Investigations of Juvenile Neuronal Ceroid Lipofuscinosis

* INCLUSION CRITERIA: For the Main and Sub-Studies, participants \> 1 week of age, of all genders, demographics, geographic locations, and disease severity will be recruited in order to obtain cross-sectional representation of CLN3-related conditions (Main and Sub-Studies) or all NCLs (Sub-Study B). Participants in the Main study will be followed at approximately yearly intervals to obtain longitudinal data. Participants in Sub-Study A may elect to send in medical records and samples only, or to come to the NIH for evaluations as outlined in Section 4. We anticipate that participants in Sub-Study B will be seen mostly at NCL/CLN3-related family conferences. Main Study: Individuals \> 1 week of age with a diagnosis of CLN3 or a CLN3-related/other NCL-type condition. Diagnosis determined by one of the following: 1. Two CLN3 or NCL condition-appropriate genetic mutations 2. One CLN3 mutation AND i) clinical presentation suggestive of CLN3, OR ii) characteristic electron microscopy (EM) findings (such as curvilinear body, fingerprint profile, granular osmiophilic deposits). Sub-Study A: Individuals \> 1 week of age with a diagnosis of CLN3 or CLN3-related/other NCL-type condition. Diagnosis determined by one of the following: 1. Two CLN3 or condition-appropriate genetic mutations 2. One CLN3 mutation AND i) clinical presentation suggestive of CLN3, OR ii) characteristic electron microscopy (EM) findings (such as curvilinear body, fingerprint profile, granular osmiophilic deposits). OR Individuals \> 1 month of age who have family member(s) diagnosed with CLN3 or CLN3-related/other NCL-type condition. Sub-Study B: Individuals \> 1 week of age with a clinical diagnosis of CLN3 or NCL. OR Individuals \> 1 month of age who have family member(s) diagnosed with CLN3 or NCL. EXCLUSION CRITERIA: Main Study: 1. Individuals who cannot travel to the NIH because of their medical condition. 2. Individuals who, in the opinion of the Investigator, are unable to comply with the protocol or have medical conditions that would potentially increase the risk of participation. 3. Females who are pregnant. Sub-Studies A and B: 1. Unaffected individuals \> 18 years of age who have cognitive impairments. 2. Individuals who, in the opinion of the Investigator, are unable to comply with the protocol or have medical conditions that would potentially increase the risk of participation.