In this issue, Drs. Sun Ho Lee and Wung Joo Song report copy number variations in 42 Korean patients with unexplained developmental disorders by chromosomal microarray (no chromosomal alteration was detected by conventional karyotyping or fluorescent in situ hybridization). They found clinically relevant copy number variations in over 60% of tested patients, which suggests the superior diagnostic performance of chromosomal microarray analysis. Dr. Sun-Young Kong’s group observed chromothripsis events in several myeloma cell lines and bone marrow samples of multiple myeloma patients. They found that the number of chromothripsis-like events increased after drug treatment and that chromothripsis-like events were more frequent in the drug-resistant group. Dr. Heui-Soo Kim’s group explored the evolutionary conservation of miR-21-3p in various species and the expression patterns of target genes in olive flounder. In the application note section, Dr. Buhm Han’s group report an interesting tool, called ‘MergeReference.’ This tool supports the imputation of human leukocyte antigen genes using intergenic single nucleotide polymorphism markers.