A silent allele in the locus D19S433 contained within the AmpFlSTR Identifiler PCR Amplification Kit.

We present two cases where a single locus mismatch was found in the locus D19S433 using the AmpFlSTR Identifiler PCR Amplification Kit (Applied Biosystems) (Identifiler Kit) during paternity and maternity tests. This mismatch differed from the mismatch pattern where there is usually a one repeat difference. We designed forward and reverse primers so that they were positioned further away from the primer set contained in the Identifiler Kit. The results showed the existence of a silent allele 13 in both families, due to a point mutation that changed guanine to adenine at 32 nucleotides downstream from the 3' end of the AAGG repeat sequences in all four members. A single locus mismatch due to a silent allele may occur in any locus using any kit. Accordingly, we should pay attention to this silent allele when carrying out human identification and parentage analysis.