engleski

Evaluation of subtelomere imbalance in patients with mental retardation detected by MLPA screening

Cryptic subtelomeric rearrangements are considered to be a significant cause of idiopathic mental retardation (MR). Subtelomeric Multiplex Ligation dependent Probe Amplification (MLPA) analysis has increasingly been used as an adjunct to routine cytogenetic testing and a relatively low cost and high throughput screening for the detection of small cytogenetically invisible telomeric rearrangements. We have studied a series of 50 unselected patients with idiopathic mental retardation and negative chromosomal analysis. Two commercial kits from MRC Holland, SALSA MLPA kit P036C and SALSA MLPA kit P070 probe mixes were performed for subtelomere screening. The MLPA screening revealed chromosome aberrations in two (4%) cases: one patient with terminal deletion of the long arm of chromosome 22 and one case with double subtelomeric aberration consisting of a 12p deletion associated with 22q duplication. The chromosomal breakpoints and deletion size were subsequently characterized and evaluated by quantitative fluorescent-polymerase chain reaction (QF-PCR) using polymorphic short tandem repeat (STR) markers and additional MLPA specific telomere probe mix. In conclusion, MLPA subtelomere screening is a fast, sensitive and cost-effective technique for screening idiopathic mentally retarded patients with normal karyotype. Confirmation and detailed characterization of breakpoints by another molecular method and MLPA follow-up kit for specific telomere is needed to refine genotype-phenotype correlation.

MLPA

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