Forensic Implications of the Discrepancies Caused between NGS and CE Results by New Microvariant Allele at Penta E Microsatellite.

Examination of STR markers using the MPS technology is becoming more common in forensic genetics, but scientists still have insufficient experience in dealing with ambiguous results. However, it is always essential to resolve discordant data if we want to use the technology as an accredited method in routine forensic casework. During the internal laboratory validation of the Precision ID GlobalFiler NGS STR Panel v2 kit, we observed two discrepant genotypes at Penta E locus compared to the previous capillary electrophoresis results. Each NGS software that we applied (i.e., Converge, STRaitRazor and IGV) returned the same 12,14 and 12,16 genotypes in the two samples, respectively, instead of the 11.3,14 and 11.3,16 genotypes previously observed with CE (Capillary electrophoresis) typing. In the case of the length variant 11.3 alleles, traditional Sanger sequencing confirmed a complete twelve repeat unit structure in both samples. However, after sequencing was extended to the flanking regions of the variant alleles, sequence data revealed a two-bases GG deletion downstream of the last TCTTT repeat motif in the forward strand. The determined allele variant has not been previously reported in the scientific literature and highlights the need for a careful evaluation and thorough concordance studies before using NGS STR data in forensic cases.

Achromatic luminance contrast sensitivity in X-linked color-deficient observers: an addition to the debate.

It is a matter of debate whether X-linked dichromacy is accompanied by enhanced achromatic processing. In the present study, we used sinusoidally modulated achromatic gratings under photopic conditions to compare the contrast sensitivity (CS) of protanopes, deuteranopes, and normal trichromats. 36 male volunteers were examined. CS was tested in static and dynamic conditions at nine different spatial frequencies. The results support the assumption that X-linked color-defective observers are at an advantage in terms of achromatic processing. Both protanopes and deuteranopes had significantly better CS than controls in both the static and the dynamic conditions. In the static condition, the advantage was observed especially at higher spatial frequencies, whereas in the dynamic condition, it was seen also at lower frequencies. The results are interpreted in terms of decreased chromatic modulation of the luminance channel and the early plasticity of the parvocellular system.