Abstract
Objective: The aim of this study was presentation of the ultrasonographic findings and perinatal autopsy of cases with rare chromosomal abnormalities. 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. 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. 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.
Highlights
Prenatal diagnosis with conventional cytogenetic analysis has been recognized for more than 30 years as a safe and reliable method for couples at increased risk of having a child with a clinically significant chromosomal abnormality (1)
Some of these numerical and structural chromosomal abnormalities are uncommon in prenatal diagnosis and correlations between these cytogenetic findings and ultrasonographic findings, clinical outcomes of the pregnancies and follow-up of the fetuses with these rare chromosomal abnormalities are very important to provide genetic counseling for further similar cases (3)
We report a single center experience of rare structural chromosomal abnormalities detected during prenatal diagnosis over 17 years and the ultrasonographic and perinatal autopsy findings associated with rare chromosomal abnormalities that are very important for physicians and geneticists in proper genetic counseling
Summary
Prenatal diagnosis with conventional cytogenetic analysis has been recognized for more than 30 years as a safe and reliable method for couples at increased risk of having a child with a clinically significant chromosomal abnormality (1). Detection of chromosomal abnormalities during pregnancy is important for proper genetic counseling and for management of informed decisions about continuing or terminating the pregnancy (2). Some of these numerical and structural chromosomal abnormalities are uncommon in prenatal diagnosis and correlations between these cytogenetic findings and ultrasonographic findings, clinical outcomes of the pregnancies and follow-up of the fetuses with these rare chromosomal abnormalities are very important to provide genetic counseling for further similar cases (3). We report a single center experience of rare structural chromosomal abnormalities detected during prenatal diagnosis over 17 years and the ultrasonographic and perinatal autopsy findings associated with rare chromosomal abnormalities that are very important for physicians and geneticists in proper genetic counseling
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