Genglycos (pariglasgene brecaparvovec)
An approved treatment for Glycogen Storage Disease Type Ia.
The same compound appears under different names depending on the context. Here is how to identify Pariglasgene brecaparvovec wherever you encounter it, plus the key facts at a glance.
- Generic name
- Pariglasgene brecaparvovec
- Brand name
- Genglycos
- Development code
- DTX401
- Drug class
- Gene therapy (AAV8 vector)
- Manufacturer
- Ultragenyx Pharmaceutical
- How it's taken
- A single intravenous infusion of 1.
A one-time gene therapy infusion for people 8 and older with glycogen storage disease type Ia, given accelerated approval on August 19, 2026 to reduce how much cornstarch they need each day alongside their nutrition plan.
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Where Pariglasgene brecaparvovec fits
The first gene therapy for GSD Ia, used on top of the standard nutrition plan of frequent meals and cornstarch, with the goal of needing less cornstarch day to day.
How Pariglasgene brecaparvovec works
In GSD Ia the liver lacks glucose-6-phosphatase, the enzyme that releases glucose into the blood between meals. Genglycos uses a harmless, non-replicating virus shell called AAV8 to carry a working copy of the G6PC gene into liver cells, where it stays mostly outside the cell's own DNA and lets the cells make the enzyme. Steroids are given afterward to calm the immune reaction to the virus shell, which can inflame the liver.
Mechanism: One-time AAV8 gene therapy that delivers a working copy of the G6PC gene to liver cells so they can make the glucose-6-phosphatase enzyme
Side effects and safety
- Allergic and infusion reactions. Anaphylaxis occurred within minutes of the infusion in 2 of 21 people in GlucoGene. People are watched closely during and after the infusion.
- Liver inflammation. Liver enzymes rose in 71% against 12% on placebo, mostly mild to moderate, peaking 4 to 12 weeks after the infusion. Liver tests are checked for the first 6 months, and steroids are given to every patient to limit it.
- Adrenal insufficiency from steroids. Occurred in 24% (5 of 21). Steroids are tapered slowly, never stopped suddenly, and people are watched for weakness, low blood pressure or low blood sugar during and after the taper.
- Theoretical tumor risk. Vector DNA could in theory join the cell's own DNA and raise tumor risk; any tumor after treatment is reported to Ultragenyx.
- A blood test for antibodies to AAV8 before treatment; people with detectable antibodies cannot receive it
- Liver history and liver tests before the infusion
- Liver enzymes for the first 6 months after the infusion
- Signs of adrenal insufficiency during and after the steroid taper
- Blood sugar, with the nutrition plan adjusted under the care team's direction
Genglycos has no boxed warning. It must not be given to people with severe liver scarring (fibrosis) or cirrhosis. In the GlucoGene trial, liver enzyme rises occurred in 71% of people on Genglycos against 12% on placebo, peaking 4 to 12 weeks after the infusion and resolving within 15 weeks; 2 of 21 people (10%) had anaphylaxis within minutes of the infusion. The required steroids caused adrenal insufficiency in 24%, along with acne, high blood sugar and a puffy, rounded face in some people. The label also notes a theoretical risk of tumors if the vector's DNA joins the cell's own DNA.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Pariglasgene brecaparvovec
A single intravenous infusion of 1.0 x 10^13 vector genomes per kg, given once in a specialist center. Two weeks later a steroid course starts (prednisone or equivalent, 1 mg/kg a day for people under 60 kg or 60 mg a day for 60 kg or more, for 4 weeks), then is tapered over at least 4 more weeks. Cornstarch and the nutrition plan continue and are reduced only under the care team's direction.
Availability and cost
Only available as the brand-name product.
Help paying for Genglycos
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
If you have commercial insurance, the Ultragenyx Copay Assistance program may cover your out-of-pocket costs for the Ultragenyx medicine and the cost of giving it. You must meet Ultragenyx criteria, and Ultragenyx can change or end the program at any time.
For: private insurance · source - Insurance and case manager help
A Gene Therapy Guide helps you understand insurance coverage, checks whether you qualify for financial help, helps arrange travel and connects you to resources. UltraCare says it can check eligibility for financial help no matter what insurance you have. Your doctor completes the enrollment form with you.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source
Good to know: The copay terms come from Ultragenyx's general UltraCare page, which covers all its products; no Genglycos-specific dollar cap is published. UltraCare also lists a travel support program for medically necessary gene therapy travel for the patient and up to 1 caregiver, for those who meet Ultragenyx criteria.
Access and eligibility
Approved for people 8 years and older with GSD Ia. Not for people with severe liver scarring or cirrhosis, and the label advises avoiding it with existing liver impairment or an active viral liver infection. People must have no detectable antibodies to AAV8. It does not replace the nutrition plan; cornstarch is reduced only as the care team directs.
