Mucopolysaccharidosis type IIIB (Sanfilippo syndrome type B) OMIM 252920
In Mucopolysaccharidosis type IIIB (NAGLU, OMIM 252920), the master switch sits on the ↓ DOWN branch ([F] forced below); the healthy state is the ON well. The forced corrective direction is to raise s toward ON branch (polarity: supply). Classification: ○ Novel direction-only lead. Direction only — no dose, no efficacy magnitude.
The disease maps to an R19 double-well whose corrective lever is read straight off the cusp (barrier 0.5501, γ 1.4834, spinodal 0.6954). The corrective direction is forced [F]; the agent names below are direction-concordant labels at grade [O] (no dose, no efficacy or safety magnitude). This is a research hypothesis offered to experts, not medical advice.
The emergence switch
The switch for Mucopolysaccharidosis type IIIB is an R19 double-well emerged from the real proximal-promoter DNA of NAGLU. Its geometry is fixed by measured stiffness γ (never fitted); the numbers below are read directly off that cusp.
emergent axis
↓ DOWN [F]
healthy branch
ON
lesion
LOF_null
γ (stiffness)
1.4834
barrier
0.5501
spinodal
0.6954
s_on / s_off
1.2179 / -1.2179
fragility
0.22
corrective polarity
supply
forced direction
raise s toward ON branch
Chemistry feasibility (DIRECTION only [O]). small-molecule recrossing of the fold is geometrically harder (barrier 0.5501 at neutral drive; lower barrier = smaller drive to supply). [O] -- no affinity/potency/dose/efficacy asserted.
The derived corrective lever
The cusp forces a corrective direction: raise s toward ON branch. This is the load-bearing output of the framework — it is [F] forced, and it is falsifiable. 2 lever families are derived; the lead is h-restore (drive modulator).
Mechanism. supply / restore the positive drive (replace-or-agonise the missing competence)
Applies to. allele-agnostic (downstream/environmental tilt)
favoured when the switch is fragile -- a small drive shift recrosses the fold
Falsifier. If supplying/agonising NAGLU (raising the switch drive) does NOT move the DOWN [F] switch toward the healthy branch in a NAGLU-deficient model, the h-restore(supply) lever is refuted for this axis.
Falsifier. If a folding-stabiliser/chaperone does NOT re-deepen the healthy well for a residual NAGLU allele (no rescue that a null allele lacks), the gamma-restore lever is refuted; null alleles are excluded by construction.
Agents mapped onto the lever
Existing agents whose known action is direction-concordant with the derived lever (status as pinned in the corpus; no dose, no efficacy magnitude).
agent (class)
dir.
status
phase
map
IGF2-fused recombinant human NAGLU ICV enzyme replacement (tralesinidase alfa / TA-ERT, Spruce Biosciences) -- DIRECT on the causal NAGLU function; FDA Breakthrough Therapy Designation 2025-10, BLA Q1 2026; as of June 2026 NOT approved
Spruce Biosciences TA-ERT FDA BTD 2025-10; Sanfilippo natural history
increase
clinical
3
◇ in trials
AAV9-NAGLU in vivo gene therapy (ABO-101 / SNG-101, a BBB-crossing one-time IV infusion) -- DIRECT on the causal NAGLU gene; clinical-stage, as of June 2026 NOT approved
⚠ Mechanism-direction only — do not self-administer; no dose (unvalidated; set by a physician / national authority); not an approved use.
Direction-only candidate leads (corpus join)
Each lead is surfaced only because its known mechanism points the same way as the derived lever, and each comes with a source and a falsifier. None is a treatment.
Mechanism. An investigational fusion enzyme replacement delivered intracerebroventricularly to supply alpha-N-acetylglucosaminidase (NAGLU) and clear heparan-sulfate accumulation in the CNS (the fusion improves cellular uptake/CNS distribution). Direction on the disease axis: increase -- supply the deficient lysosomal enzyme. Engaged node: NAGLU (unique among the 113). Allele scope: agnostic. Addresses the honest-miss reason (no approved CNS-crossing enzyme replacement; standard intravenous enzyme does not cross into the CNS). INVESTIGATIONAL direction-only hypothesis (no efficacy/approval/availability claim); status per training knowledge to Jan 2026 -- confirm current development.
Prior-art. Direction-only hypothesis: the geometry derives an increase (supply the deficient enzyme) for NAGLU; the investigational intracerebroventricular NAGLU fusion enzyme replacement tralesinidase alfa supplies alpha-N-acetylglucosaminidase directly to the CNS, a matched increase, addressing the honest-miss reason (intravenous enzyme does not cross into the CNS). Investigational; confirm current status. No efficacy/availability claim.
Safety (qualitative; no magnitude). investigational intracerebroventricular enzyme replacement; device-delivery and infusion considerations (qualitative; no magnitude); confirm current development status
Falsifier. If tralesinidase alfa (a gene-specific supply/increase agent) does NOT move the DOWN [F] switch toward the healthy branch in a NAGLU-deficient model, the h-restore(supply) direction is refuted for tralesinidase alfa here.
Source: Tralesinidase alfa investigational intracerebroventricular NAGLU enzyme-replacement programme in MPS-IIIB
⚠ Mechanism-direction only — do not self-administer; no dose (unvalidated; set by a physician / national authority); not an approved use.
Evidence & provenance
What is reproduced vs. cited for this page.
element
grade
basis
R19 switch & cusp geometry (this page)
[V] verified
emerged from measured promoter γ of NAGLU; deterministic, 2×sha256 identical
corrective direction
[F] forced
forced by the cusp sign; falsifiable (see lever falsifiers)
mapped agents / leads
[O] open
direction-concordance only; corpus-pinned (2026-06-21); no dose, no efficacy/safety magnitude
Reading the agent column. VALIDATION SIGNAL -- the agent is already approved / established standard for this disease, so the direction logic recovered known clinical practice. Not a new claim by this kit. GENUINE HYPOTHESIS -- no approved indication for this disease; the direction match is a direction-only, untested [O] lead. Basis field grades the evidence (investigational here / in a related condition / off-label / speculative).