An observational study in Glycogen Storage Disease Type IA and Von Gierke's Disease (GSD Type Ia), sponsored by Ultragenyx Pharmaceutical Inc. Completed at 6 sites in 4 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-18.
Sponsored by Ultragenyx Pharmaceutical Inc · Observational
The primary objective of this study is to determine the long-term safety of DTX401 following a single intravenous (IV) dose in adults with GSDIa.
Only participants who received DTX401 in study 401GSDIA01 (NCT03517085) are eligible to participate in study 401GSDIA02. No investigational product will be administered during study 401GSDIA02. Participants will be followed in study 401GSDIA02 for at least 4 years, and up to 6 years after administration of DTX401.
361 studies on the registry are indexed under Glucose Metabolism Disorders; 38 are open to participants now.
This study's enrollment of 12 is below the median of 87 across 47 observational studies indexed under Glucose Metabolism Disorders.
Browse Glucose Metabolism Disorders studies →Ultragenyx Pharmaceutical Inc is the lead sponsor of 63 studies on the registry; 8 are open to participants now.
Of its 16 completed or terminated interventional studies of FDA-regulated products, 12 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Subjects 18 years of age or older with GSDIa previously enrolled in 401GSDIA01.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants received a single intravenous (IV) dose of 2.0 × 10\^12 GC/kg DTX401(pariglasgene brecaparvovec) with a reactive steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
Participants received a single IV dose of 6.0 × 10\^12 GC/kg DTX401(pariglasgene brecaparvovec) with a reactive steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
Participants received a single IV dose of 6.0 × 10\^12 GC/kg DTX401(pariglasgene brecaparvovec) with an optimized reactive steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
Participants received a single IV dose of 6.0 × 10\^12 GC/kg DTX401(pariglasgene brecaparvovec) with a prophylactic steroid regimen during their participation in study 401GSDIA01 (NCT03517085). No intervention was provided during the 401GSDIA02 long term follow up study.
Other: No intervention
No intervention
Number of Participants With Treatment Emergent Adverse Events (TEAEs), Serious TEAEs and Discontinuations Due to TEAEs
An adverse event (AE) is defined as any untoward medical occurrence, regardless of its causal relationship to study product. A TEAE is defined as any AE not present prior to the initiation of the drug treatment or any AE already present that worsens in either intensity or frequency following exposure to the drug treatment. A serious TEAE is an AE that meets any of the following criteria in the view of either the Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/Incapacity; congenital anomaly/birth defect not present at screening; other important medical events. Severity of events were graded as mild (grade 1), moderate (grade 2), severe (grade 3), life-threatening (grade 4), or death (grade 5). As DTX401 was administered as part of Study 401GSDIA01, all AEs in Study 401GSDIA02 were considered TEAEs.
Time frame: From Baseline (Week 52 of 401GSDIA01/Visit 1 of 401GSDIA02) Up to Week 329
Change From Baseline in Time to First Hypoglycemic Event During a Controlled Fasting Challenge Over Time
The change from baseline in time (in hours) to first hypoglycemic event (defined as glucose \< 54 mg/dL \[\< 3.0 mmol/L\]) during a controlled fasting challenge at the participant's last visit. A positive change from baseline is favorable. Change from baseline is calculated from Baseline (Week 0) of the 401GSDIA01 study.
Time frame: Baseline (Week 0 of 401GSDIA01), Weeks 52 (Visit 1 of 401GSDIA02), 78, 104, 130, 156, 182, 208, 234, 260, Last Visit (Up to Week 329)
All 12 participants were dosed with DTX401 in study 401GSDIA01 (NCT03517085); after completing 52 weeks of follow-up in study 401GSDIA01, they subsequently enrolled in study 401GSDIA02 for an overall mean study duration of 276.2 weeks.
| Milestone | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 |
|---|---|---|---|---|
| Started | 3 | 3 | 3 | 3 |
| Completed | 3 | 3 | 2 | 3 |
| Not completed | 0 | 0 | 1 | 0 |
| Withdrew: Withdrawal by subject | 0 | 0 | 1 | 0 |
An adverse event (AE) is defined as any untoward medical occurrence, regardless of its causal relationship to study product. A TEAE is defined as any AE not present prior to the initiation of the drug treatment or any AE already present that worsens in either intensity or frequency following exposure to the drug treatment. A serious TEAE is an AE that meets any of the following criteria in the view of either the Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/Incapacity; congenital anomaly/birth defect not present at screening; other important medical events. Severity of events were graded as mild (grade 1), moderate (grade 2), severe (grade 3), life-threatening (grade 4), or death (grade 5). As DTX401 was administered as part of Study 401GSDIA01, all AEs in Study 401GSDIA02 were considered TEAEs.
