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Author:
Sahil, Arun Singha, Ishita Gairola, SJachin, ⁠Shivam, Ashutosh Kainthola, Jitesh Kumar, Ritu Bala, agjeet Singh, Prohit Jumnani, Ritik Dogra, Ankita Singh, Narotam Sharma, Ajay Singh
DNA Labs – CRIS (Centre for Research & Innovative Studies), East Hope Town, Dehradun, Uttarakhand, India

DOI: doi.org/10.58924/rjmp.v4.iss5.p1

Published Date: 18-Oct, 2025

Keywords: VNTR profiling; forensic DNA analysis; biological evidence (blood, saliva, hair); DNA quality & inhibitors; reproducibility.

Abstract:
The research paper examines the pharmacognostic assessment, as well as the in-vivo studies. This paper presents a rigorous, expert-level comparative evaluation of Variable Number Tandem Repeat (VNTR) profiling applied to three common forensic biological matrices blood, saliva, and hair in a hypothetical project designed to illuminate foundational issues in forensic DNA analysis. Although VNTRs have been largely superseded by Short Tandem Repeat (STR) systems in contemporary casework, VNTR-based workflows remain a powerful pedagogic vehicle for exploring the core determinants of analytical performance. Using standardized extraction and VNTR-typing workflows across matrices, we systematically examined analytical efficiency, genotype quality, and reproducibility while assessing the impact of starting DNA quantity, matrix-specific inhibitory substances, and sample-associated contamination. Comparative findings indicate that whole blood consistently yielded the highest-quality and most reproducible VNTR profiles, whereas saliva produced variable results influenced by bacterial and food-derived contaminants, and hair particularly shed or rootless shafts frequently returned low-yield or partial profiles. Reproducibility analyses highlighted greater intra- and inter-assay variability for saliva and hair compared with blood, underscoring matrix-dependent limits on discriminatory power. Beyond historical interest, these results translate directly to modern STR practice: they clarify why sample collection, inhibitor mitigation, and DNA quantitation remain critical determinants of success irrespective of marker system. The study therefore both situates VNTRs in the historical arc of forensic genetics and distills enduring methodological lessons for contemporary forensic laboratories and training programs.

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