Case Report

De novo mosaic marker chromosome detected in prenatal diagnosis

  • Özge Özalp Yüregir
  • Zerrin Yilmaz
  • Feride Iffet Sahin
  • Banu Bilezikçi
  • Filiz Yanik

Turk J Obstet Gynecol 2008;5(1):17-21

AIM: Marker chromosomes are structurally abnormal chromosomes which can not be identified by conventional cytogenetic methods. The incidence of marker chromosomes in prenatal diagnosis has been reported to be between 0.04% and 0.15%. Here, we aimed to report a case with marker chromosome mosaicism detected in prenatal diagnosis. CASE PRESANTATION: The fetal karyotype of a patient whose amniotic fluid was sent to our laboratory for increased risk of Down Syndrome in maternal serum screening was found to be 47,XX,+mar[4]/46,XX[27]. In order to evaluate the mosaicism in a different tissue, cord blood sampling was performed and the result revealed a 47,XX,+mar[15]/46,XX[85] karyotype. After verifying the parental karyotypes as normal, the parents were informed about de novo unbalanced chromosome abnormalities; who then decided to terminate the pregnancy. Minor abnormalities were examined on macroscopic pathological examination of the fetus. CONCLUSION: The fetal abnormality was evaluated as de novo mosaic marker chromosome. Information about the genetic condition and the risk for the current and future pregnancies was given to the couple during genetic counseling. The second pregnancy of resulted in a live born baby with a normal karyotype.

Keywords: Marker Chromosome, Mosaicism, Prenatal diagnosis