Multiplex ligation-dependent probe amplification for the detection of 1p and 19q chromosomal loss in oligodendroglial tumors

Multiplex ligation-dependent probe amplification (MLPA) is a new assay for the detection of multiple chromosomal deletions in tumor tissue in a single experiment. Since genotyping of gliomas with oligodendroglial features by the detection of 1p/19q chromosomal deletions became essential for treatment decisions, we developed and validated an MLPA-based assay to determine these losses in formalin fixed and paraffin embedded oligodendroglial tumors (OG). Nineteen OGs, and 10 control samples were analyzed by MLPA and the results were correlated with those obtained by fluorescent in situ hybridization (FISH). The MLPA results were reproducible in all samples in which repeated experiments were performed. In 18 of 19 OGs, MLPA and FISH were concordant for presence or absence of 1p deletion. In 3 OGs, MLPA detected a 19q deletion not shown by FISH. For the other 15 OGs, MLPA and FISH were concordant. In one sample with 50% to 75% of tumor, MLPA failed to detect the 1p/19q deletions revealed by FISH (though with borderline values of significance). We conclude that MLPA is a valid and reproducible method for the detection of 1p/19q chromosomal deletions in OGs stored on formalin fixed, paraffin embedded tissue.