Key takeaways
- 700-900 Diagnosed UK Fabry patients across six NHS lysosomal storage disorder specialist centres
- 600/200 Approximate ERT-to-oral treated-population split (agalsidase beta vs migalastat)
- 50-80 UK ADA-positive patients with inadequate ERT response, the pegunigalsidase alfa TA915 target niche
- 80-120 Estimated undertreated symptomatic UK female Fabry heterozygotes, despite existing NHS clinical-policy eligibility
The UK's 700-900 diagnosed Fabry population is the best-characterised in Europe, and its two internal niches, ADA-positive responders and undertreated female heterozygotes, are sized from named NHS registry and clinical-service sources rather than epidemiological inference.
An estimated 700-900 UK Fabry patients are diagnosed and managed through six NHS lysosomal storage disorder specialist centres, with roughly 600 of those tracked in the UK Fabry Outcome Survey longitudinal registry. The treated population splits cleanly by mechanism: approximately 600 patients on agalsidase beta enzyme replacement, commissioned via NHS clinical policy, and approximately 200 on oral migalastat under NICE's HST4 recommendation, a roughly 75/25 ERT-to-oral split that reflects the UK's above-average migalastat uptake. Combined, that base population anchors an estimated £144 million annual NHS Fabry spend, one of the largest single lysosomal storage disorder budgets the NHS carries.
Two smaller, well-defined niches sit inside that base, each sized from a named source rather than a population-level estimate. The first is the ADA-positive cohort: 50-80 UK patients on agalsidase beta develop high-titre neutralising antibodies and show a faster eGFR decline, three to four mL/min per year against 1.5 to 2 in ADA-negative patients, despite ongoing ERT, the specific subgroup pegunigalsidase alfa's NICE TA915 recommendation now serves. The second is female heterozygote undertreatment: 300-400 of the 700-900 total NHS Fabry patients are female, and an estimated 80-120 of them remain symptomatic but undertreated because their presentation is classified as asymptomatic despite unrecognised early cardiac, renal, or neurological disease, a population identifiable under NHS clinical-policy criteria that already exist but are not being applied.
UK Fabry sizing — the base population and its two internal niches
| Sizing Gate | Population Estimate | Source |
|---|---|---|
| Diagnosed base population | 700-900 patients across 6 NHS LSD centres | UK Fabry Outcome Survey; NHS England LSD service specification |
| ERT vs oral split | ~600 agalsidase beta / ~200 migalastat | NHS clinical commissioning policy; NICE HST4 uptake data |
| ADA-positive suboptimal-responder niche | 50-80 patients | Royal Free London longitudinal cohort; BALANCE trial ADA sub-analysis |
| Undertreated symptomatic female heterozygotes | 80-120 of 300-400 total female patients | Royal Free London National Fabry Service census |
Sources: UK Fabry Outcome Survey 2023; NHS England lysosomal storage disorder service specification; NHS clinical commissioning policy (agalsidase beta); NICE HST4 evidence summary (migalastat); NICE TA915 final guidance (pegunigalsidase alfa, 2023); Royal Free London National Fabry Service census and outcomes data.
What this model answers
Every section answers a named commercial question your team is asking, scoped to your asset.
- How does the UK's 700-900 diagnosed Fabry population split between ERT and oral migalastat, and how does that base anchor the £144M NHS spend figure? • UK FOS registry cohort sizing methodology • the ~600/200 ERT-to-oral split • the £144M combined NHS budget derivation
- How large is the ADA-positive suboptimal-responder niche, and what clinical criteria define it? • The 50-80 patient ADA-positive cohort sizing • eGFR-decline benchmarking (3-4 vs 1.5-2 mL/min/year) • the TA915 label criteria this cohort must meet
- Why do 80-120 symptomatic female Fabry heterozygotes remain undertreated despite existing NHS eligibility criteria, and how is that population identified? • Female heterozygote symptomatic-undertreatment identification methodology • the asymptomatic misclassification pattern • the sizing basis for this second niche relative to the 300-400 total female NHS patient population
What's inside
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1 · The Binding Constraint 2 pp
- Why the two internal niches, not the 700-900 base total, are where a new entrant's sizing work has to focus
- Pressure-tested against UK FOS registry and Royal Free London census data before the rest of the model is built out
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2 · Registry-Based Sizing 3 pp
- UK Fabry Outcome Survey cohort (~600 patients) and NHS lysosomal storage disorder centre network coverage
- The 700-900 total diagnosed population and its ERT/oral split
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3 · ADA-Positive Niche Sizing 3 pp
- 50-80 patient cohort definition and eGFR-decline benchmarking
- Cross-check against pegunigalsidase alfa's TA915 target population
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4 · Female Heterozygote Undertreatment Sizing 3 pp
- 80-120 symptomatic, undertreated women within the 300-400 total female NHS Fabry cohort
- The asymptomatic-misclassification pattern driving underidentification
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5 · Triangulation & Confidence Range 3 pp
- Where UK FOS registry data, NHS commissioning figures, and Royal Free London census data agree and diverge
- £144M combined NHS spend as the budget-impact anchor
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6 · Editable Excel Model —
- The full triangulated model, re-runnable with your own assumptions
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7 · Client Alignment Questions 2 pp
- The open sizing questions your team must close before the number is used in planning
Appendix and source ledger included · 45-minute analyst readout included with delivery
Custom model delivered in 72 hours.
Assess this reportIncluded with every brief
Get Started
Commission this model
AXLRx delivers rare disease market sizing models built for forecasting and strategy teams sizing the UK Fabry opportunity. Custom model in 72 hours.
- 1. Submit your requestSpecify your indication, market, and cohort definition.
- 2. Scoping callAXLRx analyst confirms triangulation methods and comparator set before building.
- 3. DeliveryResearch-verified sizing model in 72 hours with optional analyst readout.
How AXLRx builds this model
Prepared by MoatRx analysts on the AXLRx commercial consulting engine.
Every AXLRx market sizing model triangulates at least two independent methods, registry-based and clinical-service census data, before accepting a patient count. This is explicitly a sizing model (static patient count), distinct from a Patient Flow or forecasting model.
UK Fabry sizing sources: UK Fabry Outcome Survey 2023, NHS England lysosomal storage disorder service specification, NHS clinical commissioning policy, NICE HST4 and TA915 documentation, and Royal Free London National Fabry Service census data.
- Diagnosed base population and ERT/oral split verified against UK Fabry Outcome Survey 2023 and NHS clinical commissioning policy
- ADA-positive niche sizing verified against Royal Free London's longitudinal cohort and the BALANCE trial ADA sub-analysis cited in NICE TA915
- Female heterozygote undertreatment estimate verified against Royal Free London National Fabry Service census data
Frequently asked questions
Deliverables What formats are included with every model?
Every commissioned Market Sizing Model includes an editable 5-sheet Excel model (Cover, Model, Research Validation, QC, Sensitivity) and a PDF methodology brief. There is no PowerPoint deck, since a sizing model is built to be worked in directly rather than presented from. An optional 45-minute analyst readout call is included.
Sources How is the patient count verified?
AXLRx triangulates every sizing estimate across at least two independent methods, registry-based and clinical-service census data. No single-source number ships unverified.
Customisation Can I size a specific niche or comparator cohort?
Yes. The intake form captures your indication, target niche, and cohort definition. A scoping call confirms scope before research starts. Commission via the intake form to start.