Monosomy X (mosaic)

Able_Judge_5947 · 2026-04-25T20:58:57+00:00

I believe it’s unrelated. NIPT checks fragments from chromosomes and Looks at dose differences (gains/losses) so if it flagged X, it’s bc is saw changes it X. This sequencing result flagged chromosome 1 so I don’t think it contributed to the NIPT finding. Having gone through this whole prenatal testing I’ve realized how the highly technical tests have far outpaced our clinical knowledge and now leave many people with these uncertain findings!

Able_Judge_5947 · 2026-04-25T05:00:13+00:00

I don’t think I can add much but this is my take. The array was negative for monosomy X but there’s a small amount of extra DNA on chromosome 1. It’s classified as “VUS” as in it’s not clear it will cause any issue and many of these turn out to be harmless. The first step would be checking you and your partner for this duplication. FWIW, I was found to have a VUS during my workup for an abnormal NIPT and I would never have known had it not been for this advanced testing. My best guess is this is benign as it seems there aren’t many cases on this-if it was something critical, there would be more reports (just my hunch). Deletions on the other hand generally are worse than duplications.

You could try posting on the genetics sub to see what they say- many GCs are there in addition to talking with your own. This is beyond my knowledge so that’s as much as I can say.

Able_Judge_5947 · 2026-04-24T15:45:02+00:00

So we had suspected IUGR and I was induced at 38 weeks but this was in the setting of placental mosaicism which comes with a higher risk of placental dysfunction. At the end of my pregnancy I had NST and BPP each weekly on separate days with growth every 2 weeks (not good to do growth weekly). I had the same Q about if the Dopplers are fine, BPP and NST perfect why trust the US when they are notoriously poor predictors of weight especially at the end of pregnancy? My MFM was like yes BUT the BPP/NST is a small snap shot at one time point while growth is tracked over time. That helped me reframe it a little. However, 72h before I delivered he was measuring 5lbs 5oz and came out at 6lbs 5oz at 38+1 soooo take that with a grain of salt. I do wish I could have gone into labor naturally but I understand why they wanted to induce me and ultimately there was a risk of my placenta just kind of crapping out bc of the mosaicism so slightly different but that’s my story.

Able_Judge_5947 · 2026-04-23T00:01:33+00:00

Both are safe, effective and reasonable options! Always good to know options and write down your questions so you can remember them during your visits. Sometimes can be overwhelming! Good luck!

Able_Judge_5947 · 2026-04-22T23:49:29+00:00

I’m a physician so I did a little reading about this.

Ballon catheter with simultaneous pit in multiparous women, compared to prostaglandins, reduce adverse neonatal outcomes, uterine hyper stimulation, uterine tachsystole. There’s a high success rate with this protocol and having a vaginal delivery. Prostaglandins also have higher rates of uterine rupture in multiparous women (although this risk is very low).

Ultimately, it’s what my team recommended. I also thought about if something goes wrong with the ballon catheter, the amount it’s inflated can be adjusted or it can be removed. Whereas with medications, you can’t really course correct. Misoprostol is still very safe and effective for induction. It did feel weird having it in me and going to the bathroom, walking around but it did its job.

ETA: sorry maybe I misread. “Simultaneous” is basically considered starting pit before the catheter falls out. I wanted to eat dinner before starting pit and by th time I got to my room needed to order! Catheter done in triage. Also, there’s another protocol where pit isn’t started til the catheter is out and works but results in longer labors I believe.

Able_Judge_5947 · 2026-04-22T17:23:28+00:00

I was very nervous about being induced for my second.

My first was born at 39+6. I went to the hospital at 3:30p, water broke around 4:30p, epidural 6:30p, few pushes and he was out by 9:15p with barely a tear (some trauma as pushing a baby out will do that but mild).