Access program details are provided for informational purposes and may vary based on insurance coverage, geographic location, and individual circumstances. Confirm current eligibility directly with the manufacturer or your specialty pharmacy.
Clinical trial results
GlucoGene (NCT05139316), a Phase 3 randomized, double-blind, placebo-controlled trial, treated 46 people (21 on Genglycos, 25 on placebo) for 48 weeks. Daily cornstarch fell 41.1% on Genglycos against 10.2% on placebo, a difference of 30.9 percentage points, about 1.2 fewer cornstarch doses a day against 0.2. Among 15 people with 96 weeks of data, cornstarch was down 60.8%, an observation without a comparison group. The label notes slightly more continuous glucose readings below 70 mg/dL than on placebo (3.1 percentage points). The approval is accelerated, so continued approval may depend on a confirmatory trial.
Development history
Developed by Ultragenyx under the code DTX401. The FDA granted accelerated approval on August 19, 2026, making Genglycos the first approved treatment aimed at the cause of GSD Ia. DailyMed lists a marketing start date of September 17, 2026.
Explore Glycogen Storage Disease Type Ia trials
Common questions about Pariglasgene brecaparvovec
▸What is Pariglasgene brecaparvovec (Genglycos)?
A one-time gene therapy infusion for people 8 and older with glycogen storage disease type Ia, given accelerated approval on August 19, 2026 to reduce how much cornstarch they need each day alongside their nutrition plan.
▸How does Pariglasgene brecaparvovec work?
In GSD Ia the liver lacks glucose-6-phosphatase, the enzyme that releases glucose into the blood between meals. Genglycos uses a harmless, non-replicating virus shell called AAV8 to carry a working copy of the G6PC gene into liver cells, where it stays mostly outside the cell's own DNA and lets the cells make the enzyme. Steroids are given afterward to calm the immune reaction to the virus shell, which can inflame the liver.
▸What are the side effects of Pariglasgene brecaparvovec?
Genglycos has no boxed warning. It must not be given to people with severe liver scarring (fibrosis) or cirrhosis. In the GlucoGene trial, liver enzyme rises occurred in 71% of people on Genglycos against 12% on placebo, peaking 4 to 12 weeks after the infusion and resolving within 15 weeks; 2 of 21 people (10%) had anaphylaxis within minutes of the infusion. The required steroids caused adrenal insufficiency in 24%, along with acne, high blood sugar and a puffy, rounded face in some people. The label also notes a theoretical risk of tumors if the vector's DNA joins the cell's own DNA.
▸How is Pariglasgene brecaparvovec taken?
A single intravenous infusion of 1.0 x 10^13 vector genomes per kg, given once in a specialist center. Two weeks later a steroid course starts (prednisone or equivalent, 1 mg/kg a day for people under 60 kg or 60 mg a day for 60 kg or more, for 4 weeks), then is tapered over at least 4 more weeks. Cornstarch and the nutrition plan continue and are reduced only under the care team's direction.
▸Is Pariglasgene brecaparvovec FDA approved?
Yes, Pariglasgene brecaparvovec (Genglycos) is FDA approved (2026) for the treatment of Glycogen Storage Disease Type Ia.
▸Who can get Genglycos?
People 8 and older with glycogen storage disease type Ia who have no detectable antibodies to AAV8 and no severe liver scarring or cirrhosis. It is given once, by IV infusion, in a specialist center, followed by a steroid course.
▸Does Genglycos mean no more cornstarch?
Not for most people, based on the trial. In GlucoGene daily cornstarch fell 41.1% on Genglycos against 10.2% on placebo after 48 weeks. The approval is to reduce cornstarch as an add-on to the nutrition plan, and any change to cornstarch is made by the care team.
▸What are the main risks of Genglycos?
Liver inflammation (liver enzymes rose in 71% against 12% on placebo), allergic reactions including anaphylaxis during the infusion in 2 of 21 people, and side effects of the required steroids, including adrenal insufficiency in 24%. There is also a theoretical tumor risk from the gene vector.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed · 2026-09. GENGLYCOS (pariglasgene brecaparvovec-opnr): prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ef9144f5-10c3-47d9-a7c6-ab5ff11e9bf8
- Ultragenyx Pharmaceutical · 2026-08-19. Ultragenyx announces U.S. FDA approval of Genglycos gene therapy. https://ir.ultragenyx.com/news-releases/news-release-details/ultragenyx-announces-us-fda-approval-genglycostm-gene-therapy
- ClinicalTrials.gov. GlucoGene: DTX401 in glycogen storage disease type Ia. https://clinicaltrials.gov/study/NCT05139316