CLN5 is a form of Batten Disease, a neurodegenerative disorder in children causing psychomotor regression, seizures, blindness, loss of ambulation and premature death, and has no available treatments.

The purpose of this study is to investigate the clinical characteristics and natural clinical progression of symptoms in individuals with CLN5. This natural history study is important to better understand disease course to be able to determine clinically relevant outcome measures for use in future clinical trials.

Neuronal Ceroid Lipofuscinosis (NCL) are comprised of a group of fatal neurodegenerative diseases caused by mutations in an enzyme or protein which results in the accumulation of toxic deposits in the eye, brain, skin, muscle and other cells.

CLN5 is a type of NCL, caused by homozygous or bi-allelic heterozygous variants in the CLN5 gene. Lack of CLN5 protein impairs the breakdown of certain proteins, leads to defective lysosomal trafficking, resulting in accumulation of toxic material and subsequent cell damage. CLN5 disease presents in childhood with neurological findings including motor clumsiness and attention disturbances, followed by progressive visual failure, psychomotor depression, epilepsy, and premature death.

No investigational product will be provided in the study.

Inclusion Criteria:

1. Age at disease onset of ≤ 5 years of age.
2. Molecular genetic diagnosis confirming the presence of pathogenic or likely pathogenic variant(s) on both alleles (biallelic) of the CLN5 gene.

For Prospective Arm only:

1. Subject age of ≤ 9 years.
2. Hamburg motor and vision score of ≥ 1 at time of consent.
3. Subject must have a caregiver available to support the subject and attend visits with the subject.

Exclusion Criteria - All Subjects:

1. Has another neurologic disease or illness that may have caused cognitive decline before study entry.
2. Has a known pathogenic or clinically suspected mutation in a seizure associated genetic mutation besides CLN5.
3. Any prior participation in a study in which a gene therapy vector or stem cell transplantation was administered.
4. Participation in other investigational studies and non-interventional studies that have similar study assessments as this protocol while the subject is enrolled in this study is prohibited.

Patients with a confirmed genetic diagnosis of CLN5.