Just found out about possible genetic condition at 34 weeks... scared

[CobaltRose96]

Hi all.

I'm currently 34 weeks pregnant with my first child. All scans and tests have been normal and the combined screening came back low risk.

My partner's father remarried after separating from his mum and has since had another child with his new wife. My partner's half sister is now 6 years old and was initially thought to be severely autistic. However, genetic testing has recently come back to reveal that she has a condition called chromosome 16p11.2 deletion. Further genetic testing on her parents revealed that my partner's father also has it, although he is much less severely affected. He has some mild autistic traits but they only really become apparent if you know him. His daughter however is severely affected (severe and numerous developmental delays).

I know absolutely nothing about this condition and what the chances may be of our child inheriting it. Neither my partner nor his three brothers appear to have inherited it (although they haven't been tested) and I myself have no family history of genetic conditions.

Again, all of our scans and tests have shown that our baby girl appears to be perfectly healthy, and from what I've read and what my partner's stepmother has told us, some of the features of of this condition are often apparent on scans.

Of course we will love and treasure our daughter regardless (I've previously had a traumatic miscarriage), but it is scary to suddenly find out that there is a family history of a genetic condition.

I don't know where to go from here. I'm already 34 weeks pregnant so she'll be here before long. Is it worth mentioning this to my midwife at my next appointment?

Sorry if I sound like I'm rambling, we only just recently found this out and I'm still reeling somewhat. Any advice would be appreciated!

Thank you

This must be very worrying for you. This is my best guess on the situation. Your father in law has two copies of chromosome 16. One of these has the deletion. His children will have each inherited only one of his two copies of chromosome 16 - i.e either the one with the deletion, or the normal one. Your SIL unfortunately inherited the one with the deletion. If your husband has no symptoms then it seems likely that he inherited the normal chromosome 16. Therefore your husband does not carry the chromosome 16 with the deletion (he has one normal one from his father, and one normal one from his mother), and so he cannot pass it on to your baby. I hope that is helpful.

Have you read this - ghr.nlm.nih.gov/condition/16p112-deletion-syndrome#resources ?
As it is a dominant autosomal disorder if your husband doesn’t have it, your baby cannot inherit it. Your husband had a 50% chance of inheriting it from his dad so he most likely didn’t.
Because they say that the symptoms vary a lot between sufferers, even assuming your husband does have it, if it doesn’t run in your family then your baby only has a 50% chance of having it. But I doubt there would be no symptoms at all in your husband if he was a sufferer.
Mention it to your midwife but I would take comfort in the fact your husband doesn’t have any symptoms as that strongly indicates he doesn’t carry the disorder.

@shineyshoes10 the deletion is not on the sex chromosomes, it’s on chromosome 16.

Thank you all. I have a routine midwife appointment on Thursday anyway so will mention it to her then. My partner hasn't been sent for any testing as he doesn't show any signs of the condition himself.

Part of me sees little point in testing, as if she does indeed have it there is nothing we can do about it, and we will love her regardless! But another part of me wants the testing to give myself peace of mind OR time to prepare (whichever it may be). My partner's sister is a lovely little girl but her behaviour is indeed very challenging at times. She is only just learning to talk now at six years old, and as a result of her difficulties with communication she can become frustrated and very aggressive at times. It isn't her fault at all and she's a sweet, loving child at other times, but I can see that it is incredibly difficult for her parents to cope with at times (especially her dad who has difficulties of his own).

Whatever the outcome, our little girl is very much wanted and adored anyway.

If your husband doesn’t show any symptoms I really don’t think there’s a risk.

Hello! I dont suppose you have an update?
I'm pregnant with my 2nd child and my husband's nephew has just been diagnosed with 16p11.2 deletion syndrome at the age of 16 months. Not sure whether I should ask for testing to be done during this pregnancy. Would love to know you thoughts x

@Bluebeeinthewoods the genetic clinic should arrange for you to have testing asap if it’s applicable in your case. Ask your husband’s sibling to tell Genetics that you are pregnant and they should react quite quickly. (We’ve just had a very similar situ with an unrelated gene)