Inclusion Criteria:
* 1-18 years of age
* Clinically symptomatic patients with diagnosis of CLN7 based upon molecular testing with homozygous or compound heterozygous and pathogenic mutations in MFSD8 gene with symptom onset before age 4
* Patients selected to be included in this study will have no more than moderate severity of the disease and will have to meet the following criteria; Not dependent on chronic invasive ventilatory support AND have either
* Expressive language sub test on Mullen and/or Vineland consistent with an age equivalent score of a 2 year 0 month old. This means they should have 20-50 words (all comprehensible) in their vocabulary and putting 2-3 words phrases in a sentence or,
* Patients can complete and obtain a score of 2-3 on GMFM sub domain E (Walking, Running \& jumping) item 67 (ie With 2 hands held can walk 10 steps forward)
* Written informed consent provided by participant/parent/guardian and willingness to participate and comply with all the study related visits and procedures. Assent provided by children 10 -17 years old based on their ability to understand the risks and possible benefits, and the activities expected of them as participants.
Exclusion Criteria:
* Diagnosis of a second neurodegenerative disease or another genetic syndrome with a progressive course
* Hypersensitivity to any drugs used per procedural protocol
* Inability to tolerate anesthesia or study procedures
* Advanced stage disease defined by the use of chronic invasive ventilatory support (tracheostomy with ventilator dependence) and a non communicative status
* Concomitant illness that places patient at risk for gene transfer or gene transfer related procedures and immunosuppression
* Active, symptomatic viral infection (including but not limited to HIV or serology positive for Hepatitis B or C, or COVID-19) at the PI's discretion
* Bacterial infection requiring antibiotics within the 6 weeks prior to infusion
* New antiepileptic medications initiated within 90 days of infusion
* Status epilepticus within 30 days of infusion
* Generalized tonic-clonic seizure without returning to baseline within 24 hours of infusion
* Family is unwilling or unable to participate with required follow-up assessments
* Abnormal lab values that are clinically significant:
* Platelet count \< 100,000/mm3
* Abnormal absolute neutrophil count (ANC) of \< 1000/mm3
* Persistent leukopenia or leukocytosis (Total white blood cell count \< 3,000/mm or \> 15,000/mm respectively)
* Significant anemia (Hb \<10 g/dL)
* Abnormal prothrombin (PT) or partial thromboplastin time (PTT)
* Abnormal liver function tests (\>2 X ULN or \> 2 X the baseline value at time of dosing)
* Abnormal pancreatic enzymes (\>2 X ULN or \> 2 X the baseline value at time of dosing)
* Renal impairment defined as urinary protein concentration greater than or equal to 0.2 g/L on 2 consecutive tests
* Any other abnormal lab values that are clinically significant per PI's discretion
* If labs are abnormal, these can be rechecked during the screening period. If labs normalize with or without intervention, patient can be enrolled at the discretion of PI.
* Contraindications for intrathecal administration of the product via lumbar puncture, such as bleeding disorders or other medical conditions (e.g., spina bifida or clotting abnormalities)
* Contraindications for MRI scans (including but not limited to cardiac pacemaker, metal in the eye, aneurysm clip in the brain, etc.)
* History of or current chemotherapy, radiotherapy, or other immunosuppression therapy within 30 days preceding screening (corticosteroid treatment may be permitted at the discretion of the PI)
* Receipt of any other investigational agent within the previous 3 months
* Positive Beta hCG pregnancy test (females of child bearing potential will have a pregnancy test on Day -1)
* Any other medical condition that puts the subject at increased risk of adverse events related to the investigational product or study-related procedures.
