 Metachromatic Leukodystrophy MLD is a rare autosomal recessive disorder caused by the deficiency of the Arylsulfatase A enzyme ARSA, resulting in accumulation of galactosyl sulfatide cerebroside sulfate, a major constituent of the myelin sheath. Accumulation of sulfatides leads to a progressive degeneration of the white matter in the central and peripheral nervous systems CNS, PNS and to a neuronal degeneration. The late-infantile form of MLD, which is usually diagnosed in the second year of life, is the most frequent and severe form of the disease. The prognosis is severe, leading to vegetative stage or death within few years after the diagnosis. There is no treatment for patients affected with this early-onset form of the disease. 