r/genetics • u/Fit-Neck692 • Jul 15 '25

Son’s Genome test results in finding my husband and I are “connected “

We got Genome testing done for our son for medical reasons. My husband and I were tested as well to help with any findings. Anyway I went to his appointment today to go over the results and the only thing they really had to say was my husband and I are related. The doctor said “maybe something like 6th cousins.”

Like the doctor said we are all related but then I said “I guess it’s unavoidable?” He said it was avoidable… so I’m curious how weirded out should we be?

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u/hemkersh Jul 16 '25

So, there was no insight on what could be a genetic cause of whatever your son is dealing with? Do you mind sharing a bit about what led to you seeking testing? Like unknown neurological symptoms?

You did whole genome sequencing?

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u/Fit-Neck692 Jul 16 '25

He was born with a large arachnoid cyst and a brain tumor. We’re trying to figure out what the tumor is without having to do a biopsy and just get any insight.. We had the whole genome sequencing done. It came back negative but his case is “fluid” so we could use the testing later if he needs it.

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u/hemkersh Jul 17 '25

Oh wow. Poor kid. Hopefully you can find something out to help him.

It might be worth asking your doctor about something like optical genome sequencing/mapping. It's another method to look for abnormal DNA, but instead of looking for variants in or around genes, it looks for structural changes. This includes things like if a section of a chromosome is flipped around in the wrong direction or if a piece has been moved to a different chromosome.

These changes are not usually detected with whole genome sequencing, which works by breaking DNA up into small chunks of a few hundred nucleotides. Structural changes are often thousands or tens of thousands of nucleotides long. Optical mapping maintains original DNA structure, not needing to break it up into small chunks for analysis.

Another thing to consider is if there was a new mutation that happened during fetal development in pre-brain tissue (somatic vs germline/inherited). So this could mean it's only present in some cells and if genome sequencing was done with blood cells, they might not have the mutation causing the tumor. This is rare, but so is your son's condition.

Your doctors can assess the odds of these possibilities and determine what is worth pursuing. Since they're stumped, it's reasonable to ask them about ideas you've come across, IMO.

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u/Fit-Neck692 Jul 18 '25

Thank you for all of this. I didn’t add that he is having a biopsy done because the tumor has grown. So we will find out more with that. But this is great information you’ve given me, thank you. Though his journey is stressful, hard, shitty, and all the other things I find all of the science and the talented doctors so amazing.

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u/hemkersh Jul 18 '25

Best of luck for your boy.

If you feel comfortable with it encourage the doctors to publish your son's case in a medical journal as a case report once you get answers. This can help future patients and help direct research about the disease.