Abstract
Purpose: :
We routinely use multiplex ligation-dependent probe amplification (MLPA) to determine copy number variations in chromosomes 1, 3, 6 and 8 for prognostication purposes in uveal melanoma (UM). For quality assessment purposes, we audited MLPA results with those obtained using array CGH and microsatellite analysis (MSA).
Methods: :
Two separate cohorts of UM were examined - Group (A) consisting of 32UM investigated for genetic alterations using both BAC microarray CGH and MLPA; and Group (B) comprising 24 different UM, examined using MLPA and MSA. Further, 10/24 of Group (B) UM were randomly selected and examined by a second independent laboratory using both MLPA and MSA. The investigations were performed in a "blind manner" - i.e. comparison of data was only performed when all investigations were complete.
Results: :
In Group A, both array CGH and MLPA produced successful data for all 32 cases analysed. The data produced using the BAC microarray CGH platform was concordant with all MLPA data, including several cases with mosaicism and unusual patterns of copy number variations.Within Group B, 15UM were monosomy 3 (M3) by MLPA, and of these 14 were also M3 by MSA (93.3% concordance). Nine UM were disomy 3 (D3) by MLPA, and of these 9 were also D3 by MSA (100% concordance). For 20 cases from Group B, MLPA and MSA was performed on DNA extracted from the same sample; for 4 of these cases, MSA had been performed on an earlier biopsy. The 10 UM examined using both MLPA and MSA by an independent 2nd laboratory demonstrated 100% concordance.
Conclusions: :
The findings of this audit supports the continued use of MLPA for UM prognostication as it is a sensitive technology that can detect partial deletions present in UM samples. It can be complimented by MSA, particularly in very small samples with lower concentrations of DNA. The information that MLPA provides allows clinicians to compile an accurate prognosis for most UM patients when combining it with clinical and histomorphological data, at an affordable cost. This information also allows for guidance in counselling patients regarding the most suitable treatment options and in palliative care.
Keywords: uvea • tumors • genetics