Chronic GM1 gangliosidosis presenting as dystonia: clinical and biochemical studies in a new case.

Clinical and biochemical findings in a patient affected by chronic GM1 gangliosidosis, presenting as progressive dystonia and mental deterioration, are reported. The patient, a 13-year-old male, showed, at the age of 3 years, an impairment of gait with frequent falls, dysarthria and stuttering. At the age of 6, writing dystonia appeared and subsequently mental deterioration and dystonic postures of arms and legs became evident. The clinical features presented by this patient are similar to those shown by the cases of adult/chronic GM1 gangliosidosis previously reported, except for the early onset. This observation emphasizes the occurrence of dystonia as prominent symptom in chronic GM1 gangliosidosis, underlining that this disease must be considered in the diagnostic approach to the progressive dystonias of the early infancy.