This is a multicenter, observational study for patients with a confirmed diagnosis of neuronal ceroid lipofuscinosis type 2 (CLN2 disease), also known as TPP1 deficiency, who intend to be or are currently being treated with cerliponase alfa. Patients receiving or expected to receive cerliponase alfa within 60 days of signing the informed consent form (ICF) may be eligible to enroll in the study, assuming all regulatory requirements for sites that have agreed to participate and protocol inclusion criteria are met. Data may be collected for all or some of the assessments as outlined in the protocol, dependent upon the clinic's and/or individual patient's standard of care.

Inclusion Criteria:

1. Diagnosed with CLN2 disease.
2. Currently receiving or plan to begin treatment with cerliponase alfa.
3. Written informed consent/assent obtained.

Exclusion Criteria:

1. Currently receiving treatment in another investigational device or drug study.

CLN2 patients who are currently taking or intend to take cerliponase alfa within 60 days of signing the informed consent form.