After noting that when a forensic DNA sample cannot be associated directly with a previously genotyped reference sample by standard short tandem repeat profiling, the investigation required for identifying perpetrators, victims, or missing persons can be both costly and time consuming, this article describes the outcome of a collaborative study that used the Identitas Version 1 (v1) Forensic Chip, the first commercially available all-in-one tool dedicated to the concept of developing intelligence leads based on DNA.
The chip enables parallel interrogation of 201,173 genome-wide autosomal, X-chromosomal, Y-chromosomal, and mitochondrial single nucleotide polymorphisms for inference of biogeographic ancestry, appearance, relatedness, and sex. The first assessment of the chip’s performance was conducted on 3,196 blinded DNA samples of varying quantities and qualities, covering a wide range of biogeographic origin and eye/hair coloration, as well as variation in relatedness and sex. Overall, 95 percent of the samples (N = 3,034) passed quality checks with an overall genotype call rate >90 percent on variable numbers of available recorded trait information. Predictions of sex, direct match, and first-degree to third-degree relatedness were highly accurate. Chip-based predictions of biparental continental ancestry were on average ~94 percent correct (further support provided by separately inferred patrilineal and matrilineal ancestry). Predictions of eye color were 85-percent correct for brown and 70-percent correct for blue eyes, and predictions of hair color were 72 percent for brown, 63 percent for blond, 58 percent for black, and 48 percent for red hair. From the 5 percent of samples (N = 162) with <90 percent call rate, 56 percent yielded correct continental ancestry predictions, and 7 percent yielded sufficient genotypes to enable hair and eye color prediction. The results demonstrate that the Identitas v1 Forensic Chip holds great promise for a wide range of applications, including criminal investigations, missing person investigations, and for national security purposes. (publisher abstract modified)