The DNA Integrity Number: A Novel Approach for Objective Integrity Classification of Genomic DNA Samples

Genomic DNA (gDNA) is used as starting material in the experimental workflow of many applications in molecular biology. The integrity of the DNA critically affects the success of many downstream experiments like array CGH or sequencing. Initial electrophoretic analysis of the sample is highly recommended as the respective downstream applications can be expensive and time consuming. The Agilent Genomic DNA ScreenTape Assay has been primarily developed for the electrophoretic analysis of genomic DNA samples. A ScreenTape is a pre-packaged microfluidic device designed for performing electrophoretic applications in a microscale format. It is used in combination with the Agilent 2200 TapeStation instrument. Degradation of gDNA is typically a gradual process in which high-molecular weight DNA is fragmented into smaller species. It can occur either enzymatically, chemically or mechanically. Judging the integrity of DNA by visual evaluation of the electropherogram trace is subjective and can be error-prone. In order to standardize this a novel algorithm was developed to score gDNA samples on the 2200 TapeStation. The DNA integrity number (DIN) is calculated from several features obtained from the electrophoretic trace and ranges from 1 to 10. Here we show data demonstrating the reproducibility, scalability and linearity of the DIN. The DIN is independent from instrument, reagent and sample concentration variability and can be used as objective measure for determining the integrity of gDNA.