Inherited alleles revealing an incestuous paternity

Some rape cases result in the pregnancy of the victim and if the case is not reported to the police after the act with a subsequent gynaecological examination of the girl and the taking of a vaginal swab, there is no way of connecting the rape case with the perpetrator, except by parentage determination using DNA (deoxyribonucleic acid) analysis after abortion or induced delivery. In order to solve the rape case of a minor girl of 14 years which resulted with pregnancy, where a 60-year-old man was accused of the rape, DNA was extracted from blood samples from the girl and the putative assailant and from the foetus after its induced delivery. The autosomal short tandem repeats (STR) typing for 15 different loci showed differences in 6 STR loci between the putative assailant as a father and the foetus, thus excluding the tested paternity. A large number of identical loci between the mother's and the child's genotype led us to consider the possibility of incestuous paternity. Analysis of DNA samples from the girl's father and brother clarified the case as brother-sister incest.