Myelin is a specialized structure of the nervous system that both enhances 
electrical conductance and insulates neurons from external risk factors. In the 
central nervous system, polarized oligodendrocytes form myelin by wrapping 
processes in a spiral pattern around neuronal axons through myelin-related gene 
regulation. Since these events occur at a distance from the cell body, 
post-transcriptional control of gene expression has strategic advantage to 
fine-tune the overall regulation of protein contents in situ. Therefore, many 
research interests have been focused to identify RNA binding proteins and their 
regulatory mechanism in myelinating compartments. Fragile X mental retardation 
protein (FMRP) is one such RNA binding protein, regulating its target expression 
by translational control. Although the majority of works on FMRP have been 
performed in neurons, it is also found in the developing or mature glial cells 
including oligodendrocytes, where its function is not well understood. Here, we 
will review evidences suggesting abnormal translational regulation of myelin 
proteins with accompanying white matter problem and neurological deficits in 
fragile X syndrome, which can have wider mechanistic and pathological 
implication in many other neurological and psychiatric disorders.