A case of discordant related abnormal karyotypes from chorionic villi and amniocytes

A case of three discordant cell lines in prenatal diagnosis is described, of which two were abnormal related structural abnormalities of chromosome 11. One of the abnormal cell lines was seen in all metaphases examined from direct preparations of chorionic villi, the cultured preparations showing an apparently normal male karyotype; the other abnormal cell line was seen in conjunction with a normal cell line in cultured amniocytes. Prenatal diagnosis offered solely on chorionic villus sampling would have yielded a mistakenly normal result on the basis of established criteria for distinguishing true mosaicism from confined placental mosaicism.