[Multiplex ligation-dependent probe amplification analysis of subtelomeric chromosome rearrangements in children with idiopathic mental retardation].

OBJECTIVE: To study the rate of subtelomeric rearrangements in patients with idiopathic mental retardation (MR) and to search the cause of MR. METHODS: DNA was extracted and purified from peripheral blood leukocytes of 180 patients with idiopathic MR. DNA was tested using specific subtelomeric multiplex ligation-dependent probe amplification (MLPA) kits P036B/C and P070 according to manufacturer's instructions. The amplification products were separated by capillary electrophoresis using an ABI 3100 automated sequencer and size standard. MLPA data were extracted by GeneScan Analysis software. Data normalization and analysis were performed with the built-in MLPA application in GeneMarker. RESULTS: Among 180 patients with idiopathic MR, 12 had pathological subtelomeric deletions including 3 cases with a 4p deletion, 2 cases with a deletion at 9q and 22q respectively, 1 case with a deletion at 1p, 7p, 8p, 9q and 12q respectively. Subtelomeric rearrangements were responsible for 7% cases of idiopathic mental retardation. CONCLUSION: Subtelomeric rearrangement is a common cause of idiopathic mental retardation.