Characterization of a Rare Mosaicism in Autosomal Translocation of t(5;21) Using Conventional Cytogenetics and FISH Methods

• Main Authors: Sadaf Omori Sarabi, Javad Karimzad Hagh, Claudia Behrend, Seyed Behrooz Mohseni, Mitra Ansari Dezfouli, Seyed Khalil Rashidi, Mir Davood Omrani
• Format: Article
• Language: English
• Published: Pasteur Institute of Iran 2020-01-01
• Series: Iranian Biomedical Journal
• Subjects: partial monosomy 21q; translocation t(5;21)
• Online Access: http://ibj.pasteur.ac.ir/article-1-2770-en.pdf
• ISSN: 1028-852X; 2008-823X

Background: Mosaicism of a normal cell population and an unbalanced autosomal chromosome rearrangement is rarely seen. If the abnormal cell line contributes to a minor part of soma, the phenotype is expected to be normal. Case Report: We report a 29-year-old woman who had balance chromosomal translocation of 46,XX,t(5;21) with a two-year-old affected girl, characterized by mental retardation, dystrophia, hearing impartment, and dysphagia. Methods and Results: Cytogenetic investigation revealed a low mosaic unbalanced translocation of 46,XX,t(5;21)/ 46,XX, which was confirmed by FISH analysis. Studying 200 metaphases and interphases of peripheral blood sample revealed 70% partial monosomy of 21q22 and partial trisomy of 5q(35.3) and 30% of normal pattern. Conclusion: In rare cases such as this study, parents with balanced translocation with no phenotypes may lead to a mosaic unbalanced translocation with abnormal phenotypes in offspring, which underscores the need for prenatal karyotyping and genetics counseling.