Detection of Mosaicism in amniotic fluid cultures: A CYTO2000 collaborative study

Purpose: To evaluate the assumptions on which the American College of Medic al Genetics (ACMG) Standards and Guidelines for detecting mosaicism in amni otic fluid cultures are based. Methods: Data from 653 cases of amniotic flu id mosaicism were collected from 26 laboratories. A chi-square goodness-of- fit test was used to compare the observed number of mosaic cases with the e xpected number based on binomial distribution theory. Results: Comparison o f observed data from the in situ colony cases with the expected distributio n of cases detected based on the binomial distribution did not reveal a sig nificant difference (P = 0.525). Conclusions: The empirical data fit the bi nomial distribution. Therefore, binomial theory can be used as an initial d iscussion point for determining whether ACMG Standards and Guidelines are a dequate for detecting mosaicism.