Publication details

Detection of subtelomeric aberrations as a cause of mental retardation



Year of publication 2010
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description Mental retardation (MR) is a various manifestation of dysfunction in the central nervous system. It is a major health care problem in developed countries affecting between 2-3% of population. It’s due to heterogeneous causes including environmental factors (15%), chromosomal abnormalities and monogenic disorders (30%). The cause of MR is unexplained in about 55% of cases. In the past few years it was emerged that a significant number of subtelomeric changes (about 5-8%) were detected in patients with idiopathic mental retardation as a cause of their disease using new sensitive methods of molecular cytogenetics as for example MLPA (Multiplex Ligation-dependent Probe Amplification). The detection of chromosomal rearrangements is usually done by routine analysis of G - banded metaphase chromosomes (karyotyping). It’s the basic cytogenetic method very important to detect balanced and imbalanced chromosomal changes. However, the G-band analysis has limited resolution and it can not detect aberration smaller than 5 Mb. The new methods of molecular cytogenetics have significantly increased this resolution. MLPA is one of the molecular methods used to uncover imbalanced changes (deletions and duplications). Due to a high cost of the whole genome screening methods, many studies analyze only a selected part of human genome – the physical ends of chromosomes (subtelomeres). This technique is based on PCR amplification of ligated probes hybridized to chromosome ends. Therefore MLPA was adapted for subtelomeric screening in patients with unexplained mental retardation in routine diagnostics. Over 160 patients with unexplained mental retardation were investigated using MLPA at Department of Medical Genetics, University Hospital Brno since 2007. We have detected 11 various subtelomeric aberrations (8 deletions and 5 duplications), suggesting a prevalence of 6,7% in our group of patients. This number of positive capture corresponds to international studies with the similar genetic focus.
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