Fetal mosaicism, should conventional karyotype always be performed?

Abstract

AbstractThe application of classical cytogenetic and DNA-based molecular techniques to detect cell lineages of mosaicism derived from cultured or non-cultured fetal cells may result in discordant results. This retrospective study aimed to assess the inconsistent diagnostic outcomes, technical availability, and limitations of chromosomal microarray analysis (CMA) and karyotyping for mosaicism. A total of 75 fetuses diagnosed with mosaicism by karyotype analysis or CMA were selected, and the results from both the methods were compared and further analyzed.A total of 42 (56%, 42/75) CMA results were consistent with karyotypes, consisting of 22 cases of mosaic sex chromosomal abnormalities, eight routine autosomal aneuploidy cases, eight other autosome aneuploidy cases, three large cryptic genomic rearrangements, and one small supernumerary marker chromosome. Discrepancy between karyotype analysis and CMA was observed in 33 (44%, 33/75) mosaicisms involving 15 sex chromosomal abnormalities, one routine autosomal aneuploidies, five other autosome aneuploidy cases, eight large cryptic genomic rearrangements and four small supernumerary marker chromosomes. Considering the disparities between methods as well as the cell populations analyzed, both CMA and karyotype analysis have their own advantages and disadvantages. Therefore, CMA should ideally be used in combination with karyotyping to detect more cases of mosaicism than using either test alone.