A rare case of type II tri-allelic inheritance at vWA, SE33, D8S1179, and D13S317 loci demonstrated by STR analysis in paternity testing.

Short tandem repeat (STR) typing has been regularly used in paternity disputes and forensic human identification linked caseworks. Occasionally, forensic scientists come across aberrant allele patterns during STR typing because of mutations, genetic variations, and other abnormalities. The tri-allelic pattern of STR is rare, particularly, the case where this pattern exists at 4 loci.