Detection of Deletion/Insertion Polymorphism Profiles from Single Human Hair Shafts

Background: Hair is a frequently encountered biological evidence in personal identification. The amount of nuclear DNA that can be extracted from a single strand of rootless hair is most limited, making the detection of short tandem repeat (STR) polymorphisms difficult. To overcome these limitations, deletion/insertion polymorphisms (DIP) as a new type of genetic marker have shown their benefits in detecting low-copy-number DNA. The Investigator DIPplex kit contains 30 biallelic autosomal DIP and amelogenin. The analysis of DIPs combines the advantages of both STR and single nucleotide polymorphism analyses. Thus, this study aimed to detect the DIP distribution of individual hair shafts from individuals.Methods and Results: DNA was extracted from the shaft of fresh, aged, and shed hair. After DNA was evaluated, the DIP profiles were detected by capillary electrophoresis. The results indicated that the amount of DNA extracted from hair roots was much higher than that from the hair shafts in the same individual for all samples. The degradation index values of DNA from the aged hair shafts were highest. It is classified to be “mildly degraded.” Compared with their hair roots, the full DIP profiles were detected for fresh hair, 70% for aged hair, and 92% for shed hair. Contrarily, except for fresh hair shafts, only three STR loci of the aged and shed strands of hair could be amplified using AmpFlSTR MiniFiler PCR Amplification Kit.Conclusions: These results indicate that the detection of DIP profile is an effective tool for personal identification from hair shafts, including aged hair.

Population genetics of 30 insertion/deletion polymorphisms in the Bahraini population

This paper evaluates the forensic utility of 30 insertion-deletion polymorphism (indel) markers in a sample from the Bahraini population using the Qiagen Investigator DIPplex Kit. Allele frequencies and forensic stats of the 30 indels were investigated in 293 unrelated individuals from different governorates of the Kingdom of Bahrain. None of the markers showed significant deviation from Hardy Weinberg equilibrium except for HLD88 locus and no linkage disequilibrium were detected between all possible pair of the indel loci, assuming that these markers are independent and their allele frequencies can be used to calculate the match probabilities in the Bahraini population. The high power of discrimination (CPD = 0.9999999999998110) and the low combined match probability (CPM = 1.89 × 10−13) indicate that these markers are informative and can be successfully used for human identification in terms of forensics and paternity. Genetic distances and relatedness were displayed through multidimensional plotting and phylogenetic tree using various populations in the region. Our study showed that the Bahraini population was clustered with neighboring countries such as Kuwait and Emirates which indicates that these closely geographical regions share similar allele frequencies and are more genetically related than other reference population studied.