2023 ACMG Annual Clinical Genetics Meeting Digital Edition: Poster Gallery-Utility of examining 100 metaphase cells in the evaluation of low-level mosaicism

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The article discusses the utility of examining 100 cells in the evaluation of low-level mosaicism in karyotype analysis. The researchers reviewed cases from the University of Michigan Clinical Cytogenetics Laboratory where at least 100 cells were examined. They summarized the number and type of abnormalities found in the initial examination of 20 or 40 metaphase cells, as well as the results of additional cell analysis. The lack of confirmation of low-level mosaicism in more than half of the cases suggests that these mosaicisms are likely caused by cultural artifacts.<br /><br />However, in 24% of the cases, low-level mosaicism was confirmed by additional cell analysis. The enrichment of low-level mosaicism in adult patients suggests that these abnormalities may be age-related and clinically insignificant. The researchers therefore suggest that analyzing 100 cells is not necessary for resolving low-level mosaicism in clinical cytogenetic workup.<br /><br />The article provides a table summarizing cases in which ≥100 cells were analyzed, indicating the indication for the analysis, specimen type, previous karyotype results, and the number of cells analyzed. The majority of cases involved adults and were related to rule out Klinefelter syndrome, azoospermia, oligozoospermia, or Turner syndrome.<br /><br />The article also includes figures comparing cytogenetic results between analysis of 40 cells and 100 cells, as well as examples of karyotypes found in initial analysis. The examples include various abnormalities such as trisomy 21, sex chromosome aneuploidies, and chromosomal losses.<br /><br />In conclusion, the researchers found that analyzing 100 cells is not necessary for the detection of low-level mosaicism in clinical cytogenetics. Most of the low-level mosaicisms observed were likely cultural artifacts. The article provides evidence supporting the use of 20 or 40 cells for karyotype analysis, as recommended in guidelines.

Asset Subtitle

Presenting Author - Aiko Otsubo, PhD; Co-Author - Pierce Cai, Huron High School student; Co-Author - Lynn Knudson-Horneber, BS; Co-Author - Lina Shao, PhD;

Meta Tag

Chromosomal Abnormalities

Clinical Cytogenetics

Cytogenetics

Co-Author Pierce Cai, Huron High School student

Co-Author Lynn Knudson-Horneber, BS

Co-Author Lina Shao, PhD

Presenting Author Aiko Otsubo, PhD

Keywords

examination

low-level mosaicism

karyotype analysis

University of Michigan Clinical Cytogenetics Laboratory

abnormalities

metaphase cells

cell analysis

mosaicism

cultural artifacts

adult patients