeus Merzbacher Disease, also known as PMD, is a rare genetic disorder that primarily affects the central nervous system. It is characterized by the progressive degeneration of the white matter in the brain, leading to various neurological and developmental abnormalities. Though there are no precise synonyms for this condition, it can be referred to as "hypomyelinating leukodystrophy". This term emphasizes the defective myelin formation in the brain, which is the primary cause of PMD symptoms. Other related phrases could include "myelin disorder", "white matter degeneration" or "neurological leukodystrophy". While these terms may not be exact substitutes for PMD, they provide a clearer understanding of the condition and its significant characteristics.