Complex casework using single nucleotide polymorphisms

Abstract

Complex kinship analyses are normally a challenge for forensic laboratories, especially in cases in which the individuals involved can have criminal responsibilities. This paper presents two complex relationship caseworks studied with routine STRs and autosomal SNPs as supplementary markers. In the first case, to exclude trafficking of children, maternity investigation of a child was requested involving two alleged mothers – a 39-year-old woman, the alleged grandmother, and her absent daughter. The second one was a possible incest case with a young girl with Trisomy 21 where her father was also the alleged child's father. The individuals of these cases were typed for 17 autosomal STRs with AmpF lSTR Identifiler or IdentifilerPlus and Powerplex 16. Twenty autosomal SNPs were also typed using SNaPshot ® methodology, with two 10-plex previously revealed useful in paternity testing. Both cases gave low likelihood ratio values with STRs and a genetic incompatibility was also detected in the first case. SNP studies strongly indicated that the alleged grandmother was not the child's mother but indeed the grandmother in a real complex immigrant kinship case, while in the second casework reinforced the incest relationship. Therefore, SNPs revealed useful as additional markers in complex kinship testing.