Forensic parameters and genetic structure analysis of 30 autosomal InDels of the population in Freetown, Sierra Leone.

As the origin of modern humanity, African populations show high genetic diversity and are attracting increasing academic attention. However, populations living in West Africa have so far received less study and exploration. In this study, we analyze 30 insertion/deletion (InDel) loci of 516 samples from Freetown, Sierra Leone, to evaluate the forensic properties and reveal the genetic structure in Freetown, Sierra Leone, West Africa. No significant linkage disequilibrium (LD) between 30 InDels was observed after the Bonferroni correction. The random match probability (RMP), the combined power of exclusion for duos (CPE duos), and the combined power of exclusion for trios (CPE trios) were 6.823 × 10-11, 0.9168, and 0.9731, respectively. Null alleles and off-ladder alleles were observed, suggesting that we should be cautious when using this kit for forensic caseworks in African populations. In the population comparison study, we found that the Freetown population is genetically closer to geographically distinct West Africans and has a closer genetic relationship with the Bantu-speaking populations than other African populations.

Genetic characterization of 19 X-STRs in Sierra Leone population from Freetown.

A total of 550 individuals (265 males and 285 females) from Sierra Leone, a west-African coastal country, were genotyped using the Microreader™ 19X ID System kit. No significant deviations from the Hardy-Weinberg equilibrium were observed. A total of 250 alleles were identified with corresponding allele frequencies spanning from 0.0012 to 0.6762. PIC of the loci ranged from 0.4615 to 0.9481. The CPE, CPDF, and CPDM were 0.9999997856, 0.999999999999999999995774, and 0.999999999998997, respectively. The highly combined MECKruger, MECKishida, MECDesmarais, and MECDesmarais Duo were achieved as 0.99999992508, 0.999999999990802, 0.999999999990836, and 0.99999998412, respectively. Genetic comparisons revealed that genetic homogeneity existed in similar ethno origin or geographic origin populations. This is a pioneering genetic investigation using the Microreader™ 19X ID System kit in the population of Sierra Leone.