Effect of DNA Profile Size, Reference Population Database, and Parents Availability on Parentage Testing in Consanguineous and Endogamous Populations: The Lebanese Case

Abstract

Short tandem repeats (STR) analysis is currently the gold-standard method for DNA profiling in parentage testing where the probabilistic analysis is affected by the DNA profile size, the STR frequency dataset, and the availability of all the individuals involved in the case. Lebanon is a relative small country with high rates of endogamous and consanguineous marriages; factors that could challenge the power of discrimination of the DNA profiles and introduce uncertainty to parentage testing interpretations. Since there is no legislation concerning kinship testing in Lebanon, relationship testing laboratories follow standards of their own choice, the majority of parentage testing is performed using 15 STR systems only, and some laboratories still use Caucasian STR allele frequencies as reference population datasets. In addition, there is a remarkable increase in Duo parentage testing requests. The present study aimed at assessing the effect of the number of tested STR loci 15 versus 23, and the effect of using Lebanese versus Caucasian STR allele frequencies as reference population dataset in 422 Trio and 271 Duo parentage cases. Results showed that performing paternity testing using DNA profiles of 15 STR systems in the Lebanese population increased the risk of misinterpretations, whereas increasing the DNA profile size to 23 STR markers using the population representative STR allele frequency helped remarkably in lowering uncertainties, and probable misinterpretations, especially in Duo parentage cases.