81-87. DOI: 10.21508/102781-87. DOI: 10.21508/ -4065-2017 Last years in children we observe high frequency of diseases, associated with focal central nervous system damage by infectious, autoimmune and congenital process. Very often the process occurs in children of early age as a result of recurrent and congenital (chronical) infections. Differential diagnosis of demyelinative central nervous system disease can be difficult, so we report about the case of progredient X-associated adrenoleucodystrophy in 4-year-old child, case was verified genetically. We suppose differential diagnostics with geneticallyassociated exchange disorders (and myelinization disorders) in all cases of progredient disease with lose of skills and abilities, convulsive syndrome progression on the background trigger somatic or infectious pathology, progressive diffuse brain demyelination and increasing of atrophic processes without inflammatory signs in cerebrospinal fluid, differential diagnosis with genetically determined disorders of metabolism in children of all age groups. We also insist on a therapy while making differential diagnosis. We suggest the diagnosis for the therapy start is encephalitis or congenital central nervous system infection. In such cases we can start causal therapy (antiviral or antibacterial), antiinflamatory, antioxidant therapy, metabolical therapy, respiratory support to make the situation stable.Key words: children, nervous system demyelinative diseases, encephalitis, Х-associated adrenoleucodystrophy.