Molecular Diagnosis of Prader–Willi and Angelman Syndromes by Methylation-Specific Melting Analysis and Methylation-Specific Multiplex Ligation-Dependent Probe Amplification

cases have deletions at a common region in chromosome 15q11.2-q13, uniparental disomy for chromosome 15 (UPD15), or imprinting center defects affecting gene expression in this region. The resulting clinical pheno-type (PWS or AS) in each class of genomic abnormalities depends on the parent of origin. Both disorders are characterized at the molecular level by abnormal meth-ylation of imprinted regions at 15q11.2-q13. Other rare chromosome 15 rearrangements and a few smaller atyp-ical deletions associated with abnormal methylation patterns also have symptoms overlapping with either PWS or AS. Methods: We designed a methylation-specific melting analysis (MS-MA) method for a rapid screening of PWS/AS and evaluated methylation-specific multiple