Rare Allele 29 at Locus D2S1338 Observed During Routine Casework in Bulgarian Population

In this work, we report a rare allele 29 at locus D2S1338, established during routine forensic practice in a case of first-degree kinship (parenthood). This rare allele variant 29 at locus D2S1338, to the best of our knowledge, is reported for the first time for the Bulgarian population. So far it has not been registered in studies of allele frequencies in the same locus for 20 population groups in Europe and Asia. The presentation of similar genotyping findings relating to rare/unexpected population genetic variation is very important for the examination and documentation of such anomalies. The analysis has been performed for 16 STR loci: D2S1338, SE33, D16S539, D18S51, TH01, D12S391, D3S1358, FGA, vWA, D21S11, D1S1656, D2S441, D8S1179, D19S433, D22S1045, D10S1248 and 2 sex determination systems – Amelogenin and Y indel, set in NGM DetectTM PCR Amplification Kit (Applied Biosystems). The use of allelic witnesses in the diagnostic practice is mandatory in the standard fragment DNA analysis. The allelic witness contains well-known preset alleles for the examined locus. Establishing alleles that are outside the factory preset is of importance for broadening the scope of the witness and heightening the accuracy of the analysis. Rare allelic variants significantly increase the strength of discrimination when DNA profiles are compared. In this regard, it is important to report any new information about the emergence of rare allele variants detected in a particular population group.