3p26.3 Microdeletion: Implications for Fetal Health and Development

Amniotic fluid chip genetic abnormality shows a microdeletion of 0.92 Mb at chromosome 3p26.3?

We are already far along in the pregnancy.
Since discovering fetal heart abnormalities at 21 weeks, we underwent amniocentesis and genetic testing.
The genetic testing revealed a deletion, and we went back for additional blood tests for comparison.
By the time the blood test results came back, we were already at 26 weeks.
At that time, the doctor casually mentioned that the deletion was not a concern because I appeared normal, so the fetus should be fine.
However, upon reviewing the written report, I found that it stated: "This microdeletion segment includes one OMIM gene (CHL1).
The deletion of the CHL1 gene may be associated with cognitive and learning disabilities.
The 3p26.3 microdeletion may lead to developmental delays, mild intellectual disabilities, language development issues, and learning disabilities in some cases.
There are also sporadic cases presenting with hypotonia and congenital heart defects.
The phenotypic variability of 3p26.3 microdeletion cases is significant, even among different individuals within the same family.
Due to the variable expressivity of this microdeletion, clinical manifestations and severity can differ widely, and it is recommended to seek genetic counseling from a professional physician." I have relatives with developmental delays and learning disabilities.
Why did the doctor only casually say there was no problem without addressing the concerns outlined in the report? Is it because we are far along in the pregnancy that no further recommendations are given? I am very worried.
What can I do now? Should I just prepare for the risks of delivery?

Michelle, 20~29 year old female. Ask Date: 2020/05/04

Dr. Wu Wanru reply Rare Disease

The information you are looking for pertains to symptoms caused by large deletions in the 3p region, rather than the VOUS (variants of uncertain significance) that you have currently tested positive for.
However, these variants can be found in both normal and abnormal cases, and they are risk factors with less than 100% penetrance, making them difficult to interpret.
Some individuals may focus on the positive aspects, while others may dwell on the negative.
The previous physician may not have elaborated much, possibly because these variants can also occur in normal individuals.
Here are a few suggestions based on the fact that the mother is normal:
1.
If you are concerned that your relative's condition may stem from this, you can ask them to undergo genetic testing as well.
2.
An MRI of the fetus during the third trimester can be performed to observe brain development, which may provide some information.
3.
If you need a second opinion from us, please send all formal written reports to the genetic counselor at Changhua Christian Hospital (extension 7244).
It is important to know the specific gene loci of the deletions to compare with our clinical case database.
Additionally, results may vary slightly between different testing platforms.
4.
Since each family's risk tolerance is different, if possible, please discuss this matter in person with your family for better consultation.

Reply Date: 2020/05/04

More Info

The situation you are facing regarding the 3p26.3 microdeletion is understandably concerning, especially given the potential implications for fetal health and development. The 3p26.3 microdeletion can indeed be associated with a range of developmental issues, including cognitive and learning disabilities, as well as physical manifestations such as hypotonia (low muscle tone) and congenital heart defects. The variability in expression of symptoms, even among individuals within the same family, adds to the complexity of understanding the potential impact on your fetus.

Firstly, it's important to recognize that the presence of a microdeletion does not guarantee that the fetus will exhibit any of the associated conditions. The clinical significance of such genetic findings can vary widely. In some cases, individuals with similar deletions may lead completely normal lives, while others may experience significant challenges. This variability is often referred to as "variable expressivity" in genetics.

Regarding your concerns about the doctor's response, it is possible that the physician was attempting to provide reassurance based on the fact that many individuals with microdeletions may not exhibit significant health issues, particularly if the mother appears healthy. However, the lack of detailed communication about the potential implications of the CHL1 gene deletion and the associated risks may have left you feeling uncertain and anxious. It is crucial for healthcare providers to communicate clearly about genetic findings, especially when they may have significant implications for the child’s health.

Given that you are already 26 weeks along, your options may be somewhat limited, but there are still steps you can take to ensure the best possible outcome for your pregnancy:
1. Genetic Counseling: It is highly advisable to seek genetic counseling if you haven't already. A genetic counselor can help you understand the implications of the microdeletion, discuss the potential risks, and provide guidance on what to expect moving forward. They can also help interpret the results in the context of your family history and the specific findings of your tests.

2. Additional Testing: Depending on the recommendations from your healthcare provider and genetic counselor, you might consider further testing, such as a fetal MRI. This imaging can provide additional information about the fetal brain and heart development, which may help in assessing any potential issues.

3. Monitoring and Support: Regular monitoring of the pregnancy is essential. Ensure that you have a good support system in place, including regular check-ups with your obstetrician and any specialists they recommend. This will help in early identification of any issues that may arise.

4. Prepare for Various Outcomes: While it is natural to feel anxious about the future, preparing for various outcomes can help you feel more in control. This includes understanding the potential needs of a child who may have developmental delays or other health issues, as well as connecting with support groups or resources for families facing similar challenges.

5. Open Communication: Maintain open lines of communication with your healthcare team. If you have questions or concerns, do not hesitate to ask. It is your right to be fully informed about your health and the health of your baby.

In conclusion, while the diagnosis of a 3p26.3 microdeletion can be alarming, it is important to approach the situation with a balanced perspective. Engaging with healthcare professionals, seeking genetic counseling, and staying informed will empower you to make the best decisions for your pregnancy and your child's future. Remember, you are not alone in this journey, and there are resources available to support you.

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You can consult a renowned obstetrician in the area, or call 04-7238595 extension 7244 to schedule an appointment.