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Undetected sex chromosome aneuploidy by chromosomal microarray
Prenatal Diagnosis
|October 5, 2012
Summary
Mosaic Turner syndrome (45,X) and trisomy X (47,XXX) in a fetus was missed by chromosomal microarray analysis (CMA). This occurred due to a normal average X chromosome dosage, highlighting CMA limitations.
Area of Science:
- Reproductive genetics
- Fetal medicine
- Cytogenetics
Background:
- Turner syndrome (45,X) and trisomy X (47,XXX) are common sex chromosome aneuploidies.
- Chromosomal microarray analysis (CMA) is a primary diagnostic tool for detecting chromosomal abnormalities in prenatal settings.
Observation:
- A female fetus presented with mosaicism for both Turner syndrome (45,X) and trisomy X (47,XXX).
- Standard CMA analysis failed to identify the specific X chromosome aneuploidies present in the fetus.
Findings:
- The mosaic nature of the aneuploidy, with a balanced average X chromosome dosage, masked the abnormality during CMA.
- This case demonstrates a potential pitfall of CMA in detecting certain complex chromosomal aberrations, particularly sex chromosome mosaicism.
Implications:
- Clinicians should consider the limitations of CMA, especially in cases with suspected or unexplained fetal findings.
- Alternative or complementary diagnostic methods may be necessary when CMA results are equivocal or do not align with clinical suspicion for sex chromosome abnormalities.
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