Testing strategies for imprinting disorders (ID) based on initial methylation analysis (
A
) or simultaneous methylation and CNV analysis by MS-MLPA (
B
). *Karyotype analysis to test for structural chromosome rearrangements can be initiated at the same time as methylation analysis if this is a known cause for an ID. **If all testing is negative, but the phenotype is highly suggestive of a specific ID, testing of another cell type (skin fibroblasts, buccal cells) can be considered to detect somatic mosaicism. ***In the majority of cases, an ID will be due to an idiopathic methylathion change, however depending on the resolution of previous CNV analysis, testing for ICR microdeletion/microduplication can be performed to rule out inherited genomic alterations.