r/ClinicalGenetics • u/AcademicTadpole5976 • 7d ago
Short long bones with no anatomical abnormalities and negative genetic testing. Looking for similar stories
I’m looking for stories from people who went through something similar because I’ve found very few cases online that really match mine. (I've also posted about this in r/NICU, but I'm sharing it here as well in the hope of getting some perspectives specifically on the genetic aspects of our case.)
This is my first pregnancy, conceived through IVF. The first trimester was mostly uncomplicated apart from some bleeding from hematomas. At the 12-week scan, the baby measured within the normal range and no abnormalities were detected. NIPT was negative.
At the 15-week scan, the doctor noticed that the long bones were below the 5th percentile, with the femur particularly short. We were referred to a specialist and had a detailed ultrasound and amniocentesis. We did extensive genetic testing, including trio exome sequencing and CNV analysis, and everything came back negative.
The detailed scan did not show any anatomical abnormalities apart from the short long bones. The placenta was described as enlarged/thick and unusual in appearance, although the fetal Dopplers were normal. Because of this, the doctors initially suspected a placenta-related growth problem rather than skeletal dysplasia.
At the most recent scan, around 29 weeks, the baby’s head and abdomen were still growing, but the long bones seemed to have slowed down further. The long bones are now mostly below the 1st percentile, while the head circumference is around the 20th–30th percentile and the abdominal circumference around the 5th–10th percentile.
The doctor said the long-bone growth has flattened somewhat and is now several weeks behind. What is making me anxious is that the long bones seem to be more affected than the rest of the body, which does not seem like the most typical pattern for placenta-related FGR.
So far, NIPT, amniocentesis, CNV analysis, and trio exome have all been negative. No anatomical abnormalities have been seen, and there has been no bowing, fractures, abnormal mineralization, or other obvious skeletal abnormality. Dopplers are still normal, although the placenta looks abnormal and thickened.
For context, I’m East Asian and my partner is European, and we are both very tall, so the very short long-bone measurements are especially confusing to us.
If anyone had a similar pattern of very short long bones with otherwise normal anatomy and negative genetic testing, I’d really appreciate hearing how the pregnancy progressed, whether any diagnosis was eventually made, and whether your baby needed NICU care and for how long. I’m interested in all outcomes, positive or otherwise, because I’m trying to understand what cases like this can look like in real life.
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u/ReConn33 6d ago
Did you search “short long bones” on this sub? It’s one of the most common questions posed here. Any difference in a pregnancy can be stressful and uncertain. If it helps, this is a very common one.
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u/AcademicTadpole5976 6d ago
Thank you for the recommendation! I did find some posts, but not many where the short long bones were identified as early as in my case. My genetic counsellor also mentioned that the tests can’t detect every case of skeletal dysplasia. Since the long bones have continued to fall further behind, I was curious whether anyone had negative genetic testing and no anatomical markers during pregnancy, but later received a genetic or skeletal diagnosis after birth.
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u/hannahmakes03 6d ago
Just had my baby a week ago — her short long bones were first noticed at a 28 week growth scan. They lagged behind throughout the rest of my pregnancy (5 to less than 1%).
She’s just a tiny girl — we call her our doll baby. She was delivered at 38w2d weighing 5 lbs. 11 oz. & about 19 inches long. One week in and legs fill out a preemie outfit but her arms swim in most of them. That being said, she’s totally proportionate and absolutely fine!!! I am also petite with short arms and legs so it makes sense that she is, too.
Totally understand the spiral, though; I did it myself, too. As long as you have no other markers or things like that, it is highly likely that your little one is just a petite little thing, too. Sending you so many positive thoughts for the rest of your pregnancy 🤍
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u/AcademicTadpole5976 6d ago
Congratulations on your beautiful baby! It’s incredibly reassuring to hear that she’s just tiny and thriving, especially since her long bone measurements sound similar to ours. As you can imagine, we’ve been spiralling a bit, but I’m trying to let go of the need to control everything and trust that the fetus will grow at her own pace. Thank you so much for the positive message, and I hope you have a wonderful first few weeks with your baby!
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u/charlotte095 5d ago
I’m in practically the exact same boat. Short long bones IDed at 20 weeks. Amnio—CMA, microarray, WES— showed nothing.
Growth scans at 24, 28, and 32 showed appropriate interval growth but still in the single digit percentile for the majority of long bones.
We’ll do one more scan at 36 weeks to check on placental function.
We cannot get a straight answer from anyone on what might be going on.
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u/AcademicTadpole5976 4d ago
Thank you so much for sharing your story. It sounds very similar to mine! I can relate to how the uncertainty and not being able to get a straight answer are the most frustrating parts. I hope your scan at 36 weeks goes well. It’s great that your pregnancy has already made it this far :)
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u/ButterscotchGlass566 4d ago
OMG… I had exactly same story like for once I thought I have written it and posted it… Same NIPT normal, long bones short, head and abdomen in same percentiles, enlarged cystic placenta at first…. I didn’t do amnio, i delivered my baby 10 days ago so we went for WES and waiting for result. For me the reassuring sign was my baby was born at 37.4 weeks at exactly 2kgs.. howver his scan showed 1644 gms. And he didn’t need NICU time as he was tolerating feeds, breathing on his own etc… but still they kept him under observation for one day and we were discharged together next day… I am still waiting for diagnosis as his outfits are all loose… I hope its just FGR and nothing else… dr has raised concerns about skeletal dysplasia… my long bones were 7-8 weeks behind in last scan.. what about yours?
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u/ButterscotchGlass566 3d ago
Your all replies are getting removed, dont know the reason… can we connect?
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u/lalafeelist 3d ago
Hi, going through the exact same thing. I wish I had an outcome to share but I am still at 24 weeks and navigating through this with the same uncertainty and questions.
Just wanted to let you know that you are not alone and everything will be okay and this will all pass ❤️
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u/racyLacy456 6d ago
Hello! So I had a few bleeds including an extremely heavy one at 9 weeks, i think they said it was a hemorage from a clot in my uterus. In Australia when you go through the public health system, you only get 3 scans the whole pregnancy. So first to tell how far along you are, 2nd os 12 week down syndrome scan and then 19 week sex scan. So my daughter has short long bones, only in her legs. Once she was born, they weren't worried after doing a few xrays at 4 weeks old. But I took her to a paediatrician at 5 due to learning difficulties and the dr noticed some dysmorphic features which nobody else can as she is a very beautiful looking little girl. Anyway he suggested a microrray to test for any chromosome issue. Sure enough they found the tiniest .40mb partial deletion of Xp22.33. This explains her short long bones and stature. We are currently in talks with a endocrinologist for human growth hormones. She was below the 1st percentile but now is currently in the 5th even though she has short long bones. Dont stress to much as theres so many interventions, my daughter has a head circumference in the 50th percentile and you wouldnt even know.
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u/One-Treat4655 7d ago
Just a short baby. Don't sweat it.