fragmentanalys

Fragment analysis, sometimes noted as fragment analys in some contexts, is a molecular biology method used to determine the size distribution of DNA fragments. It is commonly applied to size PCR products by length, typically ranging from a few dozen to thousands of base pairs. In a typical workflow, DNA is amplified with fluorescently labeled primers. The amplified fragments are separated by capillary electrophoresis and detected by a laser-induced fluorescence system. Size standards run alongside samples calibrate fragment migration, and software converts the detected signals into fragment lengths in base pairs. Alleles at specific loci, especially short tandem repeats (STRs) and other microsatellite motifs, are identified by their fragment sizes, enabling genotype calls at each locus.

Applications are broad. In forensics, fragment analysis underpins STR profiling to generate DNA profiles for comparison. It is also used in paternity and kinship testing, genetic mapping, and quality control in sequencing workflows. Researchers employ fragment analysis for studies of genetic variation, including microsatellite and VNTR analyses, where fragment length reflects repeat number or structure at a locus.

Advantages of fragment analysis include high resolution, the ability to process many samples rapidly, and the feasibility of multiplexing multiple loci in a single run. The method is highly automated and scalable, making it a standard tool in clinical, forensic, and research laboratories. Limitations involve dependence on DNA quality, artifacts such as stutter peaks and pull-up peaks, and the need for careful calibration and interpretation. Cross-platform comparisons require standardized size references and allele-calling conventions.