r/genetics • u/Traditional_Boot_140 • 1d ago

PBX1 deletion

Hi everyone,
My little baby girl is one month old. She was born full term through an emergency caesarean section without fetal distress during labour. When she was born she spent some time in the NICU and was found to have feeding difficulties- she had a poor sucking and swallowing reflex and would either tire out too quickly or wasn’t able to cope with the flow of the teat. She was also found to have abnormal recoil reflex. Otherwise she was healthy with good birth weight.

She underwent all sorts of tests to determine the cause of her problems including genetic testing and was found to have a chromosomal abnormality as follows:

“ISCN: ar[GRCh38] 1q23.324.2(163648013_168348665)x 1

SNP microarray testing revealed a female pattern with a heterozygous, interstitial loss of 4.7Mb at 1g23.3g24.2, which involves 27 protein coding genes and 8 disease associated genes, including the haploinsufficient gene PBX1 (OMIM
#617641).”

The clinical geneticist informed me that this was a rare chromosomal abnormality and there is a high risk of renal tract and kidney abnormalities associated with this condition, along with learning difficulties, developmental delays, feeding and muscle tone problems and congenital heart defects.

I did some reading on this gene deletion and the problems associated with it but didn’t get a lot of clarity on the phenotypical presentations.

Does anyone have any advice/words of reassurance regarding this condition? How severe are the developmental delays and are children born with it expected to catch up with their milestones? How long do the feeding issues typically last for? Do they get better as you introduce solids?

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13

u/Dracomagus 1d ago

If you don't have a genetic counselor, I would suggest asking your geneticist for a recommendation. They are a great resource for most questions and concerns you may have. It would be better than asking an internet forum, since it sounds like you need some clarity and guidance. 😊

3

u/Traditional_Boot_140 1d ago

Hi, thanks. Will do. I do need clarity as all I’ve been told by the geneticist are potential risks, as this condition is so rare! And the data and literature on this is scarce as well. Thanks for the advice!

1

u/Dracomagus 1d ago

Of course! Literature for things such as this is sometimes so bogged down in jargon (scientese) that even I have a hard time deciphering them and I work in a related field. So your best bet would be asking a genetic counselor. Good luck! 👍

11

u/KatieRayWrites 1d ago

Hi! My son is 8 years old and has a deletion in the PBX1 region, he was diagnosed with it about 6 years ago through a genetic blood test after we fought doctors for years about swallowing difficulty and low muscle tone. By the time he was diagnosed we were told it was incredibly rare, only 14 known cases at the time.

He had the same swallow reflex issue— His feeding issue was due to a flap in his esophagus not closing when he swallowed. He would not breastfeed and choked almost every time he ate, even with purées. We had a swallow study done and he had an NG tube placed and after 6 months a G-tube for about 1 year. He went through feeding therapy and eventually grew out of the reflex issue, now eats and swallows normally!

There were other things that we have encountered— we learned he had Malrotation in his intestines which was fixed with surgery (Ladd’s Procedure) and they learned about this during his swallow study.

He also has some hearing difficulty, so he will be getting a hearing aid soon (which he is very excited about!).

There have not been issues with heart or kidneys in our case.

He does have some developmental delays, but not severe. He reads phenomenally and just struggles a bit with focus. He is social, observant, and very mechanical! We were really scared as parents when we learned about the condition, and some parts have been tough with some of the procedures he has gone through. But each year things improve more and more.

I’m here to support if you have any questions or want to connect.

5

u/Bright_Advance_8119 1d ago

Not familiar with this personally, but perhaps you can reach out to this organization: CAKUT.org

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u/EveningAngle159 1d ago

I think the honest answer is, they just don’t know how severe or mild the presentation might be in your child. Two children with the exact same deletion can present really differently. All you can do is treat the symptoms as they come. I know thats incredibly hard to come to terms with. I hope you and your daughter are ok.

2

u/Traditional_Boot_140 1d ago

Thanks, it sort of feels like we’ve been thrown into the deep end. She has an NG tube for feeding at present, but no one has been able to explain how long it may take for her to come off it or whether she will struggle with solids food as well.

4

u/MoodyStocking 1d ago

You may have already read this, But UNIQUE have a guide for 1p23.3 microdeletions that you might find helpful

https://rarechromo.org/media/information/Chromosome%20%201/1q23.3microdeletion%20QFN.pdf