Rapid and accurate biological sex estimation by LAP-MALDI MS analysis of child teeth

We recently introduced a new rapid workflow for biological sex estimation of human skeletal remains from archaeological sites based on LAP-MALDI MS and MS/MS analysis of amelogenin peptides extracted from tooth enamel. With this workflow, a simple classification rule for biological sex estimation was established using panels of MS and MS/MS ion signals. Importantly, the employed LAP-MALDI analysis required only a single 1 μL sample droplet and no further peptide separation. Here, we present the application of this rapid workflow and associated classification rule to a set of nine teeth from individuals of unknown biological sex dating to the medieval period (900-1540 CE), including teeth from four children, which were also assessed by conventional osteology. For the five teeth from adult skeletons, the recorded LAP-MALDI MS and MS/MS ion signal panels led to a 100% agreement in the assignment of the biological sex between osteology and LAP-MALDI. Such ion signal panels also provided biological sex estimation for the four child teeth, including three deciduous teeth. Two of these estimates agreed with the osteological assessment. The other two were not in agreement with the osteological assessment. In one case, predominately female osteological characteristics were obtained, while LAP-MALDI analysis clearly identified the individual as male owing to the unambiguous detection of the Y-chromosomal amelogenin peptide SM_oxIRPPY. In the other case, male osteological characteristics were found, but the osteological assessment was more ambiguous and LAP-MALDI analysis could not detect any MS or MS/MS ion signals of SM_oxIRPPY that would have substantiated a male assignment.