| Participants | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 |
|---|---|---|---|---|
| TEAE | 3 | 3 | 3 | 3 |
| Related TEAE | 0 | 2 | 0 | 2 |
| Serious TEAE | 2 | 1 | 2 | 2 |
| Serious Related TEAE | 0 | 0 | 0 | 1 |
| TEAE with Maximum Severity Grade 5 | 0 | 0 | 0 | 0 |
| TEAE with Maximum Severity Grade 4 | 0 | 1 | 0 | 1 |
| TEAE with Maximum Severity Grade 3 | 1 | 0 | 1 | 1 |
| TEAE with Maximum Severity Grade 2 | 2 | 1 | 2 | 0 |
| TEAE with Maximum Severity Grade 1 | 0 | 1 | 0 | 1 |
| Grade 3 or 4 TEAE | 1 | 1 | 1 | 2 |
| Related Grade 3 or 4 TEAE | 0 | 0 | 0 | 1 |
| TEAE Leading to Study Discontinuation | 0 | 0 | 0 | 0 |
| TEAE Leading to Death | 0 | 0 | 0 | 0 |
The change from baseline in time (in hours) to first hypoglycemic event (defined as glucose \< 54 mg/dL \[\< 3.0 mmol/L\]) during a controlled fasting challenge at the participant's last visit. A positive change from baseline is favorable. Change from baseline is calculated from Baseline (Week 0) of the 401GSDIA01 study.
| hours | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 |
|---|---|---|---|---|
| Change at Week 52 | 4.19 ± 2.24 | -1.78 ± 1.71 | -0.59 ± 0.06 | 3.64 ± 2.66 |
| Change at Week 78 | 3.06 ± 3.96 | -1.78 ± 1.80 | 3.21 ± 4.30 | 2.46 ± 3.53 |
| Change at Week 104 | 9.17 ± 1.56 | -0.45 ± 1.93 | 4.02 ± 2.25 | 2.33 ± 3.13 |
| Change at Week 130 | 8.23 ± 1.91 | 0.60 ± 0.31 | 5.12 ± 3.94 | 6.33 |
| Change at Week 156 | 9.80 ± 2.28 | -0.22 ± 2.32 | 4.29 ± 4.06 | 5.88 ± 2.05 |
| Change at Week 182 | 7.91 ± 4.33 | — | 2.68 | — |
| Change at Week 208 | 8.17 ± 3.08 | 1.46 ± 1.63 | 3.92 ± 3.51 | 2.29 ± 2.59 |
| Change at Week 234 | 8.41 ± 3.92 | — | — | — |
| Change at Week 260 | 8.08 ± 3.64 | 0.76 ± 0.45 | 3.58 ± 2.61 | — |
| Change at Last Visit | 8.08 ± 3.64 | 0.76 ± 0.45 | 3.58 ± 2.61 | 2.29 ± 2.59 |
Collected over All AEs were collected from signing of informed consent (Visit 1, ie, Week 52 of 401GSDIA01) through the Last Visit (up to Week 329). SAEs were collected for up to 30 days after the Last Visit.. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| DTX401 Cohort 1 | 0/3 (0%) | 2/3 (66.7%) | 3/3 (100%) |
| DTX401 Cohort 2 | 0/3 (0%) | 1/3 (33.3%) | 3/3 (100%) |
| DTX401 Cohort 3 | 0/3 (0%) | 2/3 (66.7%) | 3/3 (100%) |
| DTX401 Cohort 4 | 0/3 (0%) | 2/3 (66.7%) | 3/3 (100%) |
| Event | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 |
|---|---|---|---|---|
| Abdominal PainGastrointestinal disorders | 2/3 | 0/3 | 0/3 | 0/3 |
| Abdominal Pain UpperGastrointestinal disorders | 1/3 | 0/3 | 0/3 | 0/3 |
| DiarrhoeaGastrointestinal disorders | 1/3 | 0/3 | 0/3 | 0/3 |
| VomitingGastrointestinal disorders | 1/3 | 0/3 | 0/3 | 0/3 |
| Multiple Organ Dysfunction SyndromeGeneral disorders | 0/3 | 1/3 | 0/3 | 0/3 |
| CellulitisInfections and infestations | 0/3 | 1/3 | 0/3 | 0/3 |
| Covid-19Infections and infestations | 1/3 | 0/3 | 0/3 | 1/3 |
| Escherichia InfectionInfections and infestations | 1/3 | 0/3 | 0/3 | 0/3 |
| GastroenteritisInfections and infestations | 0/3 | 0/3 | 0/3 | 1/3 |
| Gastroenteritis NorovirusInfections and infestations | 1/3 | 0/3 | 0/3 | 1/3 |
