A Single Step Mutation at D3S1358 Locus in a DNA Paternity Testing with 2 Alleged Fathers.

Background: Genetic information is used very frequently in human identification in civil or judicial cases. Establishing the kinship relationship between a child and his biological father involves many ethical facts. We describe a DNA paternity case with two alleged fathers and an inconsistency between alleged father-2 and the child at D3S1358 locus.

Methods: As biological samples we used saliva collected from inside the cheek of each person using buccal swabs (Copan, Italy). We collected the biological samples from each of person after each person gave the consent. In order to find the concentration of salivary DNA, the DNA samples were quantified by 7500 ABI Real-time PCR using the Quantifiler Human DNA kit (Applied Biosystems, USA). The next step was the amplification of the Salivary DNA samples by polymerase chain reaction (PCR). It was performed on a ProFlex PCR System (Applied Biosystems, USA) using the multiplex STR markers from the AmpFlSTR® Identifiler Plus Amplification Kit (Applied Biosystems, USA). After amplification, the PCR products were run on capillary electrophoresis on an ABI 3500 Genetic Analyzer (Applied Biosystems, USA).

Results: AF-1 was excluded as biological father. The DNA profiles of AF-2 and the child had one mismatch at D3S1358 locus. Further, we amplified the Y-STR markers to confirm the mutation, obtaining a perfect match between the 2 persons.

Conclusions: In paternity testing, where one or two inconsistencies are present between the child and the alleged father on autosomal STR markers, the use of haploid markers X-STR or Y-STRs is needed for the confirmation or exclusion of paternity.