Chromosomale Mosaike in der klinischen Zytogenetik

In contrast to molecular genetics, in cytogenetic analyses single cells are analyzed individually. This affords an opportunity to detect cells with chromosomal mosaicism. This article provides an overview on problems arising in the detection and interpretation of chromosomal mosaicism in cytogenetic diagnostics. A particular challenge in the diagnostics is to distinguish between clinically relevant genuine mosaicism on the one hand and cultured artifacts, pseudomosaics, age effects, maternal contamination and chimerism on the other. The probability of overlooking mosaicism in cytogenetic routine diagnostics is very high, as on average only 15 of the 10¹² cells in the body are examined and usually only a single tissue is analyzed. However, some cytogenetic mosaics are typical for certain syndromes, such as Pallister-Killian syndrome, cat eye syndrome or Ullrich-Turner syndrome and others are characteristic for certain disorders including some hematological malignancies.