Author: Li, Kai Man Samuel
Title: Application of array-comparative genomic hybridization (aCGH) in prenatal samples with 15q11-q13 duplication
Degree: M.Sc.
Year: 2014
Subject: Comparative genomic hybridization.
Hong Kong Polytechnic University -- Dissertations
Department: Department of Health Technology and Informatics
Pages: x, 50 leaves : color illustrations ; 30 cm
Language: English
Abstract: Chromosomal 15q11-13 contains imprinted genes which are essential for human neurodevelopment, and aberrant chromosomal changes in paternal or maternal 15q11-13 alleles results in Prader-Willi (PWS) or Angelman syndromes (AS)1, respectively. Prader-Willi syndrome was found in the paternal deletions of 15q11-13 and cause neurodevelopmental disorder. While Angelman syndrome was found in maternal deletions, which cause severe mental retardation and distinct neurodevelopmental disorder. For 15 q duplication, additional maternal duplications in 15q11-13 lead to a distinct condition that includes autism (AU) and varying degrees of learning disability. Recent studies found that paternal duplications of the 15q11-13 region show a distinct phenotype. In order to investigate the effect of cytogenetic abnormalities and breakpoints in the locus at 15q11-13, study the chromosomal location and the identification of regions containing abnormal genes which may predispose to certain disease. The conventional cytogenetic chromosome analysis has been the gold standard for examines chromosomes abnormalities in prenatal diagnosis. It is used to investigate the structural changes in chromosome through microscopic examination of metaphases, with a limited resolution power of lesser than 10Mb. Array-comparative genomic hybridization (aCGH) which overcomes the limitations and offers higher resolution power than conventional cytogenetics in detecting submicroscopic changes and in identifying chromosomal breakpoints by whole genome screening. This study is to investigate the 18 prenatal samples with 15q11-q13 duplication by aCGH which were diagnosed by conventional cytogenetics. Results of aCGH were not consistent with cytogenetic results, only 4 cases with chromosome 15 q11-q13 duplication and the remaining 14 cases shown normal genotype. This study demonstrates the non-concordance may due to the variation of euchromatic and heterochromatic variants on chromosome 15. By using aCGH, it can distinguish the normal euchromatic and heterochromatic variants from pathogenic duplications including PWACR in 15q11-q13 and provide more information on the breakpoints of genomic imbalance. In addition, aCGH can shorten the reporting time and reduce the labor cost for performing the unnecessary tests. To conclude, our data suggest that the application of aCGH may be used for better characterize the 15q11-q13 duplication in prenatal setting.
Rights: All rights reserved
Access: restricted access

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