Effect of Motherless Paternity Cases on the Interpretation of Parent age Investigations in a Population with Recurrent Inbreeding Practices

Abstract

Currently, parentage testing relies mainly on the study of Short Tandem Repeats (STRs) DNA profiles. Parentage cases could be DUO (motherless/fatherless cases) or TRIO (where both parents' and child's DNA profiles are available). The absence of the DNA profile of one of the parents in DUO parentage testing increases the testing uncertainties. The Lebanese population is known to have a high rate of endogamous and consanguineous marriages, which challenges the power of discrimination of the DNA profiles among different individuals. The present study aimed at evaluating the effect of motherless paternity cases on the interpretation of parentage investigations in the Lebanese population with recurrent inbreeding practices. 64 real DUO parentage exclusions and 15 real TRIO parentage exclusion cases were re-evaluated by assessing the possibility of false inclusions when decreasing DNA profile sizes or when simulating DUO cases from TRIO ones. One case showed false positivity with 6 mismatches in its TRIO state, but only one mismatch in its DUO scenario. The probability of parentage (POP) obtained for this case after omitting the mismatch (a frequent inappropriate malpractice in some local laboratories) was 99.9%. This simulated DUO case was cleared as an exclusion when tested using DNA profile sizes of 24 STR markers. None of the other cases showed false positive results.