Mother-child double incompatibility at vWA and D5S818 loci in paternity testing

Abstract

In a paternity dispute case, 17 autosomal short tandem repeats (STR) were examined and signified a possible paternal mismatch at vWA locus and a maternal mismatch at D5S818 locus in the child under investigation. Seventeen autosomal, 17 Y-chromosome and six X-chromosome repeat loci were used in parentage analysis. The mutated vWA and D5S818 alleles were amplified, cloned and sequenced to analyze the repeat structure. The vWA locus genotype in the mother, questioned child and suspected father were 18/19, 16/18 and 14/18, and were 13/15, 11/12 and 11/14, respectively, for the D5S818 locus. A complete match with the mother at six X-chromosome STR loci and with the father at 17 Y-chromosome STR loci was observed. Nucleotide sequence analysis of the family at vWA alleles indicated the maternal loss of the repeat motif TCTA by two repeat units and a loss of AGAT repeat by one unit in the D5S818 locus leading to an allele mismatch in the child. The probability of maternity and paternity were 0.999999 and 0.999999, respectively. This is the first study of a maternally transmitted microsatellite mutation in the loci D5S818 and vWA in paternity DNA testing. The results convincingly established that the mother and suspected father are the biological parents of the questioned child.