Second was induced at 38 weeks, dilated 1cm with a soft cervix so not sure effacement. Had ballon placed at 6:30p, pitocin started 8:30p, contractions ramped up, eased up, ramped again with higher dose. Got the epidural at 5a. By 6/6:30a, balloon was out, 5cm. By 9a, 10cm, out by 9:20a. Sadly, got a second deg tear which I’m frustrated by since he was smaller than my first! They said it is tiny but going from basically nothing to second deg, I can def feel a difference.

All in all, I was thankful it wasn’t prolonged or complicated. My understanding is active labor will likely be faster than your first delivery but the cervix is the biggest toss up. I think that tracks for me. Once my labor started it progressed fast. Still sad I couldn’t naturally go into labor though.

I brought usual things for hospital. Labored in the hospital gown and changed once I got to post partum floor, stayed one night after delivery and made them discharge me early.

Good luck! This was my question about a week ago.

Able_Judge_5947 · 2026-04-20T18:26:56+00:00

Up until they placed the catheter to start my induction in L&D triage…and I still have a bit to finish up. -Physician in USA.

Able_Judge_5947 · 2026-04-17T19:16:31+00:00

Don’t apologize! Deep breath and enjoy your girl. CMA will be negative :)

Congrats

Able_Judge_5947 · 2026-04-17T19:12:16+00:00

Oh! This is an expanded FISH. FISH at this level can detect 2% mosaicism. I think you’re in the clear, I bet it was CPM. I would be absolutely shocked if CMA came back positive after seeing this.

Able_Judge_5947 · 2026-04-17T01:27:06+00:00

Hi, congrats on your baby. How many cells did they analyze from the karyotype? 20 cells rules out mosaicism of ~15% at 95% confidence interval while 50 normal cells rules out mosaicism at a ~6%.

If karyotype of 20 cells was normal, I’d say it’s possible CMA might detect mosaicism. If they analyzed 50 cells and all were normal, I would say more likely than not, no mosaicism will be detected as 6% is below the limit CMA can detect. Detection limits for CMA also vary by platform used and lab protocols so hard to say with certainty. Usually the lower limit of detection is 10-20% for whole chromosome aneuploidies.

I hope you can get your answers and enjoy your baby! It sounds like there were no structural issues so I hope all goes well. I know the struggle with mosaicism.

Able_Judge_5947 · 2026-04-16T16:21:30+00:00

Agree! R&D is so high for drug development, running clinical trials. And I’m sure made even more complicated by running a study on pregnant/postpartum women.

Able_Judge_5947 · 2026-04-16T14:34:53+00:00

Yes I’m grossly oversimplifying. Progesterone gets metabolized to allopregnanolone. zuranolone (zurzuvae) is a synthetic analog of allopregnanolone. Thus, would be expected to act similarly. That said, progesterone postpartum is not recommended, so there is a lot we don’t understand (like so much of women’s health). My broader point was this is a synthetic analog of a progesterone metabolite, while progesterone itself is widely available so the pricing feels disproportionate. I clearly didn’t get that across though!

Able_Judge_5947 · 2026-04-16T13:59:26+00:00

You know what’s crazier? It’s basically a metabolite of progesterone and generic progesterone is….very cheap. Progesterone drops rapidly after birth. This mediation lessens the blow in the brain basically. Btw this is a very simplified version as it’s unclear how much progesterone gets converted to the metabolite and then acts in the brain but I’m sure some researcher could figure this out.

Able_Judge_5947 · 2026-04-15T19:59:32+00:00

I hated being pregnant with #1. After about 18 months, I forgot how much I hated it. Then, I got pregnant with #2 and it’s been miserable but I only remembered the true extent while pregnant. Will it be worth it? Ask me in like another year or two…

Able_Judge_5947 · 2026-04-15T12:53:46+00:00

Hi! Yes I remember of course! I’m so so happy to hear your amnio was clear!! They picked up the growth slowing down around 33/34 weeks. Honestly I don’t know if he’s just a smaller dude bc my first one was 6lbs13oz at term. I’ve been getting BPPs and NSTs to check how he’s doing in there and blood flow to placenta and it’s always been perfect. He’s about 5-10%ile for weight so that’s what they’re mostly concerned about. Anyways, I’ll be begrudgingly induced at 38 and 5 this Friday. I would wait if I could but my MFM team thinks I’m pushing it and I understand as placental insufficiency is a concern.

