LEUCO J ITS TROPHYLeucodystrophy refers to progressive degeneration of the white matter of the brain clue to imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fibre. Myelin which lends its color to the white matter of the brain, is a complex substance made up of at least ten different chemicals. The leucodystrophy are a group of disorders that are caused by genetic defects in hoW myelin produces or metabolizes these chemicals. Each of the leucodystrophies in the result of a defect in the gene that controls one (and only one) of the chemicals. Specific leusodystrophies include - Metachroinatic leucodystrophy          ❑ Adrenoleucodystrophy                                ​❑ Canavan diseaseKrabbe's disease                                                 ❑ Pelizaeus-Merzhacher disease                                                         ​ ❑ Alexander diseaseSymptoms vary according to the specific type of leucodystrophy and may be difficult to recognize in the early stages of the disease.Canavan's diseaseAutosomal recessive disorder Caused due to deficiency of the enzyme N-Aspertoacylase. This leads to accumulation of N-Acetyl aspartic acid in brain and urine. It is characterized by the clinical traid of --> Hypotonia, Head lag, Macrocephaly​​AdrenoleucodvstrophyX-linked recessive disorder Caused due to deficiency of AcyI-C'oA synthetase. Onset is about 5-10 years Main symptoms are ataxia, spasticity, motor deficits, cortical blindness. Marocephaly is not a key feature Metachromatic leucodystrophy Autosomal recessive disorder Caused due to Arylsulfatase A deficiency Onset is in the 2nd year. Symptoms are into-ordination, especially gait disturbance, then general regression, optic atrophy, combined upper and lower motor neuron signs. Marocephaly usually late. Krabbe leucodvstrophy Autosomal recessive Caused due to deficiency of Beta-galactosidase deficiency Onset is in the first 6 months of life Optic atrophy, spasticity Head often small