Investigator HDplex markers: allele frequencies and mutational events in a North Italian population

Abstract

Autosomal short tandem repeats (STRs) analysis represents the method of election in forensic genetics and up to now, 23 STRs are available for these purposes. However, in particular circumstances such as human identification or complex kinship cases, examination of additional STRs may be required in order to obtain reliable conclusions. For this purpose, a new multiplex STR system, namely Investigator® HDplex kit (QIAGEN) that coamplifies a set of 12 autosomal loci, 9 of which, represents novel supplementary STRs, was recently developed. A population sample of 359 unrelated healthy subjects residing in North Italy was typed to determine allele frequencies, forensic parameters and genetic distances among European populations. Furthermore, to evaluate the suitability of the HDplex kit as an auxiliary tool for paternity testing, mutation rates were estimated on 84 confirmed family trios. The 12 loci resulted highly informative with a combined power of discrimination of 0.999998 and no departures from Hardy-Weinberg equilibrium were observed with the sole exception of locus D4S2366. From the comparison of our population sample and European reference populations, a single significant difference was revealed with the Poland population at D4S2366 locus. With regard to the mutation rate study, on a total of 2,016 meioses considered, six single-step mutational events were observed and the average mutation rate calculated was of 2.94 × 10(-3) per locus per generation (95% confidence interval, 1.08 × 10(-3)-6.39 × 10(-3)).

Evaluation of forensic genetic parameters of 12 STR loci in the Korean population using the InvestigatorⓇ HDplex kit

“…Comparison of our allele frequencies with those previously reported across different populations revealed statistically significant differences in p values between Korean and Argentinean populations [2] across all 12 STR loci, North Italian [4] at 10 STR loci, Dutch [6] at 11 STR loci, and Shanghai [8] at 2 STR loci, but similarity with Japan at all 12 STR loci (Table S2). In particular, the Korean population was significantly different from all populations, except Japanese, at D6S474 and D12S391.…”

“…These 20 loci are considered to provide sufficient genetic information for forensic analyses [1][2][3]. However, additional STR loci may be required to supplement and support scientific conclusions and increase the reliability of the genetic results, particularly in more difficult cases like kinship analyses [2,4].…”

“…Forensic genetic studies using the Investigator Ⓡ HDplex kit have been performed in different laboratories [2,[4][5][6][7][8]. To date, the use of the Investigator Ⓡ HDplex kit to calculate the forensic genetic parameters of the Korean population has not been reported.…”

“…Calculations of allele frequencies, observed and expected heterozygosity, the values of Fst, and pairwise p values for the pairwise comparison of genetic distances in Korean and other populations were performed using Arlequin v3.5. Allele frequencies were obtained from published population data including Argentinian [2], North Italian [4], Dutch [6], Japanese [7], and Shanghai Han [8] populations. The population genetics parameters including matching probability (PM), power of discrimination (PD), polymorphism information content (PIC), and power of exclusion (PE) were calculated using PowerStats v1.…”

Polymorphism of 12 STR loci included in the Investigator HD-plex kit in Polish population of Lodz region

“…Łączna siła wykluczenia dla zestawu badanych markerów (PE) wyniosła 0,999999879, a średni indeks ojcostwa dla pojedynczego markera 4,26. Uzyskane wysokie wartości parametrów biostatystycznych dla populacji Polski centralnej są zbliżone do analogicznych parametrów uzyskanych dla innych populacji [15][16][17][18][19][20]. Świadczy to o bardzo wysokiej przydatności badanego zestawu Investigator HD-plex do badań zarówno z zakresu identyfikacji osób, jak i analizy ojcostwa.…”