Double Chromosomal Abnormalities in Live Birth Infants
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- Category: Vol. 77, September 2009
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Double Chromosomal Abnormalities in Live Birth Infants,NAGWA A. MEGUID, SAHAR EL BAYOUMI, HODA BASHEER, NAGHAM ELAMEER, SAIDA A. HAMMAD, HASSAN A. HOUSIEN, LAILA A. HOSNY and AMAL M. MOHAMAD
Abstract
Objectives: The aim of this study was to present rare cases with coexistence of double chromosomal abnormality involving chromosome 21 and to discuss different mechanisms of double anomaly in live births for better counseling.
Introduction: The coexistence of two chromosomal ab-normalities in the same individual is relatively a rare phenom-enon. Most of the previously reported cases of double abnor-mality were found in spontaneous abortions. Multiple chromosomal abnormality occurs as a consequence of a minimum of two errors during meiosis. The zygote carrying a double anomaly usually results from a double error in a single germ cell. However the coincidence of a single anomaly occurring in both gametes was also observed.
Material and Methods: In this study, we described nine live births with double chromosomal abnormality involving chromosome 21. Cytogenetic studies and fluorescence in situ hybridization (FISH) analysis were carried out for all infants and their parents. The first new born had double trisomy involving chromosomes 21 and X in a female infant (karyotype 48,XXX,+21). Second and third cases had both trisomy 21 and trisomy 18 (karyotype 48,XX,+21,+18) the fourth case had apparent monosomy 21 and trisomy 18 (karyotype 46XX,- 21,+18). Cases 5-9 had trisomy 21 associated with deletion or translocation. In all cases the double chromosomal abnor-mality is de novo except in cases 1 and 6.
Conclusion: We concluded that genetic counseling in such cases is difficult. Neither satisfactory data concerning the clinical outcome of the double chromosomal anomaly in live infants nor any information concerning the recurrence risk for their parents. However, we recommend the study of different tissues to parents of children with de novo double chromosomal anomaly.