Hypervariable locus of the 3′-flanking region of the neurotensin receptor gene: an effective region for personal identification in forensic practice

• Published in: Forensic science international 2002-06, Vol.127 (1-2), p.119-127
• Main Authors: Tomita, Masafumi, Nohno, Tsutomu, Okuyama, Toshiko, Hidaka, Kazuo, Xu, Weiming
• Format: Article
• Language: English
• Subjects: Alleles; Biological and medical sciences; Classical genetics, quantitative genetics, hybrids; Deoxyribonucleic acid; Direct sequencing; DNA; Electrophoresis; Fluorescence; Fluorescent-labelled PCR; Forensic Medicine; Forensic science; Forensic sciences; Fundamental and applied biological sciences. Psychology; Gene deletion; Gene frequency; Gene polymorphism; Genetics of eukaryotes. Biological and molecular evolution; Genome, Human; Genotype; Human; Humans; Insertion; Japan; Loci; Minisatellite Repeats - genetics; Neurotensin; Neurotensin receptor gene; Nucleotides; Personal identification; Phenols; Polymerase Chain Reaction; Polymorphism; Receptors, Neurotensin - genetics; Structural polymorphism; Variation
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/S0379-0738(02)00091-9

We examined the complex short tandem repeat (STR) locus at the 3′-flanking region of the neurotensin receptor (NTR) gene. The polymorphism of this locus was first reported as a simple tetranucleotide repeat variation by Le et al. [1], but it also offers a surprisingly informative variation, that permits reliable individual identification by two complementary strategies: fluorescent-labelled polymerase chain reaction (PCR)/electrophoresis and direct sequencing of the PCR products. We determined the alleles in 203 Japanese by fluorescent-labelled PCR/electrophoresis. Determination was based on their length with a reliability of ±1bp, and the frequency of each allele was very low. Sequencing analysis further grouped these alleles in detail. Sequencing demonstrated that the locus varied by six repetitive units and three insertion/deletion positions of nucleotide fragments. We detected multiple alleles having different structures even in the same allele length. We found structural differences in homozygous alleles having the same base pair size. We also determined that apparently homozygous alleles were heterozygous from sequencing electropherograms showing an overlap of nucleotides or ±1bp difference. These results indicate that this locus is structurally hypervariable in addition to having allelic length variations, promising a great advance in individual identification in forensic practice.