Allele frequencies of nine STR systems in the Flemish population and application in parentage testing

Abstract

In order to apply a set of nine STR loci in parentage testing, we performed a population genetic study on a sample of the Flemish population. Genotypes for HUMHPRTB, HUMFABP, HUMCD4, HUMCSF1PO, HUMTH01, HUMPLA2A, HUMPLA2A1, HUMF13A01, HUMCYAR04 and HUMLIPOL were determined using three triplex PCR reactions and silver staining. Allele frequencies showed no deviation from Hardy-Weinberg equilibrium. The frequency distribution agreed well with other Caucasian populations but three intermediate fragments, not previously found in Caucasians, were observed. We then resolved a series of 151 parentage disputes of which 103 were exclusions. In six cases, evidence for exclusion was obtained by only one informative STR locus out of eight for male children or out of nine for female children. These exclusions were confirmed with additional polymorphic markers. In one case of inclusion, a paternal allele expanded with one repeat unit of HUMHPRTB. This observation illustrates that STRs do not differ from other genetic systems in the fact that more than one excluding locus is required before exclusion is demonstrated.