Sibling incest and formulation of paternity probability: case report

Area of Science:

• Forensic Genetics
• Human Genetics
• Molecular Biology

Background:

• Paternity determination is crucial in legal and social contexts.
• Complex familial relationships can pose challenges in genetic testing.
• The case involved a fetus from a mother residing in a welfare institution.

Purpose of the Study:

• To determine the paternity of a fetus in a complex familial situation.
• To apply advanced DNA profiling techniques for accurate kinship analysis.
• To develop and validate new methods for paternity probability calculation in incest cases.

Main Methods:

• DNA samples were collected from the fetus, mother, her brother, father, grandfather, and institutional staff.
• Short Tandem Repeat (STR) analysis using commercially available kits (MCT118, HLADQA, PM, 9 STRs).
• Multilocus and single locus minisatellite DNA fingerprinting for confirmation.
• Development of new statistical formulations for paternity probability in sibling incest.

Main Results:

• The mother's younger brother was the only individual not excluded as the father.
• Paternity probability was estimated at 99.857% assuming sibling incest.
• DNA fingerprinting corroborated the paternity findings.
• Bandsharing frequencies did not accurately reflect kinship in this consanguineous case, highlighting limitations.

Conclusions:

• The fetus was fathered by the mother's brother.
• Multilocus DNA fingerprinting requires more data for reliable analysis in incest cases.
• A universal formulation for calculating paternity probability in sibling incest using multiallelic polymorphisms was presented.