for people ages 2-18 (full criteria)
at Oakland, California and other locations
study started
completion around
Principal Investigator
by Alexander Fay, MD



A non-randomized, open-label, dose escalation study of a single intracerebroventricular (ICV) administration of a gene replacement therapy in subjects who are 2 to 18 years old with NGLY1 Deficiency.

Official Title

A Phase 1/2/3 Open-label, Single Arm, Dose-finding Study to Investigate Long-term Safety, Tolerability and Efficacy of GS-100, an Adeno-associated Virus Serotype 9 (AAV9) Vector-mediated Gene Transfer of Human NGLY1, in Patients With NGLY1 Deficiency


This study is a first in human (FIH) open-label, dose escalation study designed to assess the safety and efficacy of administration of an adeno-associated viral vector serotype 9 (AAV9) carrying the gene encoding N-glycanase 1 (NGLY1) in subjects with NGLY1 Deficiency. The study treatment will be delivered via intracerebroventricular (ICV) injection. All outcomes (primary, secondary, exploratory) will be assessed at 52 weeks. Safety will be monitored continuously throughout the study for adverse / serious adverse events and dose limiting toxicities. Efficacy outcomes will be assessed at baseline and 52 weeks. The co-primary outcomes will be change from baseline in cerebrospinal fluid (CSF) GlcNAc-Asn (GNA, or N-acetylglucosamine), the NGLY1 Deficiency biomarker, and change in motor subdomain on the Bayley Scales of Infant and Toddler Development (BSID-4). Secondary outcomes will include weight (Z-score), clinical and caregiver impressions of change, and other neurocognitive assessment tools. Exploratory outcomes will include brain volumes as measured by magnetic resonance imaging (MRI), quality of life assessments (including sleep habits), liver function test results, and lacrimation assessments. Each participant will be followed for safety and efficacy for 5 years after treatment.


NGLY1 Deficiency, Gene Therapy, Intervention study, Infusions, Intraventricular, Biomarker, Enzyme Replacement Therapy, Congenital Disorders of Glycosylation


You can join if…

Open to people ages 2-18

  • Patients must be 2 to 18 years of age, inclusive, at the time of signing the informed consent form (ICF)
  • Patients with a confirmed diagnosis of NGLY1 Deficiency based on detection of biallelic pathogenic variants in the NGLY1 gene via commercially available molecular genetic sequencing
  • Patients with at least one of the following signs or symptoms:
    1. Global developmental delay and/or intellectual disability
    2. Hyperkinetic movement disorder
    3. Transient elevation of transaminases
    4. (Hypo)alacrima
    5. Peripheral neuropathy
  • For patients with epilepsy who require anti-seizure medications for seizure control: must be on a stable regimen for 28 days prior to enrollment
  • Patients willing and capable per investigator opinion to comply with study procedures and requirements
  • Females of childbearing potential must have a negative serum pregnancy test at screening and must agree to use an acceptable method of highly effective contraception from screening through the end of the study
  • Patients or parent(s)/guardian(s) must be willing and able to provide written consent after the nature of the study has been explained and prior to performance of any research-related procedures

You CAN'T join if...

  • Patients at Level 5 of both the Gross Motor Function Classification System Expanded and Revised (GMFCS E&R) and the Communication Function Classification System (CFCS) scales as assessed by the investigator
  • Contraindication to use of corticosteroids or history of a condition that could worsen with corticosteroid therapy, as assessed, and determined by the investigator
  • Signs / symptoms of increased intracranial pressure (ICP), history of space occupying lesion, or ventricular shunt that would preclude ICV procedures or safety assessments
    1. If clinical signs or symptoms of increased ICP are present (such as headache, vomiting, altered mental status), an ophthalmology examination will be performed to assess for papilledema and/or venous pulsations
  • Have active malignancy (except non-melanoma skin cancer), autoimmune, metabolic (i.e., diabetes), hematologic, cardiac, or renal disease, or uncontrolled epilepsy, that is of clinical significance defined as requiring regular medical attention or treatment
  • Vital signs outside age-based normative values:
    1. Blood pressure: values > 99th percentile as cited in the National Heart, Lung and Blood Institute (NHLBI) guidelines for blood pressure levels based on subject's age, height and sex (
    2. Temperature: evidence of fever such as body temperature (e.g., orally measured) of 38.0°C (100.3°F)
    3. Respiratory rate in breaths per minute: toddler (1-3 years old): 24-40; preschooler (4-5 years old): 22-34 breaths per minute; school-aged child (6-12 years old): 18-30 breaths per minute; adolescence (13-18 years old): 12-16.
    4. Oxygen saturation on room air < 92%
  • Any condition that in the opinion of the investigator or the study medical monitor would prevent the patient from fully complying with the requirements of the study (including the corticosteroid treatment outline in the protocol) and/or would impact or interfere with the evaluation and interpretation of patient safety or efficacy results
  • Known allergy or hypersensitivity to the GS-100 investigational product formulation
  • Prior treatment with gene therapy
  • Treatment with any investigational product (IP) within 30 days or 5 half-lives of the IP, whichever is longer, prior to screening period. For patients who have received a prior investigational product, all ongoing AEs experienced while receiving the investigational product must have been resolved prior to screening for this study
  • Concurrent enrollment in another clinical study, unless it is an observational (non-interventional) clinical study that does not interfere with the requirements of the current protocol and does not have the potential to impact the evaluation of safety and efficacy of GS-100
  • Liver dysfunction at screening as defined by the following
    1. ALT: > 3 x upper limit of normal (ULN)
    2. aspartate aminotransferase (AST): > 3 x ULN
    3. INR: ≥1.4 x ULN
    4. Total bilirubin: > 2 x ULN unless Gilbert's syndrome is documented
  • Any current infection with hepatitis B virus (HBV) as evidenced by positive HBV surface antigen (HBsAg), and/or HBV core antibody (HBcAb) at screening. Isolated HBsAb positivity for HBV vaccination in conjunction with negative confirmatory HBV DNA testing at screening is not exclusionary
  • Any prior or current infection with hepatitis C virus (HCV) as evidenced by positive HCV antibody testing and confirmed by positive polymerase chain reaction (PCR) RNA testing at screening
  • Any of the following abnormal laboratory values:
    1. Hemoglobin level: < 9 g/dL
    2. Absolute neutrophil count: < 1000 cells/microliter
    3. Platelet count: < 100,000/mm3
    4. Creatinine: > 1.25 x ULN
  • Have a major surgery planned during the screening period through 52 weeks following GS-100 infusion, including major dental procedures (e.g., wisdom tooth extraction)
  • Pregnant or breastfeeding female patient
  • Patients that demonstrate elevated serum adrenocorticotropic hormone (ACTH) 1.5 times the upper limit of normal for the reference range must be referred for consultation with a pediatric endocrinologist to rule out primary adrenal insufficiency prior to being enrolled into the study. Patients may re-screen for participation in the study after medical consultation and / or possible treatment has been initiated to address any adrenal insufficiency


  • Oakland Children's Hospital (UCSF Benioff) accepting new patients
    Oakland California 94609 United States
  • Texas Children's Hospital (Baylor College of Medicine) accepting new patients
    Houston Texas 77030 United States

Lead Scientist at UCSF

  • Alexander Fay, MD
    Associate Professor, Neurology, School of Medicine. Authored (or co-authored) 15 research publications


accepting new patients
Start Date
Completion Date
Grace Science, LLC
Phase 1/2 NGLY1 Deficiency Research Study
Study Type
Expecting 12 study participants
Last Updated