Metachromatic leukodystrophy (MLD) is a rare genetic disorder that affects the nervous system and the ability to move. It is caused by a deficiency of the enzyme arylsulfatase A, which leads to the accumulation of fatty substances called sulfatides in the brain and other tissues. This buildup damages the protective covering of nerve fibers, known as myelin, resulting in progressive neurological decline. Symptoms of MLD typically appear in childhood, including loss of motor skills, difficulty walking, and cognitive decline. There are different forms of MLD, including late-infantile, juvenile, and adult types, each with varying onset and severity. Early diagnosis and supportive care are essential for managing the condition.