The Northern Ireland Regional Molecular Diagnostics Service (RMDS) has relied traditionally on cytogenetic techniques such as karyotyping, fluorescent in situ hybridisation (FISH) and SNP Array to identify and report chromosomal aberrations in constitutional and acquired cytogenetic patients. A pilot study is underway in RMDS to evaluate the clinical utility of optical genome mapping (OGM) using The Saphyr system from Bionano Genomics in prenatal, suspected aneuploidy and complex constitutional cases. Patient samples previously processed using current cytogenetic methods and with known chromosomal aberrations were analysed using OGM and the results from both routes compared for concordance and any additional findings. These cases include chromosomal abnormalities such as trisomies, translocations, copy number deletions and duplications previously identified by QFPCR, karyotyping, FISH or SNP array. Cases will be presented that have been assessed using traditional methodologies and the Bionano Saphyr system and further work is ongoing to assess the additional findings generated from this higher resolution platform.