As well known, the mutations of the STR loci revealed in resolving the identification, disputed paternity/mothernity, kinship, etc. cases reduce to some extent the reliability of the results and deliver a certain difficulty in preparation of an accurate expert opinion. Therefore, information on the facts of detection of such allelic variations has great practical importance. In this study among 250 family cases of disputed paternity we found mutated alleles in two cases on FGA, in two cases on D19S433, in one case on D13S317 and in one case on D5S818 locus. In five cases more likely these mutations affected the paternal alleles, in one case the maternal allele. For each case possible mutation formation ways scheme was proposed. Moreover, in one case three-allelic profile on D21S11 locus has been observed indicating three copies of chromosome 21, which supported existing Down’s syndrome phenotype.