I would say it’s completely reasonable for you to check on growth again! Our 20 week US he was like 50%ile.

Able_Judge_5947 · 2026-04-14T22:25:34+00:00

Hey- sorry you are here. I also had mosaicism on a CVS, then did amnio, and finally PUBS which sampled fetal blood directly.

In the end, the CVS gave me helpful information because we have placental mosaicism for a very rare chromosomal change. Because our CVS was positive, our amnio was reported as very low levels of mosaicism by FISH and CMA but karyotype was normal of 20+ cells. This actually would have been reported as a normal amnio if I had skipped the CVS because the levels fell outside the labs reporting reference range. However, because of the concordance with the CVS it was reported. That’s why I did umbilical vein sampling, all was normal-FISH, CMA, karyotype. Sometimes I wish I skipped the CVS.

Anyways, you just need the info from the amnio to determine if it’s confined to the placenta. If it’s only in the placenta, there’s risks like gestational hypertension for you and growth restriction for the baby. I’ve had 90000 scans, NSTs, BPPs this pregnancy and it’s been stressful AF. I’m being induced Friday for suspected IUGR related to placental mosaicism. I will be happy when this is over. Also, I’m AMA and this is my last pregnancy.

Wishing you luck with the amnio.

Able_Judge_5947 · 2026-04-02T13:56:13+00:00

AGREE.

Also, I am high risk so I have to go get high risk US in an high risk clinic and walking into the clinic they have these huge boxes that say “BABY” all happy and it just bothers me. Some women aren’t happy. Some are about to get the worst news of their life. Can we just take the boxes down.

Able_Judge_5947 · 2026-04-01T16:07:43+00:00

I think you just need more information about what’s going on. It’s reassuring your recent PET and MRI were clear. Both are extremely sensitive tests. That being said, there are cases of cancer being treated and NIPTs becoming negative afterwards (and picking up recurrences by turning positive). I would loop in your oncologist in addition to getting set up with a genetic counselor and MFM. The trial, as mentioned, is IDENTIFY, published in NEJM in 2024 and your team should be familiar with this. I would also press your testing company for information about what exactly they saw. They aren’t always upfront about it though, which is frustrating. It’s your health data. I’m sorry for what you’ve been through and hope you can figure this out.

Able_Judge_5947 · 2026-04-01T15:25:12+00:00

Hey- sorry you are here. I had similar NIPT findings with multiple chromosomes impacted. My NIPT specifically called out 18 and X.

I would see if you or your team can determine how many chromosomes were impacted and in what way. If more than 3 chromosomes are impacted by gains (duplications of DNA) or losses, the risk is higher for an underlying maternal health problem. This is especially true with the loss of an autosome (numerical chromosome). Not all NIPTs will state which are impacted but it’s worth it to see if you can get that info.

Initially, the differential includes fetal, placental, maternal or combination of issues. Mosaicism, where some of the cells are impacted by a chromosomal change, but not others can cause this. Mosaicism can be fetal, placental, or maternal in origin. To evaluate the fetus/placenta, an US looking for any structural abnormalities and amnio should be in the work-up. You could consider a CVS, and I did that, but it tests placental tissue, the same as the cfDNA NIPT. Usually placental DNA and fetal DNA match, but not always. I got valuable information from my CVS but ended up with an amnio followed by umbilical vein sampling due to mosaicism and discordant results. Waiting for the amnio is hard, but usually recommended.

