Cytogenetic and molecular characterization of patients with 22q11.2 deletion syndrome / Khaled Mohamed Refaat Dakhly ; Supervised Hoda Mohamed Abdelghany , Rania Mohamed Samy , Mona Kamal Mekkawy

Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Clinical and Chemical Pathology

22q11.2 Deletion Syndrome (22q11.2 DS) is one of the most common genetic causes of learning disability. It is caused by hemizygous microdeletions on chromosome 22q11.2. The aim of the work was to detect 22q11.2 deletion in patients with phenotypes suggestive of the 22q11.2 deletion syndrome (cardiac, velopharyngeal, craniofacial) in order to reach accurate diagnosis for proper genetic counseling and further management. Cytogenetic and molecular analyses of 20 cases with 22q11.2 DS features were preformed by conventional cytogenetic analysis (CCA) and Fluorescence insitu hybridization (FISH). Multiplex Ligation Dependant Probe Amplification (MLPA) analysis was done for cases clinically suspected of being affected with 22q11.2 DS and showing no deletion by FISH analysis. CCA revealed two cases (10%) showing deletion in the 22q11.2 region. FISH revealed 4 cases (20%) showing 22q11.2 deletion. The results of MLPA analysis were concordant with the results of FISH analysis, as patients without detectable deletion (80%) showed no deletion using MLPA analysis. In conclusion CCA can diagnose 22q11.2 DS with large deletion. The cytogenetic diagnosis can be greatly improved by using FISH analysis, which detects typical deletion while atypical, or distal deletion can be detected by MLPA analysis

Issued also as CD