Applicazione della tecnica MLPA (Multiplex Ligation-Dependent Probe Amplification) per lo screening dei riarrangiamenti subtelomerici in pazienti pediatrici con ritardo mentale | [Application of MLPA (Multiplex Ligation-Dependent Probe Amplification) for the screening of subtelomeric rearrangements in children with mental retardation]

Subtelomeric rearrangements have been reported to be an important cause of mental retardation. These aberrations may remain undetected by routine conventional cytogenetic analysis because of limited resolution in light microscopy. Increased detection of cryptic subtelomeric abnormalities may be achieved by Fluorescence In Situ Hybridization (FISH) which is the most widely used technique in cytogenetic laboratories. However, this assay is expensive and time consuming, because metaphase spreads are needed. Accordingly, FISH is not indicated for broad screening. Multiplex Ligation-dependent Probe Amplification (MLPA) is a new reliable, sensitive and inexpensive technique, which can be used as a high throughput prospective screening tool for subtelomeric rearrangements. The aim of this study was to introduce a novel strategy for the screening of subtelomeric rearrangements in routine diagnosis which consists in a first screening with MLPA then followed by FISH analysis. Methods. We tested 70 children with idiopathic mental retardation both severe and mild, often associated with congenital malformations, growth retardation and/or dysmorphic features. MLPA was performed using SALSA P036E human telomere kit (MRC-Holland, Amsterdam, The Netherlands). If an aberrant MLPA result was observed, FISH with a probe specific for the region of interest was performed to validate the result. Results. Among 70 patients tested, 5 were carriers of unbalanced rearrangements. 3 patients had deletion of 6pter, 2qter and 6qter respectively, one showed a double aneusomy: a distal 21q deletion and 7q duplication and the other one showed a duplication of 13qter. Conclusions. Our preliminary data show a high degree of agreement between MLPA and FISH suggesting that MLPA might be a rapid, accurate, reliable and cost-effective technique for the screening of subtelomeric rearrangements in routine diagnostics.

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