title: Rare structural chromosomal abnormalities in prenatal diagnosis; clinical and cytogenetic findings on 10125 prenatal cases.
abstract: Objective: The aim of this study was presentation of the ultrasonographic findings and perinatal autopsy of cases with rare chromosomal abnormalities.
  
  
  METHODS
  A total of 10125 prenatal cases over 17 years including 8731 amniocentesis, 973 chorionic villus sampling, and 421 fetal blood sampling cases were evaluated for prenatal cytogenetic diagnosis. Conventional cytogenetic studies, fluorescence in situ hybridization studies, and Array-CGH analysis techniques were used for genetic analysis.
  
  
  RESULTS
  A structural chromosomal abnormality was observed in 95 cases. The most frequently observed structural abnormalities were balanced translocations with a frequency of 53.7% (51 cases) followed by unbalanced translocations (16.8%), inversions (11.6%), supernumerary marker chromosomes (8.4%), duplications (4.2%), deletions and ring chromosomes (2.1%) and complex translocation (1.1%). Rare structural chromosomal abnormalities including de novo balanced translocations, unbalanced translocations, inversions, duplications, deletions, ring chromosomes, and supernumerary marker chromosomes were detected in 24 cases.
  
  
  CONCLUSIONS
  The rate of rare chromosomal abnormalities varies from 2.4% (South East Ireland) to 12.9% (Northern England) in Europe with a total rate of 7.4/10 000 births. In our study, the overall rate of chromosomal abnormality in prenatal cytogenetic diagnosis was 3.7%, similar to South East Ireland. Ultrasonographic and perinatal autopsy findings of the cases with rare structural chromosomal abnormalities are important for proper genetic counseling for further similar cases.
authors.forename: Sezin
authors.initials: S
authors.lastname: Yakut
authors.forename: Zafer
authors.initials: Z
authors.lastname: Çetin
authors.forename: Mehmet
authors.initials: M
authors.lastname: Şİmşek
authors.forename: Ibrahim Inanç
authors.initials: II
authors.lastname: Mendilcioğlu
authors.forename: Havva Serap
authors.initials: HS
authors.lastname: Toru
authors.forename: Sibel
authors.initials: S
authors.lastname: Berker Karaüzüm
authors.forename: Güven
authors.initials: G
authors.lastname: Lüleci
mesh_terms: D000649:Amniocentesis; D001344:Autopsy; D002869:Chromosome Aberrations; D025063:Chromosome Disorders / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology; D055028:Comparative Genomic Hybridization; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D005838:Genotype; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D010641:Phenotype; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D014421:Turkey; D016216:Ultrasonography, Prenatal