| Event | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 |
|---|---|---|---|---|
| Covid-19Infections and infestations | 2/3 | 2/3 | 3/3 | 2/3 |
| VomitingGastrointestinal disorders | 2/3 | 2/3 | 1/3 | 1/3 |
| FatigueGeneral disorders | 2/3 | 0/3 | 1/3 | 1/3 |
| Animal BiteInjury, poisoning and procedural complications | 2/3 | 0/3 | 0/3 | 0/3 |
| HypertriglyceridaemiaMetabolism and nutrition disorders | 1/3 | 1/3 | 0/3 | 2/3 |
| HypoglycaemiaMetabolism and nutrition disorders | 2/3 | 1/3 | 1/3 | 0/3 |
| Back PainMusculoskeletal and connective tissue disorders | 2/3 | 0/3 | 2/3 | 0/3 |
| Musculoskeletal PainMusculoskeletal and connective tissue disorders | 2/3 | 0/3 | 0/3 | 0/3 |
| MyalgiaMusculoskeletal and connective tissue disorders | 2/3 | 0/3 | 0/3 | 0/3 |
| HeadacheNervous system disorders | 2/3 | 0/3 | 1/3 | 1/3 |
| Age, Categorical(Participants) | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 | Total |
|---|---|---|---|---|---|
| <=18 years | 0 | 0 | 0 | 0 | 0 |
| Between 18 and 65 years | 3 | 3 | 3 | 3 | 12 |
| >=65 years | 0 | 0 | 0 | 0 | 0 |
| Age, Continuous(years) | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 | Total |
|---|---|---|---|---|---|
| Mean | 45.3 ± 15.3 | 29.7 ± 10.1 | 26.0 ± 13.9 | 25.0 ± 5.2 | 31.5 ± 13.2 |
| Sex: Female, Male(Participants) | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 | Total |
|---|---|---|---|---|---|
| Female | 1 | 0 | 2 | 1 | 4 |
| Male | 2 | 3 | 1 | 2 | 8 |
| Ethnicity (NIH/OMB)(Participants) | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 | Total |
|---|---|---|---|---|---|
| Hispanic or Latino | 0 | 1 | 0 | 0 | 1 |
| Not Hispanic or Latino | 3 | 2 | 3 | 3 | 11 |
| Unknown or Not Reported | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 | Total |
|---|---|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 | 0 | 0 |
| Asian | 0 | 0 | 0 | 0 | 0 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 | 0 | 0 |
| Black or African American | 0 | 0 | 0 | 0 | 0 |
| White | 3 | 3 | 3 | 3 | 12 |
| More than one race | 0 | 0 | 0 | 0 | 0 |
| Unknown or Not Reported | 0 | 0 | 0 | 0 | 0 |
| Region of Enrollment(participants) | DTX401 Cohort 1 | DTX401 Cohort 2 | DTX401 Cohort 3 | DTX401 Cohort 4 | Total |
|---|---|---|---|---|---|
| Canada | 0 | 0 | 1 | 0 | 1 |
| Netherlands | 0 | 0 | 0 | 2 | 2 |
| United States | 3 | 3 | 2 | 0 | 0 |
| Spain | 0 | 0 | 0 | 1 | 1 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No — Due to the rarity of GSDIa and the small number of subjects in this trial, individual patient data will not be shared in order to safeguard patient privacy, consistent with the data sharing commitment statement listed on Ultragenyx.com.
Ran from Jul 2019 to primary completion in Feb 2025, 67 months.
Results were first posted in Mar 2026, 1 year after primary completion.
Of 23 observational studies under Glucose Metabolism Disorders, half reached primary completion within 31 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 67. This study's 67 months is above that.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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