An estimated 5,000-10,000 Americans live with Pompe disease. Roughly 2,000 late-onset patients are on enzyme replacement therapy, and one in four is not responding well enough to it.
Pompe disease is a rare, progressive lysosomal storage disorder caused by acid alpha-glucosidase (GAA) deficiency, and the US patient population is estimated at 5,000 to 10,000 across both subtypes. Late-onset Pompe disease (LOPD) accounts for 70 to 80 percent of that population, presenting in adolescence or adulthood with progressive proximal myopathy and respiratory decline; infantile-onset Pompe disease (IOPD) makes up the remaining 20 to 30 percent and presents in infancy with severe hypertrophic cardiomyopathy. Of the LOPD population, roughly 2,000 patients are currently on enzyme replacement therapy (ERT), the funnel's clearest treated-population anchor point.
Within that treated cohort, response is not uniform. An estimated 25 to 30 percent of the roughly 2,000 US LOPD patients on ERT, 375 to 600 patients, are inadequate responders: forced vital capacity declining 5 percent or more per year, or 6-minute-walk-test performance declining 10 percent or more over 12 months, despite 12 or more months of treatment. That segment is the addressable population for next-generation ERT switching, and it is a materially larger commercial opportunity than the newly diagnosed pool alone. One gap this model flags rather than papers over: no publicly reported figure separates a newborn-screening detection rate or a total-diagnosed count from the treated population cited here, so the funnel below moves directly from total prevalence to treatment share; closing that diagnostic gap is a priority for the model's next update.
US Pompe disease funnel — from total prevalence to the switch-eligible inadequate-responder pool
| Funnel Stage | Population | Source |
|---|---|---|
| Total US Pompe disease patients (all subtypes) | 5,000-10,000 | AMDA/NORD |
| Late-onset (LOPD) share of total | 70-80% | AMDA/NORD |
| LOPD patients on enzyme replacement therapy | ~2,000 | US Pompe disease registry |
| Inadequate responders among ERT-treated LOPD | 375-600 (25-30%) | COMET & PROPEL ADA sub-analyses |
Sources: AMDA/NORD Pompe disease prevalence and subtype-share estimates; US Pompe disease patient registry treated-population figures; COMET and PROPEL trial anti-drug-antibody sub-analyses.
What this model answers
Every section answers a named commercial question your team is asking, scoped to your asset.
Delivers
- Total US prevalence (5,000-10,000)
- the 70-80% LOPD share
- the ~2,000 LOPD patients currently on ERT and where that sits within total prevalence
Delivers
- 375-600 (25-30%) inadequate responders among ERT-treated LOPD patients
- the FVC- and 6MWT-decline criteria that define inadequate response
- the next-gen ERT switching opportunity this segment represents
Delivers
- 8-sheet structure
- formulas throughout, zero hardcoded cells
- an explicit flag on the newborn-screening detection-rate gap this model does not yet close
Custom model delivered in 72 hours.
Commission This ModelWhat's inside
- Why the ERT-treated LOPD population, not total prevalence, sets the addressable pool
- Where the diagnostic-funnel gap (no NBS detection rate) limits precision, flagged not papered over
- 5,000-10,000 total US Pompe patients (AMDA/NORD)
- LOPD/IOPD subtype split (70-80% / 20-30%)
- 70-80% LOPD share driving the addressable population
- Diagnostic delay and the limb-girdle-muscular-dystrophy misdiagnosis pattern
- ~2,000 US LOPD patients on enzyme replacement therapy
- Where the treated population sits within total prevalence
- 375-600 (25-30%) inadequate responders on ERT
- COMET/PROPEL ADA sub-analysis criteria for inadequate response
- Which assumptions move the eligible pool most
- Scenario ranges across the prevalence and response-rate inputs
- Patient volume by horizon under conservative, base, and aggressive scenarios
- Revenue translation inputs
- The open questions your forecasting team must close before the model is finalised
- Structured for an internal forecast-review session
Included with every brief
How AXLRx builds this model
Prepared by MoatRx analysts.
Every AXLRx patient flow model is built on a five-layer funnel: population, disease burden (E1), diagnosis and subtype capture (E2), treatment and eligibility (E3), market access (E4), then Year 1-3-5 projections across three scenarios. Delivered as a live Excel workbook, not a static table: 8 sheets, formulas throughout, zero hardcoded cells.
US Pompe disease sources: AMDA/NORD prevalence and subtype-share estimates, the US Pompe disease registry treated-population figures, and COMET/PROPEL trial anti-drug-antibody sub-analyses for the inadequate-responder segment. Newborn-screening detection-rate and total-diagnosed figures distinct from the treated population are not yet available in a form this model can cite; that gap is flagged for the next update rather than estimated.
- US total Pompe disease prevalence estimate verified against AMDA/NORD published figures
- LOPD share of total population (70-80%) verified against AMDA/NORD
- On-ERT LOPD population (~2,000) verified against US Pompe disease registry figures
- Inadequate-responder share (25-30%, 375-600 patients) verified against COMET and PROPEL trial ADA sub-analyses
Frequently asked questions
Commission this model
AXLRx delivers rare disease patient flow models built for forecasting and launch teams sizing the US Pompe disease opportunity. Custom model in 72 hours.
Specify your indication, market, and cohort definition.
AXLRx analyst confirms funnel scope and comparator set before building.
Research-verified patient flow model in 72 hours with optional analyst readout.