Different diagnostic methods are applied to determine clinically relevant genetic markers in CLL. Fluorescence in situ hybridization (FISH) is performed to detect the deletions of 11q, 13q, and 17p, as well as trisomy 12, whereas the IGHV and TP53 mutation status is determined by sequencing (Sanger sequencing and/or NGS). Karyotypic complexity is determined by cytogenetic analysis, counting both numerical and structural chromosomal aberrations.