Six of them demonstrated haplogroup I, five had haplogroup R1a and one showed haplogroup R1b. Therefore, we deduce that the 12 persons with this double null allele do not originate Selleckchem RAD001 from one male lineage, and that this double null allele is recurrent and identical by state among the different haplogroups. When examining the Y-STR haplotypes for the persons belonging to the same haplogroup (I or R1a), it was noticed that two donors in haplogroup I showed haplotypes with only one difference between them, while all others

displayed at least five differences (data not shown). This one difference was detected in the rapidly mutating DYF403S1b marker and we infer that these two donors may be (closely) related in the male lineage, which would mean that, in this case, the double null allele is identical by descent. However, relationship testing based on 23 autosomal STRs did not suggest a first or second degree relationship ABT-199 molecular weight between these donors (data not shown). A noteworthy observation occurred for single copy marker DYS576, as in one person an additional allele 14 of low peak height was found next to a much higher allele 18 in both PPY23 and RMY2 profiles. The peak height ratio between both alleles varied between 0.12

and 0.31 in four independent amplifications with both multiplexes. The presence of the two alleles was confirmed with Sanger sequencing, although the signals for allele 14 were again very low and did not allow detecting Interleukin-3 receptor a possible primer binding site mutation. As the PCR primers for Sanger sequencing were positioned at least 100 nucleotides further up- and downstream than those used in RMY2 (and the primer positions for PPY23 are unknown), we infer either the presence of multiple primer binding site mutations, or a chimeric situation that is specific for this Y-STR marker as none of the other Y-STR or autosomal markers showed

additional weak alleles. More detailed sequence information may be obtained from next generation sequencing [10], but for now it remains unclear what causes the presence of the second lower allele on DYS576 in this sample. Four RM Y-STR marker units (DYF387S1, DYF399S1, DYF403S1a and DYF404S1) most often show multiple alleles per marker (between one and five alleles, Table 1), and are therefore categorised as multi copy markers. The other 32 marker units are considered single copy markers, although 14 of these, including the previously described DYS576, show a second allele in one to six of the 2085 samples (Table 1). In 26 of the 32 cases, the second allele differs only one repeat length in size from the first allele, but size differences up to six repeat lengths have been found. Except for the previously described sample showing two unbalanced alleles in DYS576, both alleles are balanced in the other cases.