What Is The Likelihood Of A Fetus With A Confirmed Diagnosis Of Mosaic Turner Syndrome And A Low-level Mosaicism Of Around 10% In Amniotic Fluid Cells Also Having A Mosaic Trisomy 18, Given The Presence Of Elevated Maternal Serum Screening Markers And A Family History Of Trisomy 18, And How Would This Affect The Interpretation Of The Non-invasive Prenatal Test (NIPT) Results In This Case?
The likelihood of a fetus with mosaic Turner syndrome (10% mosaicism) also having mosaic trisomy 18, given elevated maternal serum markers and a family history of trisomy 18, is low but not impossible. While each chromosomal abnormality typically occurs independently, shared underlying factors in cell division might increase the risk of both conditions co-occurring. However, such dual mosaicism is rare.
The presence of mosaic trisomy 18 could affect the accuracy of Non-Invasive Prenatal Test (NIPT) results. NIPT is effective in detecting common trisomies but may not reliably identify mosaicism, especially if the abnormal cells are present in low percentages. This could lead to false negatives or inconclusive results.
Given these considerations, the following steps are recommended:
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Definitive Diagnostic Testing: Proceed with amniocentesis or chorionic villus sampling (CVS) to obtain a precise diagnosis, as these methods can detect mosaicism more accurately.
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Ultrasound Examination: Conduct a detailed ultrasound to check for any physical markers associated with trisomy 18.
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Interpretation of NIPT Results: Approach NIPT results with caution, recognizing that mosaicism may lead to less reliable outcomes.
In conclusion, while the likelihood is low, the presence of risk factors and the potential for mosaicism affecting NIPT accuracy necessitate further diagnostic testing for an accurate assessment.