Complete karyotype discrepancy between placental and fetal cells in a caseof ring chromosome 18

A case of complete karyotype discrepancy between cultured chorionic villi a nd amniotic in addition to fetal cells is reported. Ring chromosome 18 acid monosomy 18 mosaicism was detected after amniocentesis. The pregnancy was terminated in the 23rd gestational week. Cytogenetic analysis of cultured u mbilical cord tissue after termination confirmed the finding of ring chromo some 18/monosomy 18 mosaicism. In cultured umbilical blood lymphocytes mono somic cells 45,-18 were not detected and the karyotype was 46,XY,r(18). In contrast, short-term and long-term cultured chorionic villi showed a normal male karyotype of 46,XY. Ultrasonographic examination revealed amniotic ba nd syndrome and scoliosis in the caudal region of the spine. Copyright (C) 2001 John Wiley & Sons, Ltd.