Chapter Four · SYNGAP1-related disorder
Years of appointments, a diagnosis of “developmental delay” which is a description rather than a cause, and no name for what is happening.
Start with a phone call. Your doctor’s office has a triage line and a nurse will talk it through with you. They are good at this, they do it all day, and it costs nothing. You ring the main number and ask for the triage nurse. There is no charge and you do not need an appointment.
If it feels more serious than that, go to urgent care. You will usually be seen faster than at a hospital.
If it feels life-threatening — chest pain, trouble breathing, confusion, no urine at all for a day — call 911 or go to the emergency room. Do not wait until you are sure. Take the more cautious road.
Rather listen?
Takes about 7 minutes, read aloud. It is the same words as the page below, so nothing is missing if you would rather read. Download it to keep on your phone — it will play with no signal, in a waiting room or a car.
A single gene, and a test that finds it. SYNGAP1-related disorder is caused by a
change in one gene. It is found by genetic testing — and it is not found at all
unless somebody orders that test.
→ where this is explained: What it is
Most of the people who have it do not know. The gap between how many are thought
to be affected and how many have been identified is very large.
→ where this is explained: Why it goes unfound
“Autism with epilepsy” is a description, not a cause. Where both are
present together, a genetic cause is worth asking about.
→ where this is explained: What it gets taken for
Tick the ones that apply. The bar below shows how much they add up to.
What we would do, as a friend rather than as your doctor. This is our opinion and we stand behind it. It is not medical advice and we are not examining you.
It is not a one-time reading. If you start feeling worse while you are deciding, move up a level. Nobody has ever been criticised for turning up and being sent home. A false alarm is the best possible outcome here.
If none of these apply, the rest of this chapter is worth your time. Take it slowly; there is no clock on it.
A gene called SYNGAP1 carries the instructions for a protein used at the junctions between brain cells. Where one copy of that gene is altered so it makes too little of the protein, those junctions do not settle the way they normally would. The result is a combination that tends to travel together: delay in development, difficulty with learning, seizures, and autistic features.
It is present from birth. It is not caused by anything a parent did or did not do.
Because nothing about the child says “order a genetic test” unless somebody is thinking of one. The delay is visible, the seizures are visible, and both can be managed as findings in their own right for years without the question of a single underlying cause ever being put.
Grade C The source this chapter was built from records that this is among the more common single-gene causes of intellectual disability, and that the number of people identified is a small fraction of the number thought to be affected. Those figures are carried from that document and have not been re-checked against the primary literature for this page. They are here because the shape of the claim — many affected, few found — is the point, and the shape does not depend on the exact number. Treat the numbers themselves as needing confirmation.
Autism, on its own. The features overlap. The distinguishing question is whether epilepsy is also present, and whether anyone has looked for a single cause behind both.
“Global developmental delay”. A true description of what is happening and not an explanation of why, in exactly the way that chronic kidney disease is in Chapter One.
Epilepsy of unknown cause. Where seizures and developmental difficulty occur in the same child, a genetic cause is a reasonable thing to ask about.
The test is genetic. Ask specifically whether an epilepsy gene panel or exome sequencing has been done — a panel looks at a defined list of genes, and exome sequencing looks much more widely. Which is appropriate is a clinical decision, but whether either has been done is a question anyone can ask.
A result changes practical things: which seizure medicines are more likely to suit, what to watch for, and access to a community of families and to research that is specifically about this condition rather than about delay in general.
“Has my child had genetic testing? If so, which test — a panel, or exome sequencing?”
“My child has both developmental delay and seizures. Has a single underlying cause been looked for, rather than treating the two separately?”
“If the first test was normal, was it a panel? Would a broader test find something a panel would not?”
“If a cause were found, would it change which medicines we try?”
Next chapter: Itching and skin changes nobody has looked at properly
Built from SYNGAP1-Disease-Room.html, 4 May 2026, recovered
from the archive on 8 September 2026 and rewritten for this site. Figures marked Grade C
are carried from that document and have not been re-verified here. Nothing on this page
comes from any individual’s medical record.