Estimates of mutation rates from incompatibilities are misleading - guidelines for publication and retrieval of mutation data urgently needed

Abstract

Unbiased estimation of germinal mutation rates are essential for population and evolutionary genetic analyses and in any forensic kinship evaluation. A major source of bias in diploid or haplodiploid loci was identified – ‘hidden’ or ‘covert’ mutations (i.e. those not causing Mendelian incompatibilities) and ways to overcome it proposed. Morever, the identification of (a) the parental meiosis in which mutation has occurred, as well as (b) the allele of origin and the mutated one, are problematic. A pseudo most parsimonious approach goes on being used although it was already shown that misclassification of mutations has a significant impact, overestimating one-step mutations and underestimating all others.In forensics, current publication and other publicly obtainable data formats ignore both types of bias and do not allow more than the estimation of average incompatibility rates per locus. These values are biased and, in kinship analyses, estimates of biallelic specific mutation rates considering also its parental origin, should be used for correct likelihood calculations.We urge the forensic community to undertake the task of preparing guidelines for archival, retrieval and most specially, publication of data in a format that will allow a more accurate estimation of this crucial parameter, providing a solid ground for the formulation and testing of mutation models. For this, the publication of the complete set of observed genotypes in duos and/or trios in the population sample is mandatory.