The major findings of this cohort of Latin American patients with atypical CLN2 were: (i) median age at symptom onset was 6 years; (ii) the most common first symptoms were seizures (47%), followed by language abnormalities (20%) and by behavioural abnormalities (17%); (iii) during the disease course, the most common symptoms were: language difficulty (100% of patients); cognitive impairment (93%), seizures and ataxia (90%, each) and (iv) three novel mutations were found in the studied population. This evidence concerns the gene TPP1 and Cognitive impairment.