Background: There is controversy whether chromosomal microarray (CMA) can replace karyotyping in prenatal diagnosis. Chromosomal microarray may detect more clinically significant chromosomal imbalances than karyotyping in a shorter time but does not detect inversions, triploidies or low mosaicisms.
Case report: Amniocentesis was performed in the late second trimester based on ultrasound abnormalities. A CMA, obtained at 10 days, demonstrated a terminal deletion in 4q34.3-q35.2 and a duplication in 11q21-q25. The karyotype results, obtained 1 week later, showed a derivative chromosome 4 inherited from a maternal balanced 4;11 translocation.
Conclusion: CMA and karyotype were complementary in this case, together permitting a more accurate diagnosis and genetic counseling than if only one method was used.
Keywords: array; derivative chromosome; prenatal diagnosis; translocation.