Forensic insights into genetic polymorphism and tri-allelic pattern in the Brahmin population of Gujarat, India, using 21 autosomal STR markers.

Abstract

India's genomic diversity is influenced by regional population dynamics and strong endogamy. The present study explores the genetic structure of the Brahmin population in Gujarat, a culturally and genetically preserved community, using autosomal Short Tandem Repeats (STR). Genomic DNA from the blood samples of 819 healthy individuals (562 males and 257 females) were subjected to autosomal STR typing using the GlobalFiler™ Express PCR Amplification Kit. Capillary electrophoresis-based fragment analysis was performed using the ABI 3500 Genetic Analyser, and proceeded to genotype analysis using GeneMapper ID-X. In total, 74 alleles were assessed with observed heterozygosity (Ho) of 0.80 ± 0.01, expected heterozygosity (He) of 0.79 ± 0.02, and unbiased expected heterozygosity (uHe) of 0.79 ± 0.02. Hardy-Weinberg equilibrium was followed by most of the markers except D16S539 and D3S1358. Forensic efficiency measures (PIC = 0.63-0.95; PD = 1; PE = 0.99999) confirmed the significance of these markers for genetic and forensic research. Additionally, comparative genomic analysis using principal component analysis (PCA) and multidimensional scaling (MDS) revealed close genetic affinity between Brahmins of Gujarat and Brahmins from Haryana and Rajasthan. These findings enhance the genetic makeup of the Brahmin population of Gujarat. Additionally, a novel germline-origin Type 2 tri-allelic pattern (8, 9, 11) at the D13S317 locus was identified in a healthy male participant, which was traced to a Type 2(B) tri-allelic variant at the same locus in his biological mother. These findings highlight the need for understanding the tri-allelic pattern for its appropriate interpretation in STR analysis.