ON ALLELE FREQUENCY COMPUTATION FROM DNA TYPING DATA

Forensic applications of DNA typing data require the estimation of the frequencies of all observed alleles, which is currently done by a fix ed set of groupings (binning) of alleles in a database. Recently it's validity has been questioned on the ground that when a DNA fragment si ze is close to a bin boundary, the frequencies of all adjacent bins sh ould be added. On the contrary, the current forensic database indicate s that when the match window of a DNA fragment overlaps 2 bins, it is enough to consider the bin with the larger frequency, and this never u nderestimates the frequency within the match interval with the current choice of fixed-bin widths. On average, the current fixed-bin procedu re yields an allele frequency at least 2-fold higher than that of a fl oating-bin.