Diagnostic testing for Prader-Willi syndrome and Angelman syndrome: A cost comparison

Purpose: Considering cost as a factor, the authors evaluated three approaches to the diagnostic testing of Prader-Willi syndrome (PWS) and Angelman syndrome (AS). Methods: The approaches evaluated were (1) DNA methylation studies followed by fluorescence in situ hybridization (FISH) for any positive DNA result, (2) FISH analysis followed by DNA testing for any negative result, and (3) simultaneous DNA testing and FISH analysis. Results: Of 136 samples submitted for chromosome analysis and DNA methylation analysis for PWS or AS, 114 had a normal chromosome analysis and methylation studies, 9 were positive for AS, 3 were positive for PWS, and 7 had an abnormal chromosome analysis, but not deletion 15q11.2-q13, and normal methylation studies. On the basis of these results, the authors compared the cost of each testing strategy. Conclusion: DNA methylation studies followed by confirmation with FISH for any positive result yields a significant cost savings compared with the other approaches.