Genetic analysis of father-daughter incest using multifaceted STR markers and study of inheritance pattern of alleles

Background: Two cases involving father-daughter incest, a rare report in the Indian population, have been analyzed in the current study. STR markers on both autosomal and sex chromosomes were employed to expound the cases. Objective: To confirm the identity of the fetus as a product of father-daughter incest and to study the inheritance pattern of alleles in such cases. Results: In both cases, the aborted fetus was found to be the product of an incestuous father-daughter relationship. The probability of paternity as well as maternity was found to be >99.9999% in both cases. Analysis of other paternity and forensic parameters also substantiated the inclusion of the alleged individuals. Father-daughter incest had a tremendous effect on the genome as evidenced from the dramatical decrease in unrelated alleles between father/child [16.66% (Case 1), 20% (Case 2)] and mother/child [26.66% (Case 1), 21.66% (Case 2)]. Genetic evidence also suggested an increased biallelic match i.e., 26.66% (Case 1) and 33.33% (Case 2) between mother and fetus which are at par/ above the normal siblings’ values i.e., 26.66%. Conclusion: A significant increase in the percentage of homozygous alleles (53.33% in both cases) was observed in the product of father-daughter incest. Both daughters share the same X chromosome from the father, which also suggested the case to be of father-daughter incest. Similarly, the same Y-STR profile between the male fetus and alleged father confirmed the correct pattern of inherit1ance of the Y chromosome in this case.