Lysosomal storage disorders

The lysosomal storage disorders (LSD) are genetic diseases caused by deficiency of lysosomal enzymesor other lysosomal proteins that result in chronic and progressive storage of undegraded substrates thatare frequently present in the central nervous system. Neurocognition in LSD may be impaired with distinctregression or progressive slowing-down of development. The neurological phenotypes of LSD comprisesome specific neuropsychological profiles, including verbal and non-verbal learning disorders underlyingdysfunction of cerebral networks. Specific behavioural patterns and secondary psychiatric disorders mayalso occur. The knowledge of certain neuropsychological profiles and behavioural patterns in LSD maybe critical for recognition, early diagnosis, and intervention programming and monitoring. Developmentalanalysis in patients with LSD is hampered by concurrence of physical disability, sensory disturbances,and behavioural abnormalities. The assessment is currently based on evaluation of age-equivalent scoresin order to clinically understand developmental progress, stagnation, and loss of abilities in each individualdomain. The use of age-equivalent Vineland Adaptive Behaviour Scales is encouraged because of possiblediscrepancies between cognition and adaptive functioning in patients with impaired motor functions.Neurocognitive assessment of patients with LSD has become increasingly important to define the timingof possible interventions and clinical endpoints. This is crucial in view of emerging treatments of neurogeneticdisorders, especially neuronopathic LSD.