Dxs10134 Dxs7423

Figure 7.1 Chromosome X ideogram with STR markers handling and some are routinely used by our own group and others. Solely DXS10011 should be singled out. This tetranucleotide repeat marker occurs in two sequence variants, type A and B. Whereas the type B allele mutation rate is comparable with other STRs, type A alleles mutate with very high frequencies (Hering et al., 2004). In general, mutation rates of ChrX STRs seem not to differ from microsatellites of other chromosomes. An early report on a high rate of mutation in DXS981 (Mahtani and Willard, 1993) could not be confirmed in kinship testing and seems to be a misinterpretation of results obtained when working with lymphoblastoid cell lines of CEPH families (Banchs et al., 1994).

Typical STRs show regular structure with constant length differences between different alleles, i.e. 3, 4 or 5 bp steps. However, several markers such as DXS7130 and DXS6803 (Edelmann and Szibor, 2003), DXS10011 (Watanabe et al., 2000; Hering et al., 2004) and DXS981 (Mahtani and Willard, 1993; Tabbada et al., 2005) are composed of different repeat units resulting in 2 or

Table 7.2 Characteristics of ChrX STRs in forensic use based on allele distribution in a European population

Physical and genetic

Table 7.2 Characteristics of ChrX STRs in forensic use based on allele distribution in a European population

Physical and genetic

Was this article helpful?

0 0

Post a comment