Primer binding site mutations affecting the typing of STR loci contained within the AMPFlSTR SGM Plus kit

The Forensic Science Service carries out human identification and familial investigations using the AMPFlSTR SGM Plus kit (PE Biosystems, Warrington, England). We have studied approximately 42,000 parent/child allelic transfers (meioses) for deviations from expected Mendelian Inheritance patterns. Of 55 apparent mutations detected, 20 had patterns suggestive of the presence of a primer binding site mutation producing a silent/null allele. The presence of a silent allele was unequivocally demonstrated in 13 of the 20 suspected cases by using alternative primer sets. Of the 13 confirmed cases, 9 involved the D18S51 locus. As the individuals in these cases all originated from the same geographic region of the Middle East, this cluster suggests the presence of a relatively common variant D18S51 allele in that particular group. These data taken together with our previously published work, confirm that the primer binding sites utilised for amplification of the loci contained in the AMPFlSTR SGM Plus kit have highly conserved nucleotide sequences.