Rare Chromosomal abnormality found during amnio

[hattie]

Because of my age and a slightly high risk of down's on the screening tests, I had an amnio.  The amnio came back negative for all the things we were worried about, but positive for Mosaic Isochromosome 20q.  Which means that some of the cells evaluated during the amnio were normal but some had abnormalities in chromosome 20.  There are only 25 reported cases and only about 4-5 research papers discussing the abnormality, and absolutely no conclusive evidence about what it really means.  Of the 25 reported cases, 21 resulted in babies with no complications at all (although the longest study only studied the kids up to age 3 1/2, so there is very little long-term data).  But the 4 other cases resulted in the babies having complications that weren't compatible with life.  Researchers suspect that in the 21 cases, the abnormal cells weren't even in the baby, but instead were "other embryonic" cells (cells from the placenta instead of the fetus, for example) that get picked up during an amnio.  And in the 4 cases with very bad outcomes, there was no consistency amongst the problems.  Each of the 4 babies had some different but very serious complication, which means that they can't even say that this particular abnormality caused any of those babies' problems.  It might have just been a coincidence and those babies would have had those complications even without the abnormal chromosome. 

So I have all this really scary information about something that might not mean anything at all and I'm not sure what to do with it.  The geneticist did an ultrasound at 18 weeks and everything looked completely fine and we're doing another ultrasound at 22 weeks to check again.  Of the 4 cases with bad outcomes, those moms actually got amnios because the problem showed up first on a routine ultrasound.  So the fact that our ultrasounds look good is definitely reassuring.  So far, everything we know points towards everything being fine, but it's not easy to put the worry out of my mind.

I guess I wonder if anyone else knows anything about Mosaic Isochromosome 20q?  But I suspect not since it's so rare.  Maybe I just needed to write this down and send it out.  It's hard to have no control over something so important.    

[SoCaliMommy]

 You might want to post this in the special needs forum  to get more responses. 

[noahs.mom06]

Another potential resource for more information is the website www.benotafraid.net

[kriket]

Did you speak to the genetic counselor? They are supposed to help you understand these things when they drop this kind of news on you. From what I have read about this (I am interested in genetics :) My aunt had an unidentified genetic condition, and they intrigue me) anyway, from what I read, you are correct, of the few cases they have identified, the majority the baby showed zero signs of outward, or genetic problems. There were a small minority that had difficulties, however, even after more study and research, the Drs couldn't say what or why they had the complications.

Much love :) I know you will worry, but please don't! The odds of a perfectly healthy baby are still in your favor!

[Kokopelli-mana]

Stay positive. So many amnio and cvs results cause unnecessary anguish and heartache to pg mothers. Since the abnormality isn't linked specifically to any disorder, it is likely your baby is perfectly normal. Good luck to you

[MissDelta]

I faced the same situation 15 years ago during my pregnancy.  I was offered genetic counseling and I declined it.  I didn't want to think about anything "bad' for the rest of my pregnancy.  I knew I could not handle the stress of worrying about my baby.  I simply "forgot" about it. I am the mother of a healthy and  wonderful 14 year old daughter with an attitude.  Since there are so few cases of this,  I have always told my daughter that this chromosomal abnormality makes her a one in a million person.  It was only after I started goggling mosaic isochromosome 20q that I realized that I faced some serious issues.  All I can only say that ignorance was best for me during my pregnancy.  Good Luck to you.   FYI   I was 40 when I had my daughter.

[Bird Girl]

One fact about mosaicism in any chromosomal abnormality is that because the abnormality is found only in some cells, not all cells, the kinds of disabilities that might occur will be unique to that individual. It's really a case of no one being able to tell ahead of time what a prognosis or outcome might be, because the case is totally unique. I hope you can get more helpful information--there's nothing like worrying about your baby when you are pregnant. It seems like your odds could be very good for a healthy outcome.

[Jane]

We know that placentas are ripe with errors in the genome.  They are meant to be a disposible organ, and it shows - they seem to be assembed rather sloppily, compared to the care that goes into the baby. I hope that the mosiacism they found is strictly present in some parts of the placenta and your baby is just fine.  Do you like your genetic counselor?  It would be nice to check in him/her every so often, just because more questions come up over time.  Or perhaps they could recommend someone else.  I'd expect you to be fine for a bit, then overwhelmed, then fine (much like any pregnant person, really).  It's nice to have pre-planned check in times so you don't have to call when you're feeling unsettled. 

[hattie]

Thank you all for these replies; they've honestly been incredibly helpful and encouraging.  I really, really appreciate it.  Especially MissDelta.  I know that one person's experience has no direct correlation to mine, but every positive outcome that I hear about brings me huge relief.  And Jane's point about the placenta makes so much sense - thank you!  We had perfect ultrasounds at 18, 22, and 26 weeks (I'm at 31 weeks now).  The cases with bad outcomes that have been reported all had something visible on an ultrasound by week 20, so the odds of the abnormality being in the placenta and not the baby look pretty good.  I get a little less nervous with each ultrasound, which makes it tempting to keep doing monthly ultrasounds.  But I've decided to wait and just do one more at the very end of the pregnancy, around week 37.  At this point, the ultrasounds only serve to reassure me.  If anything comes up from here on out, it's too late to do anything prenatally to try and fix/mitigate it.  But it would also be good to know in advance, to the extent we can, whether we'll need extra help at delivery, which is why we're doing the week 37 ultrasound.

Thank you guys, so much.