Chromosome and interphase analysis of placental mosaicism in intrauterine growth retardation.

[monosomy 21]

Confined placental mosaicism is found in a higher percentage of cases of unexplained intrauterine growth retardation (IUGR ) than in those of normal pregnancies . To test this hypothesis of cytogenetically abnormal placental cells associated with IUGR , we identified patients in whose fetuses IUGR was suspected during the antepartum period by clinical and serial ultrasonography and Doppler examinations and confirmed by immediate neonatal physical examination . At birth placental biopsy samples and cord blood were collected and coded . Similar specimens were obtained from non-IUGR pregnancies during that period to avoid bias in evaluation of results . These specimens were processed for standard cytogenetic studies and fluorescent in situ hybridization (FISH ) of interphase cells to detect any chromosomal mosaicism in a double -blind fashion . Results were obtained on 26 IUGR placentas . Of these placentas , 22 were cytogenetically normal on standard karyotype analysis and interphase fluorescent studies . Four placentas were shown to have some chromosomal aneuploidy : one with the same chromosome anomaly in multiple cells and the other with multiple single -cell aneuploidy . Of these placentas , cytogenetic and FISH studies showed one to have a monosomy 21 cell line , two placentas showed mosaicism on karyotyping , which was not confirmed by FISH , and one placenta had a suggested chromosomal instability . All placentas had normal anatomy regardless of the chromosome findings and no chromosome anomalies were seen in any of the infants . Non-IUGR placentas showed no chromosomal-confined mosaicism and all had normal findings on placental pathologic examination .