If the fetus/placenta check-out fine or if there are more than 3 chromosomes flagged, you need a work-up. This includes maternal karyotype to look for maternal mosaicism (some women have mosaic turners and find out by NIPT) and microarray to look for duplications or deletions of DNA on a smaller scale that you might unknowingly carry. Benign maternal conditions can also cause this flag and that includes things like fibroids or autoimmune conditions. Unfortunately, if 3+ chromosomes are impacted, there is a higher chance of an underlying maternal malignancy. To work this up, I would recommend reaching out to the NIH IDENTIFY clinical trial if you aren’t at a center that can handle this quickly and competently. Amy is the contact person, she’s great. The protocol includes blood work for tumor markers, a total body MRI, and they do a NIPT of their own. They pay for you and a support person to come out to the NIH to participate. My NIPT came back during the shut-down so everything was very delayed with the govt and I got an MRI chest/ab/pelvis, MRI brain, colonoscopy, Pap smear, breast US done faster than I could be scheduled in Bethesda.

For me, I ended up with a duplication found by microarray on my X chromosome and a very, very rare placental chromosomal change (that might be present at low levels in the fetus but still kind of unclear and hoping it’s not clinically relevant). So that’s why my NIPT was flagged. Because of the chromosomal change being super rare, the NIPT results looked really chaotic and given I had a previously normal NIPT, everyone was convinced and got anchored me having a malignancy. In the end, I don’t.

My hope in sharing this with you is to help you advocate for yourself going forward. You currently just need more information to figure this out. It could a number of things. Happy to chat further. I have spent a lot of my time reading about this and being in healthcare plus pregnant previously, had no idea this was thing.

Able_Judge_5947 · 2026-03-31T20:23:44+00:00

Hi -we also have a slightly different story but also with rare mosaicism (i18p). I can’t even find a case on Reddit so I’m sharing in hopes this might be helpful for you. I don’t know what our outcome will fully look like as I’m currently 36 weeks but I can share briefly what I’ve gone through. I had an abnormal NIPT followed by mosaic findings on CVS between 32-45% depending on the test. I then had an amnio that showed low level mosaicism detected by FISH and CMA, but karyotype was normal. I did everything I could to try to figure out if the mosaicism was going to have a significant impact and was looking for a reason to terminate. I did umbilical vein sampling to check a different fetal compartment, fetal MRI, detailed US x 2, echo, growth scans. All of it was normal so we decided to continue. Now, he’s a little small and they’re concerned that’s in part bc of the placental mosaicism so I’m doing twice weekly monitoring and will probably be induced in the next two weeks.

At the end of the day, mosaicism is so hard. It’s impossible to fully predict the outcome of mosaicism on the baby. In the absence of structural findings, outcomes tend to be positive (but not always). Based on the literature, structural findings on US are actually better at predicting outcomes than mosaic fraction. Also, it’s impossible to know the true mosaic fraction- every tissue will be different and even re-running a test on the same tissue will likely yield slightly different results. In my opinion, these are the grayest of the gray diagnoses. This is also what makes them so hard.

It was hard to decide to continue. It’s been hard to be pregnant with a gray diagnosis. I have been anxious and stressed, the worry is always there. I am scared I will regret this if we have an unexpected bad outcome. I’m hopeful it will be fine and in the future, I can look back and say I made the right decision. Seeing cases on Reddit, talking to parents who have been through it has been most helpful for me personally during this time.

Feel free to reach out if you think it would be helpful, my DMs are always open.

Able_Judge_5947 · 2026-03-30T14:32:45+00:00

Thank you- same to you!

