Introduction: Late infantile neuronal ceroid lipofuscinosis type 2 (CLN2), is a neurodegenerative autosomal recessive disease caused by TPP1 gene variants, with a spectrum of classic and atypical phenotypes. The aim of treatment is to slow functional decline as early as possible, improving quality of life and survival. This study describes the clinical characteristics as well as response to treatment with cerliponase alfa. Materials and Methods: A retrospective study was conducted in five Latin-American countries, based on clinical records from patients with CLN2. Clinical follow-up and treatment variables are described. A descriptive and bivariate statistical analysis was performed. Results: A total of 36 patients are reported with a mean age of symptom onset and time to first specialized consultation of 4.7±2.3 and 6±3.1 years, respectively. Seizures were the predominant symptom (80.6%). In a subgroup analysis, most patients with the classic phenotype exhibited regression in language (90%), while the patients with the atypical phenotype had seizures as the predominant symptom (87%). The mean age of symptom onset and time to first specialized consultation was 3.5±2.0 and 4.9±3.2 years, respectively, in patients with the classic phenotype and 6.2±1.8 and 7.5±2.4 in patients with the atypical phenotype. The mean time interval between onset of symptoms and treatment initiation was 3.8 years in patients with classic phenotype and 7.4 in patients with atypical phenotype. All patients were treated with cerliponase alfa, maintaining overall functional stability as compared to pretreatment values. Discussion and conclusion: This study reports at this time the largest number of patients with CLN2 in treatment with cerliponase alfa in the world. Data show a higher frequency of patients with atypical phenotype and a high allelic proportion of intron variants in our region. There was evidence of long intervals until first specialized consultation, diagnosis, and enzyme replacement therapy. Follow-up after the initiation of cerliponase alfa showed slower-to-no-progression of the disease, associated with adequate clinical outcomes and stable functional scores. These improvements were consistent in both clinical phenotypes.
