From 1657 specimens of analyzed aborted foetuses during 1992 - 1998, in 7 of 999 successfully cultivated specimens (0.7%) trisomy of chromosome 2 was detected. In one of 7 cases it was the mosaic form. The authors present a case - report of a 34-year old woman with indicated amniocentesis because of high serum alpha-foeto- protein levels. In spite of the normal karyotype of the foetus revealed by PGD, pregnancy was terminated because of the high amniotic fluid alpha-foetoprotein levels and developmental defects detec ted by ultrasound. Autopsy revealed thoracogastroschisis with protrusion of viscera and ectopia cordis, aplasia of the left diaphragm, agenesis of the left kidney, uterus unicornis with hypoplasia of the left adnexum, meningomyelocele in the sacral area, hypoplasia of the left lower extremity and a short umbilical cord with aplasia of one of umbilical arteries. The post-mortem chromosomal analysis of the cultivated embryonal fibroblasts revealed a mosaic with two cell lines 46,XX/47,XX,+2 (78% : 22%). The objective of the paper was to report a rare cytogenetic finding in a severely malformed foetus and to stress the necessity of post-mortem verification of the karyotype established on cultivated amniocytes in all cases of foetal malformations.

        Key words: miscarriage, mosaic form of chromosome 2 trisomy, developmental defects