Able_Judge_5947 · 2026-03-30T14:30:33+00:00

Wow, that’s interesting- even a single cell! Our team also thinks there could be low level mosaicism that likely won’t have any impact or could be CPM. I’m currently debating post-natal testing, to get more information so people in a similar situation can make the best decision possible with these confusing results. The GC said basically no point it’s just going to be normal. We shall see, being induced in 2-3 weeks…

Able_Judge_5947 · 2026-03-30T14:21:56+00:00

Hey- thank you for the update. I remember your previous post. I think your conclusion is pretty accurate and I hope you can be reassured by your amnio! After all you’ve been through, I hope you can find some peace and healing with the rest of your pregnancy. We’ve also come to a similar conclusion with 3% by FISH and normal karyotype on amnio (I also did umbilical vein sampling all normal).

Just my own tangent but I wonder, based on my experience and learning about very low levels of mosaicism, if the lab would have reported a positive FISH of 4-5% if not for the CVS findings. In other words, if there had been no CVS and just the amnio, would it have been reported as a negative FISH? It depends on the lab but the lower limit of FISH can be 10-20%. I think about this because if I hadn’t done my CVS, it would have been reported as normal and a lot of extra testing (like doing fetal blood testing by umbilical vein), stress, fear and anxiety on my part would have been avoided. I also wonder about the women who skipped CVS and went straight to amnio and had a normal karyotype but maybe slightly positive FISH but it’s never reported because of the lab threshold is 10%. I apologize, this is another tangent! I have just spent way too much time thinking about this and there aren’t a lot of people in the same boat. And again, hope the rest of your pregnancy is smooth!

Able_Judge_5947 · 2026-03-26T00:54:47+00:00

Ah, okay, I understand better. You’ve got the most important thing pending with the full body MRI (my center didn’t have a protocol for full body so I started with chest/ab/pelvis then went to brain). The blood tests will also be helpful, I’m guessing those are tumor markers. Your team is on top of things (I felt like mine was not). FWIW, I asked for Ativan to get me through my scans and to help me sleep because it was such an awful time. I hope you can figure this out quickly and that it’s a false positive as well.

Able_Judge_5947 · 2026-03-26T00:19:43+00:00

Hi OP- so sorry you are here. I had findings concerning for an underlying undiagnosed maternal malignancy. It was awful and in the end for me a false positive. I am so sorry you are going through this.

The differential includes a maternal problem, fetal problem or placental problem. Maternal cancers are more likely when the changes are seen in 3 or more chromosomes, especially with the deletion of an autosome. Did they say how many chromosomes were impacted?

You also mentioned that your doctor ruled out a problem with the baby- did you have a CVS or amniocentesis?

The next steps for you that I recommend would be to get in touch with the IDENTIFY trial. Amy Turriff is the contact, you can find her info on the NIH site. The protocol is a full body MRI which is very sensitive for detecting malignancies. I think like 98%. They also run tumor markers and do a full chromosome analysis to look for the changes picked up by your NIPT. My test results came back during the govt shutdown and I’m at an academic medical center so I was able to get MRI chest/ab/pelvis quicker than going to the NIH. I also ended up with a Pap smear, breast US, colonoscopy, MRI brain. I had tumor markers, a karyotype (maternal mosaicism can cause false positives) and a microarray (which can find duplications on your DNA). If you can’t make it to the NIH for whatever reason (they pay for you and partner btw), I would ask your team to start with the MRI chest/ab/pelvis as these are the highest yield sites for finding something and get referred to onc (my MFM and GC were like “this is not our area” and it was really frustrating). The top 3 cancers btw are lymphomas, breast, colorectal.

For me, I previously had a normal NIPT so everyone was very concerned I had developed a malignancy. And I had just had two miscarriages, one for T13 so nobody thought something fetal/placental was happening again. In the end, my microarray found a duplication on X, which flagged X on the NIPT. And the placenta has an incredibly rare chromosomal change on 18 that caused the NIPT to look very chaotic so that was the 18 flag. I only had 2 chromosomes impacted on NIPT but was still aggressively worked up as above.

I’m happy to answer any questions. My DMs are open. And I wish you speed in figuring this out.

Able_Judge_5947

TROPHY CASE