TY - BOOK AU - Nahed Naguib Mohamed Alsabagh AU - Hala Ahmed Elgindy , AU - Mohammed Farouk Mohamed , AU - Walaa Alsharany Abuelhamd , TI - Incidence of pediatric chromosomal abnormalities diagnosed by karyotyping at genetic clinic of Cairo University / PY - 2021/// CY - Cairo : PB - Nahed Naguib Mohamed Alsabagh , KW - Chromosomal abnormalities KW - Genetic disorders KW - Karyotyping N1 - Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Pediatrics; Issued also as CD N2 - Introduction: Cytogenetic studies are very important tools for diagnosis of genetic disorders to provide best possible management and counselling. Chromosomal abnormalities constitute a major category of genetic disorders. These abnormalities can be numerical or structural. They may involve one or more chromosomes or even only a part of a chromosome. Objective: This study aims to describe the cytogenetic profile of all children with suspected genetic disorders referred to genetic unit at Cairo University Children Hospital. Patients and methods: This was Retrospective Record-based descriptive study which was done for all cases referred to Genetic Unit of Cairo University Children Hospital (CUCH) over one year from 2018 to 2019. Results: A total of 600 cases who were referred for Karyotyping; the prevalence of chromosomal abnormalities was found to be 49.9% in all these cases. Numerical abnormalities represented the major category of chromosomal abnormalities found (39.6%), followed by structural abnormalities (10.1%). The present study revealed that Down syndrome (DS) (trisomy 21) was the most common chromosomal abnormality detected (70.2%). Chromosomal nondysjunction was the main cause of DS (90.4%), followed by translocation (6.1%), and mosaic type (2.3%). In this study the median of maternal age of Down syndrome was 34 years and ranged between 17 and 47 years with statistically significant difference between Down syndrome cases and other syndromes found with P value <.05. Syndromic classification of the studied children shows Trisomy 13 (6.4%), followed by Turner (5.7%), Edward syndrome (4.3), Noonan syndrome (1.7%), Klienfilter (1.3%) ER -