Unexpected patterns in Y-STR analyses and implications for profile identification

Y-STR analysis is widely used in many fields, such as paternity testing, genealogy studies and in male/female mixtures. In many rape cases, Y-STRs are also useful for the determination of contributors’ number. Here we described a father/son pair with double peaks at DYS439 and DYS635 loci. This case should focus the attention on forensic interpretation of Y-haplotype profiles, because multiple alleles at various loci do not forcibly indicate that the sample originates from a mixture.We also report a case of two half-brothers with null allele at DYS448.Since DYS439 and DYS635 loci are located in the AZFa region and DYS448 locus in the AZFc region, we performed a molecular genetics study of these regions to evaluate a possible correlation between Y-STR profiles and Y chromosome deletions involved in infertility.