Multistep microsatellite mutation in the maternally transmitted locus D13S317: a case of maternal allele mismatch in the child.

Examination of a case of a paternity dispute with 17 autosomal short tandem repeats (STR) loci revealed a mismatch of the maternally transmitted allele at the locus D13S317 in the questioned child. The composition of the alleles of this locus in the mother, questioned child and suspected father was 8/8, 11/11 and 8/11, respectively. The sequence analysis of the regions flanking the locus D13S317 and peak height measurements of the paternal, maternal and child alleles at this locus excluded the possibility of null allele as a cause of the allelic mismatch inherited by the child.