Diagnosis-led treatment
Gene-targeted treatments
Antisense oligonucleotides, gene replacement, enzyme replacement, targeted small molecules
The genuinely transformative development in paediatric neurology — and it is strictly conditional: these treatments work for named genetic diagnoses and do nothing at all without one.
Either a medicines regulator has licensed it for this use, or clinical practice guidelines recommend it on the strength of controlled trials. This is the standard everything else on the scale is measured against — and for most children, the treatments at this level are the ones that will actually change their day.
Where it stands, condition by condition
The same therapy can be well supported for one problem and completely untested for another. This is the single most common place families are misled.
| Condition | Evidence | What that means here |
|---|---|---|
| Spinal muscular atrophy | Established care | Several licensed treatments with different mechanisms: an intrathecal antisense oligonucleotide, a one-off AAV gene replacement, and an oral splicing modifier. This condition was reshaped within a decade. |
| CLN2 Batten disease | Established care | Enzyme replacement delivered into the brain's ventricles slows functional decline. |
| Metachromatic leukodystrophy | Established care | An ex vivo gene therapy using the child's own corrected stem cells, licensed in Europe for early stages, before symptoms are established. |
| AADC deficiency | Established care | A gene therapy delivered directly into the brain, licensed in Europe. |
| Duchenne muscular dystrophy | In clinical trials | Exon-skipping oligonucleotides and an AAV gene therapy are licensed in some jurisdictions under accelerated pathways; the size of the functional benefit remains debated. |
| Dravet syndrome, Angelman syndrome, other channelopathies | In clinical trials | Antisense approaches are in clinical trials. Not approved. This is where a registered trial is a reasonable thing to seek out. |
| Cerebral palsy from acquired injury | Not supported by evidence | There is no gene to target. Genetic treatments have no role where the cause is an injury rather than a gene. |
What it is
Four related but distinct strategies. Antisense oligonucleotides are short synthetic strands that change how a gene's message is read — they are usually given repeatedly, often into the spinal fluid. Gene replacement delivers a working copy of the gene in a viral vector, usually once. Enzyme replacement supplies the missing protein directly. Targeted small molecules are ordinary drugs chosen because of what the specific mutation does.
What they share is the requirement for a confirmed molecular diagnosis. There is no general-purpose version, and nothing here is given on the basis of a clinical label alone.
Timing is usually decisive. Most of these treatments protect neurons that are still alive; they do not restore what has already been lost.
How it is meant to work
Each targets the specific fault: restoring a missing protein, raising output from a healthy copy of the gene, or correcting the message itself.
This is why the benefit is so much larger than anything on the emerging therapies page, and why it is so much narrower. A treatment that fixes one gene does nothing for a different one.
It is also why newborn screening matters. In spinal muscular atrophy the difference between treating a newborn and treating a symptomatic infant is not incremental.
What has actually been tested
- Spinal muscular atrophy is the proof of principle. Within roughly a decade it went from a condition with no treatment to one with several licensed options and newborn screening in many countries.
- Several other licensed treatments exist for rare metabolic and neurodegenerative conditions, approved on the basis of slowed decline rather than reversal — which is the realistic standard here.
- For the large genetic epilepsies, antisense approaches are in trials. Being in a registered trial is a reasonable goal for a family in that position, and it is free.
- Note the pattern that runs through all of it: benefit depends on starting before damage accumulates. That argues for prompt diagnosis far more than for any particular product.
What we still do not know
- How durable one-off gene replacement is across a lifetime, and whether redosing will ever be possible given immune responses to the vector.
- Long-term safety in children treated in infancy — the oldest recipients are still young.
- Whether treatment started after symptoms are established alters the eventual outcome, as opposed to slowing the rate of loss.
- Cost and access, which for several of these are among the highest of any medicine in the world.
Risks and costs
- Serious and specific, which is appropriate for treatments with serious effects: liver injury and immune reactions with AAV gene therapy, requiring steroid cover and close monitoring; procedural risk with repeated intrathecal dosing; conditioning chemotherapy before ex vivo gene therapy.
- These are specialist-centre treatments with structured long-term follow-up, and should never be sought from a clinic offering them informally.
- The other risk is the mirror image: a child who never gets the diagnosis and therefore never gets considered.
Questions to ask before you agree
A centre that is doing good work will welcome these questions and answer them in writing.
- Does my child have a confirmed molecular diagnosis, and is there an approved or trial treatment for that exact gene?
- If there is, is there a time window, and are we inside it?
- Which centre delivers it, and what is the long-term monitoring plan?
- If there is no treatment for this gene yet, is there a registry or a trial we should be on?