One letter in one gene, and an honest account of what is known about it.
If you have just been given this variant name and you are frightened, start here. This page says what has been measured, what has not, and where the uncertainty actually sits.
What Brugada syndrome is
It is a condition of the heart's electrical system rather than its structure. The heart beats because an electrical signal sweeps through it in a coordinated wave. In Brugada syndrome that signal can be weaker or slower than it should be in one part of the heart, and under certain conditions the rhythm can become dangerously disorganised.
Because the problem is electrical, the heart usually looks entirely normal on a scan. A normal echocardiogram does not rule it out, which is a common and reasonable source of confusion. It is diagnosed from a particular pattern on an electrocardiogram, sometimes only visible during a fever or after a specific medication.
Fever is a recognised trigger.
That is worth knowing, and worth mentioning to any doctor treating you for an illness. What to do about it is a conversation with your own doctor, not something this site can answer. Most people who carry a variant associated with this condition never develop symptoms.
What is known, and what is only believed
What the name means
SCN5A is a gene. It carries the instructions for building the sodium channel that starts the electrical signal for each heartbeat. Think of the channel as a gate in the surface of a heart cell that opens to let each beat begin.
A gene is written as a long sequence of chemical letters, and this variant changes one of them. c.311G>A means that at position 311 the letter G was replaced by an A. That single change alters one building block in the finished protein, which is what p.Arg104Gln records: at position 104, arginine was replaced by glutamine. Arginine is abbreviated R and glutamine is abbreviated Q, which is where R104Q comes from. All four names refer to the same single change, and you may see any of them on a laboratory report.
About risk
Most people who carry a variant like this one never have symptoms. Whether that is true for any particular person depends on far more than the variant, and it is a judgement for an electrophysiologist who has the whole picture: the rest of the genome, the medical history, the family history, and an examination. A website cannot make that judgement and this one will not try. If you are looking for what to ask at your next appointment, that is on the page for carriers.
The papers
There are ten, and seven of them report a negative result, meaning the finding went against the idea being tested. One of those closed a route this project had spent months on, and another found that a method I had been relying on missed three of the four cases it should have caught. All ten carry a permanent identifier, and the data they rest on is a single archive under one more. Read all ten, each with a one line plain summary.
Who wrote this
I am Ethan Bradley. I carry this variant. I am not a physician and nothing here is medical advice. The work is computational, which means it is done with databases, published measurements and simulations rather than at a laboratory bench, and it nominates experiments rather than performing them. I publish the reasoning so that anyone can check it, and I publish the results that went against me alongside the ones that did not.
My own variant is why I went looking, but most of what came out of it is not about me. Two variants in this same small region of the gene carry strong laboratory evidence of harm and have never been reported in a patient. Those belong to people who do not know yet.